MDPI - Publisher of Open Access Journals

24 pages, 2511 KiB

Open AccessArticle

Phytoplankton Assemblage over a 14-Year Period in the Adriatic Sea: Patterns and Trends

by Sanda Skejić, Blanka Milić Roje, Frano Matić, Jasna Arapov, Janja Francé, Mia Bužančić, Ana Bakrač, Maja Straka and Živana Ninčević Gladan

Biology 2024, 13(7), 493; https://doi.org/10.3390/biology13070493 (registering DOI) - 2 Jul 2024

Abstract

Considering the role of phytoplankton in the functioning and health of marine systems, it is important to characterize its responses to a changing environment. The central Adriatic Sea, as a generally oligotrophic area, is a suitable environment to distinguish between regular fluctuations in [...] Read more.

Considering the role of phytoplankton in the functioning and health of marine systems, it is important to characterize its responses to a changing environment. The central Adriatic Sea, as a generally oligotrophic area, is a suitable environment to distinguish between regular fluctuations in phytoplankton and those caused by anthropogenic or climatic influences. This study provides a long-term perspective of phytoplankton assemblage in the central eastern Adriatic Sea, with 14 years of continuous time series data collected at two coastal and two offshore stations. The predominant phytoplankton groups were diatoms and phytoflagellates, but their proportion varied depending on the vicinity of the coast, as evidenced also by the distribution of chlorophyll a. In the coastal environment, the phytoplankton biomass was substantially higher, with a higher proportion of microphytoplankton, while small phytoplankton accounted for the majority of biomass in the offshore area. In addition, a decreasing trend in diatom abundance was observed in the coastal waters, while such trend was not so evident in the offshore area. Using a neural gas algorithm, five clusters were defined based on the contribution of the major groups. The observed increase in diversity, especially in dinoflagellates, which outnumber diatom taxa, could be a possible adaptation of dinoflagellates to the increased natural solar radiation in summer and the increased sea surface temperature. Full article

(This article belongs to the Special Issue Climate Change and Marine Plankton)

9 pages, 384 KiB

Open AccessArticle

Clinical Effectiveness of Targeted Therapies Following Nivolumab Therapy in Patients with Metastatic Renal Cell Carcinoma: A Real-World Study

by Deniz Işık, Oğuzcan Kınıkoğlu, Goncagül Akdağ, Yunus Emre Altıntaş, Ezgi Türkoğlu, Sedat Yildirim, Heves Sürmeli, Tuğba Başoğlu, Hatice Odabaş and Nedim Turan

Medicina 2024, 60(7), 1088; https://doi.org/10.3390/medicina60071088 - 2 Jul 2024

Abstract

Background: The treatment and escape for metastatic renal cell carcinoma (RCC) has rapidly evolved, particularly with the integration of immune therapies into first-line regimens. However, optimal strategies following progression in first-line immunotherapy remain uncertain. This study aims to evaluate the efficacy and safety [...] Read more.

Background: The treatment and escape for metastatic renal cell carcinoma (RCC) has rapidly evolved, particularly with the integration of immune therapies into first-line regimens. However, optimal strategies following progression in first-line immunotherapy remain uncertain. This study aims to evaluate the efficacy and safety of axitinib and cabozantinib as third-line therapies after progression on nivolumab following first-line VEGF-TKI therapy. Methods: Patients with metastatic RCC who progressed on prior nivolumab treatment after receiving first-line VEGF-TKI therapy were included. Data on patient characteristics, treatment regimens, response rates, progression-free survival (PFS), and overall survival (OS) were collected. Statistical analyses were conducted to assess the prognostic factors and treatment outcomes. Results: A total of 46 patients were included who were predominantly male (83%) with clear-cell histology (89%). The median PFS on first-line TKI therapy was 10.2 months. All the patients received nivolumab as a second-line therapy, with a median of 12 cycles. The median second-line PFS was seven months. Third-line therapies included axitinib (24 patients) and cabozantinib (20 patients). The median PFS for axitinib and cabozantinib was six months, with comparable survival outcomes. The IMDC risk group and treatment tolerability were significant predictors of survival in multivariate analysis. Adverse events were manageable, with hypertension, fatigue, and diarrhea being the most common. Conclusion: Axitinib and cabozantinib show promise as third-line therapies post-nivolumab progression in metastatic RCC, though prospective validation is warranted. This study underscores the need for further research to establish treatment standards in this evolving landscape. Full article

(This article belongs to the Section Oncology)

16 pages, 341 KiB

Open AccessArticle

Experiences of Individual Care Workers in Oral Care of Dementia Patients

by Evelina Daugėlienė, Karolina Skučaitė, Jurgita Andruškienė, Šarūnė Barsevičienė and Eglė Žymantienė

Medicina 2024, 60(7), 1087; https://doi.org/10.3390/medicina60071087 - 2 Jul 2024

Abstract

: Objective: Dementia is one of the most common diseases in the elderly population. The aim of this study was to reveal the experiences of individual care workers performing oral care for dementia patients. The oral health of the elderly is in a [...] Read more.

: Objective: Dementia is one of the most common diseases in the elderly population. The aim of this study was to reveal the experiences of individual care workers performing oral care for dementia patients. The oral health of the elderly is in a critical state and in most cases not enough attention is paid to this problem. Material and methods: A qualitative research method was chosen for the research. The data collection instrument was a semi-structured interview, the purpose of which was to reveal the experience, knowledge, and attitude of individual care workers towards the importance of oral care and the oral hygiene habits of patients with dementia. The number of research informants was 10. The inclusion criteria were individual care workers working in social care institutions who were responsible for the personal care of dementia patients. Results: The analysis of the study showed that the main obstacles facing individual care workers in performing oral care for dementia patients are related to their cognitive disorders. For this reason, unreasonable fears of patients may arise, which also affect the proper performance of individual oral hygiene and other tasks assigned to employees. Conclusions: The results of the study showed that according the informants’ opinions it is crucial to take care of dementia patients’ oral care daily. Full article

(This article belongs to the Section Dentistry)

21 pages, 14706 KiB

Open AccessArticle

Drought and Wildfire Trends in Native Forests of South-Central Chile in the 21st Century

by Efraín Duarte, Rafael Rubilar, Francisco Matus, Claudia Garrido-Ruiz, Carolina Merino, Cecilia Smith-Ramirez, Felipe Aburto, Claudia Rojas, Alejandra Stehr, José Dörner, Francisco Nájera, Guillermo Barrientos and Ignacio Jofré

Fire 2024, 7(7), 230; https://doi.org/10.3390/fire7070230 - 2 Jul 2024

Abstract

Over the last decades, Chile has experienced a long-term drought with significant consequences for water availability, forest productivity, and soil degradation, ultimately dramatically increasing the surface of burned area. Here, we quantify the Palmer Drought Severity Index (PDSI) to ascertain the extent of [...] Read more.

Over the last decades, Chile has experienced a long-term drought with significant consequences for water availability, forest productivity, and soil degradation, ultimately dramatically increasing the surface of burned area. Here, we quantify the Palmer Drought Severity Index (PDSI) to ascertain the extent of “moisture deficiency” across the central-southern region of Chile from 2000 to 2023 to assess the drought’s relationship with the frequency of wildfires focusing on the impact of native forests. Our methodology quantifies the PDSI from the burned area data using MODIS MCD64A1 satellite imagery, validated by in situ wildfire occurrence records. The findings indicate that 85.2% of fires occurred under moderate to severe drought conditions. We identified 407,561 ha showing varying degrees of degradation due to wildfires, highlighting the critical areas for targeted conservation efforts. A significant increase in both the frequency of wildfires and the extent of the affected area in native forests was observed with the intensification of drought conditions in the 21st century within mesic to humid Mediterranean climatic zones where drought explains up to 41% of the variability in the burned area (r² = 0.41; p < 0.05). This study highlights the relationship between drought conditions and wildfire frequency, showing the paramount need to adopt comprehensive wildfire mitigation management in native forests. Full article

(This article belongs to the Special Issue The Use of Remote Sensing Technology for Forest Fire)

► Show Figures

Figure 1

15 pages, 1326 KiB

Open AccessArticle

Genomic Insights into and In Vitro Evaluation of Antimicrobial Combination Therapies for Carbapenem-Resistant Acinetobacter baumannii

by Saadia Ijaz, Farheen Ansari, Muhammad Nawaz, Hasan Ejaz, Aftab Ahmad Anjum, Aqib Saeed, Tehreem Ali, Obaid Ur Rehman, Eeshal Fatima and Tayyaba Ijaz

Medicina 2024, 60(7), 1086; https://doi.org/10.3390/medicina60071086 - 2 Jul 2024

Abstract

Background and Objectives: Acinetobacter baumannii (A. baumannii), particularly carbapenem-resistant A. baumannii (CRAB), represents a grave concern in healthcare settings and is associated with high mortality. This study aimed to conduct molecular, mutational, and phylogenetic analyses of specific genes in CRAB [...] Read more.

Background and Objectives: Acinetobacter baumannii (A. baumannii), particularly carbapenem-resistant A. baumannii (CRAB), represents a grave concern in healthcare settings and is associated with high mortality. This study aimed to conduct molecular, mutational, and phylogenetic analyses of specific genes in CRAB and evaluate the synergistic effects of selected antimicrobial combinations. Materials and Methods: Phenotypic characterization was performed on six CRAB strains by using the Modified Hodge Test (MHT) and IMP-EDTA Double-Disc Synergy Test (IMP-EDTA DDST). Carbapenemase- and metallo-beta-lactamase-encoding genes were amplified by using Polymerase Chain Reaction. Phylogenetic analysis using the MEGA 11 tool was used to determine the evolutionary relatedness of these genes. Mutational analysis was performed by using I-Mutant, MUPro, and PHD-SNP bioinformatics tools to predict mutations in the carbapenemase-encoding genes. Microdilution checkerboard titration assessed the synergistic effects of antimicrobial combinations (azithromycin–meropenem, rifampicin–meropenem, meropenem–colistin, and azithromycin–colistin) on these CRAB isolates. Results: The phenotypic characterization of six CRAB isolates revealed positive results for MHT and IMP-EDTA DDST. The molecular characterization revealed that carbapenemase- and MBL-encoding genes were present in all isolates with varying frequencies, including blaOXA-51 (100%) and blaIMP (0%). The sequence analysis revealed high evolutionary relatedness to sequences in the NCBI database. The mutational analysis identified 16 mutations, of which 1 mutation (P116L) in the blaOXA-58 gene predicted a change in the protein product, potentially contributing to carbapenem resistance. The checkerboard titration method did not reveal any synergism among the tested antimicrobial combinations against CRAB. Conclusion: This study’s findings underscore the significant challenges posed by CRAB isolates harboring multiple resistant genes in treatment. This highlights the urgent need for novel antimicrobial agents, a crucial step towards reducing mortality rates not only in Pakistan but also globally. Full article

(This article belongs to the Section Infectious Disease)

28 pages, 878 KiB

Open AccessArticle

Fault-Tolerant Tracking Control of Hypersonic Vehicle Based on a Universal Prescribe Time Architecture

by Fangyue Guo, Wenqian Zhang, Maolong Lv and Ruiqi Zhang

Drones 2024, 8(7), 295; https://doi.org/10.3390/drones8070295 - 2 Jul 2024

Abstract

An adaptive tracking control strategy with a prescribe tracking error and the convergence time is proposed for hypersonic vehicles with state constraints and actuator failures. The peculiarity is that constructing a new time scale coordinate translation mapping method, which maps the prescribe time [...] Read more.

An adaptive tracking control strategy with a prescribe tracking error and the convergence time is proposed for hypersonic vehicles with state constraints and actuator failures. The peculiarity is that constructing a new time scale coordinate translation mapping method, which maps the prescribe time on the finite field to the time variable on the infinite field, and the convergence problem of the prescribe time is transformed into the conventional system convergence problem. The improved Lyapunov function, the improved tuning function, and the adaptive fault-tolerant mechanism are further constructed. Combined with the neural network, the prescribe time tracking control of the speed subsystem and the height subsystem are realized respectively. Combined with the Barbalat lemma and Lyapunov stability theory, the boundedness of the closed-loop system is proved. The simulation results have proven that, compared with other control strategies, it can ensure that the tracking error converges to the prescribe interval in the prescribe time and meets the constraints of the whole state of the system. Full article

(This article belongs to the Special Issue Distributed Control, Optimization, and Game of UAV Swarm Systems)

► Show Figures

Figure 1

14 pages, 4162 KiB

Open AccessArticle

Study of the Safety Characteristics of Different Types of Pepper Powder (Capsicum L.)

by László Kosár, Zuzana Szabová, Richard Kuracina, Stefan H. Spitzer, Miroslav Mynarz and Bohdan Filipi

Fire 2024, 7(7), 229; https://doi.org/10.3390/fire7070229 - 2 Jul 2024

Abstract

This research was aimed at comparing the fire characteristics of different types of pepper in the context of explosion prevention. The following characteristics were studied: explosion pressure P_max and K_st at selected concentrations, ignition temperature of the deposited dust layer from [...] Read more.

This research was aimed at comparing the fire characteristics of different types of pepper in the context of explosion prevention. The following characteristics were studied: explosion pressure P_max and K_st at selected concentrations, ignition temperature of the deposited dust layer from the hot surface, and minimum ignition energy. The comparison of the chemical properties of the used types of pepper was performed using TG/DSC. The results of the measurements suggest that different types of peppers exhibit different explosion characteristics. Each sample reached the maximum value of the explosion pressure and rate of pressure rise at different concentrations. The volume of the explosion chamber used also influenced the explosion characteristics. It is a consequence of the fact that the explosion characteristics strongly depend on the mechanism of action of a particular igniter. The minimum effect on the safety characteristics was observed when measuring the minimum ignition energy and the minimum ignition temperature of the dust layer from the hot surface. The results of the measurements suggest that different types of peppers exhibit different explosion characteristics. This information should then be considered in explosion prevention. Full article

(This article belongs to the Special Issue Fire and Explosions Risk in Industrial Processes)

15 pages, 1145 KiB

Open AccessArticle

Structural, Morphological and Ferroelectric Properties of Sr-Cd Co-Doped Nickel Ferrite for Energy Storage Devices

by Huda A. Alburaih, Muhammad Ahsan ul Haq, Abdul Jabbar, Atiq ur Rehman, Amel Laref, Mohamed Musa Saad Hasb Elkhalig and Naveed Ahmad Noor

Magnetochemistry 2024, 10(7), 48; https://doi.org/10.3390/magnetochemistry10070048 - 2 Jul 2024

Abstract

Ferroelectric materials, renowned for their capacity to demonstrate spontaneous electric polarization reversible through an external electric field, are essential in numerous technological applications owing to their distinctive characteristics. For this, a series of spinel Sr-Cd co-doped nickel ferrite nanomaterials Cd₀._5−x [...] Read more.

Ferroelectric materials, renowned for their capacity to demonstrate spontaneous electric polarization reversible through an external electric field, are essential in numerous technological applications owing to their distinctive characteristics. For this, a series of spinel Sr-Cd co-doped nickel ferrite nanomaterials Cd₀._5−xSr_xNi₀.₅Fe₂O₄ (x = 0.0, 0.1, 0.2 and 0.3) were prepared through the standard sol-gel auto combustion method The XRD patterns showed that the prepared samples have a cubic spinel structure. The crystallite sizes of the samples vary from 29 to 40 nm. The morphology of prepared samples showed uniformly distributed spheres. Magnetic properties showed the soft magnetic nature of the prepared ferrites. The ferroelectric study revealed that Sr-Cd substituted ferrites exhibited the elliptical nature of ferroelectric loops at normal room temperature. The maximum polarization has been achieved at x = 0.3. The understanding of current and voltage (I–V) showed a slowly decreasing tendency of leakage current on both sides symmetrically against the increasing Sr content. The conductivity of the prepared spinel increases as a function of higher Sr doping. The real part of dielectric constant increases with increasing frequency. The materials show large elliptical loops indicating high asymmetric ferroelectric energy storage capability. Full article

20 pages, 920 KiB

Open AccessArticle

Experimental Investigation of the Performance of a Novel Ejector–Diffuser System with Different Supersonic Nozzle Arrays

by Dachuan Xu, Yunsong Gu, Wei Li and Jingxiang Chen

Fluids 2024, 9(7), 155; https://doi.org/10.3390/fluids9070155 - 2 Jul 2024

Abstract

The supersonic–supersonic ejector–diffuser system is employed to suck supersonic low-pressure and low-temperature flow into a high-pressure environment. A new design of a supersonic–supersonic ejector–diffuser was introduced to verify pressure control performance under different operating conditions and vacuum background pressure. A 1D analysis was [...] Read more.

The supersonic–supersonic ejector–diffuser system is employed to suck supersonic low-pressure and low-temperature flow into a high-pressure environment. A new design of a supersonic–supersonic ejector–diffuser was introduced to verify pressure control performance under different operating conditions and vacuum background pressure. A 1D analysis was used to predict the geometrical structure of an ejector–diffuser with a rectangular section based on the given operating conditions. Different numbers and types of nozzle plates were designed and installed on the ejector to study the realizability of avoiding or postponing the aerodynamic choking phenomenon in the mixing section. The effects of different geometrical parameters on the operating performance of the ejector–diffuser system were discussed in detail. Experimental investigation of the effects of different types of nozzle plates and the back pressures on the pressure control performance of the designed ejector–diffuser system were performed in a straight-flow wind tunnel. The results showed that the position, type and number of the nozzle plates have a significant impact on the beginning of the formation of aerodynamic choking. The geometry of the ejector and the operating conditions, especially the backpressure and inlet pressure of the ejecting stream, determined the entrainment ratio of the two supersonic streams. The experimental results showed that long nozzle-plate had a better performance in terms of maintaining pressure stability in the test section, while short a nozzle-plate had a better pressure matching performance and could maintain a higher entrainment ratio under high backpressure conditions. Full article

(This article belongs to the Topic Advanced Heat and Mass Transfer Technologies)

16 pages, 8607 KiB

Open AccessArticle

Risk Factors and Effects of Climate Lag on Vibrio Parahaemolyticus Infection in Eastern Coastal Cities of China: A Study Based on Hangzhou City

by Hangqi Ren, Ting Liu, Hao Hou, Xiaojuan Qi, Lei Fang, Yinyi Yang and Rong Ma

Foods 2024, 13(13), 2116; https://doi.org/10.3390/foods13132116 - 2 Jul 2024

Abstract

Bacterial foodborne diseases caused by Vibrio parahaemolyticus pose persistent challenges to coastal cities in China. In this study, we employed multiple logistic regression analysis and distributed lag non-linear models (DLNM) to investigate the epidemiological characteristics and associated risk factors of vibriosis in the [...] Read more.

Bacterial foodborne diseases caused by Vibrio parahaemolyticus pose persistent challenges to coastal cities in China. In this study, we employed multiple logistic regression analysis and distributed lag non-linear models (DLNM) to investigate the epidemiological characteristics and associated risk factors of vibriosis in the metropolitan area of Hangzhou from 2014 to 2018. Analysis of foodborne cases indicated that certain demographics and occupational factors, including age between 16 and 44 years; houseworkers or unemployed individuals; preference for aquatic and meat products; and dining in collective canteens or catering services contribute to an increased likelihood of V. parahaemolyticus infection. Moreover, a higher per capita GDP and exposure to high temperatures were identified as risk factors for vibriosis. This study highlights the significance of the daily mean temperature as a meteorological factor influencing V. parahaemolyticus infection, with varying lag effects observed depending on temperature conditions. At low temperatures, the risk of infection occurs after a lag of 21 days, whereas at high temperatures, the risk is highest on the same day, while the second infection risk period occurs after a lag of 21 days. These findings provide a spatiotemporal perspective of the risk analysis of foodborne diseases, with a daily timescale and street spatial scale, which contributes to the development of public health strategies and food safety protocols in coastal cities. Full article

(This article belongs to the Section Food Quality and Safety)

► Show Figures

Figure 1

20 pages, 3124 KiB

Open AccessArticle

Soy Protein Isolate Gel Subjected to Freezing Treatment: Influence of Methylcellulose and Sodium Hexametaphosphate on Gel Stability, Texture and Structure

by Xiaoyu Xia, Binyang Zhang, Yuyang Huang, Ying Zhu, Min Qu, Linlin Liu, Bingyu Sun and Xiuqing Zhu

Foods 2024, 13(13), 2117; https://doi.org/10.3390/foods13132117 - 2 Jul 2024

Abstract

Freezing affects texture and induces the loss of gel quality. This study investigated the effects of methylcellulose (MC) (0.2%, 0.4%, 0.6%) and sodium hexametaphosphate (SHMP) (0.15%, 0.3%) on the gel textural and structural properties of SPI gels before and after freezing, and explores [...] Read more.

Freezing affects texture and induces the loss of gel quality. This study investigated the effects of methylcellulose (MC) (0.2%, 0.4%, 0.6%) and sodium hexametaphosphate (SHMP) (0.15%, 0.3%) on the gel textural and structural properties of SPI gels before and after freezing, and explores the synergistic enhancement of gel texture and the underlying mechanisms resulting from the simultaneous addition of SHMP and MC to SPI gels. It was revealed that MC improved the strength of SPI gels through its thickening properties, but it could not inhibit the reduction of SPI gels after freezing. The 0.4% MC-SPI gel exhibited the best gel strength (193.2 ± 2.4 g). SHMP inhibited gel reduction during freezing through hydrogen bonding and ionic interactions; it enhanced the freezing stability of SPI gels. The addition of 0.15% SHMP made the water-holding capacity in SPI gels reach the highest score after freezing (58.2 ± 0.32%). The synergistic effect of MC and SHMP could improve the strength and the freezing stability of SPI gels. MC facilitated the release of ionizable groups within SPI, causing negatively charged SHMP groups to aggregate on the SPI and inhibit the freezing aggregation of proteins. These results provide a strong basis for the improvement of cryogenic soy protein gel performance by SHMP and MC. Full article

(This article belongs to the Section Food Engineering and Technology)

19 pages, 585 KiB

Open AccessArticle

Sausage Quality during Storage under the Partial Substitution of Meat with Fermented Oyster Mushrooms

by Meltem Boylu, Géza Hitka and György Kenesei

Foods 2024, 13(13), 2115; https://doi.org/10.3390/foods13132115 - 2 Jul 2024

Abstract

The increasing global demand for meat production, driven by a rapidly expanding population and changing dietary preferences has prompted the search for protein-rich, sustainable, and healthier meat alternatives. In this context, edible mushrooms are viewed as advantageous substitutes for meat, offering a viable [...] Read more.

The increasing global demand for meat production, driven by a rapidly expanding population and changing dietary preferences has prompted the search for protein-rich, sustainable, and healthier meat alternatives. In this context, edible mushrooms are viewed as advantageous substitutes for meat, offering a viable solution. This study aimed to investigate the effects of partially replacing (25% and 50%) pork meat in sausage samples with fermented oyster mushrooms (Pleurotus ostreatus), which were subjected to various pretreatments. Six different pretreatments were applied to fresh oyster mushrooms as follows: blanching in water, steaming, oven-cooking, microwave treatment, high hydrostatic pressure treatment, and ultraviolet light treatment. The effects of mushroom replacement on the moisture, pH, lipid oxidation, color, and textural properties of sausages during the 4-week refrigerated storage period were evaluated. The results revealed that replacing pork meat with fermented oyster mushrooms resulted in an increase in moisture content and b* values and a decrease in pH, L*, a*, and shear force values, proportional to the mushroom percentage. The lipid oxidation findings suggest that the antioxidant capabilities of fermented oyster mushrooms were influenced by the pretreatment methods applied to the mushrooms, exhibiting varying levels of effectiveness. Full article

(This article belongs to the Special Issue Mushrooms in Food Industry and Human Nutrition)

32 pages, 597 KiB

Open AccessFeature PaperReview

A Comprehensive Review on Discriminant Analysis for Addressing Challenges of Class-Level Limitations, Small Sample Size, and Robustness

by Lingxiao Qu and Yan Pei

Processes 2024, 12(7), 1382; https://doi.org/10.3390/pr12071382 - 2 Jul 2024

Abstract

The classical linear discriminant analysis (LDA) algorithm has three primary drawbacks, i.e., small sample size problem, sensitivity to noise and outliers, and inability to deal with multi-modal-class data. This paper reviews LDA technology and its variants, covering the taxonomy and characteristics of these [...] Read more.

The classical linear discriminant analysis (LDA) algorithm has three primary drawbacks, i.e., small sample size problem, sensitivity to noise and outliers, and inability to deal with multi-modal-class data. This paper reviews LDA technology and its variants, covering the taxonomy and characteristics of these technologies and comparing their innovations and developments in addressing these three shortcomings. Additionally, we describe the application areas and emphasize the kernel extensions of these technologies to solve nonlinear problems. Most importantly, this paper presents perspectives on future research directions and potential research areas in this field. Full article

(This article belongs to the Special Issue Advances in the Control of Complex Dynamic Systems)

► Show Figures

Figure 1

23 pages, 6106 KiB

Open AccessArticle

Monitoring and Reconstruction of Actuator and Sensor Attacks for Lipschitz Nonlinear Dynamic Systems Using Two Types of Augmented Descriptor Observers

by Hao Wang, Zhi-Wei Gao and Yuanhong Liu

Processes 2024, 12(7), 1383; https://doi.org/10.3390/pr12071383 - 2 Jul 2024

Abstract

Fault data injection attacks may lead to a decrease in system performance and even a malfunction in system operation for an automatic feedback control system, which has motive to develop an effective method for rapidly detecting such attacks so that appropriate measures can [...] Read more.

Fault data injection attacks may lead to a decrease in system performance and even a malfunction in system operation for an automatic feedback control system, which has motive to develop an effective method for rapidly detecting such attacks so that appropriate measures can be taken correspondingly. In this study, a secure descriptor estimation technique is proposed for continuous-time Lipschitz nonlinear cyber physical systems affected by actuator attacks, sensor attacks, and unknown process uncertainties. Specifically, by forming a new state vector composed of original system states and sensor faults, an equivalent descriptor dynamic system is built. A proportional and derivate sliding-mode observer is presented so that the system states, sensor attack, and actuator attack can be reconstructed successfully. The observer gains are obtained by using linear matrix inequality to secure robustly stable estimation error dynamics. Moreover, a robust descriptor fast adaptive observer estimator is presented as a complement. Finally, the efficacy levels of the proposed design approaches are validated using a vertical take-off and landing aircraft system. Comparison studies are also carried out to assess the tracking performances of the proposed algorithms. Full article

(This article belongs to the Special Issue Monitoring and Control of Processes in the Context of Industry 4.0)

21 pages, 1146 KiB

Open AccessArticle

Research and Application of Treatment Measures for Low-Yield and Low-Efficiency Coalbed Methane Wells in Qinshui Basin

by Lichun Sun, Zhigang Zhao, Chen Li, Ruyong Feng, Yanjun Meng and Yong Li

Processes 2024, 12(7), 1381; https://doi.org/10.3390/pr12071381 - 2 Jul 2024

Abstract

China is rich in high-grade coalbed methane resources, accounting for one-third of the total amount of coalbed methane resources. Qinshui Basin is the main high ranking coalbed methane mining basin in China. In the early stage of CBM development, low-production and low-efficiency wells [...] Read more.

China is rich in high-grade coalbed methane resources, accounting for one-third of the total amount of coalbed methane resources. Qinshui Basin is the main high ranking coalbed methane mining basin in China. In the early stage of CBM development, low-production and low-efficiency wells were formed in the process of block development because of an insufficient understanding of reservoir geological conditions. The existence of low-yield and low-efficiency wells with low output and a poor development benefit seriously restricts the efficient development of coalbed methane. In order to improve the overall development efficiency of coalbed methane fields, how to revitalize low-yield and low-efficiency wells is the main problem facing the development process of coalbed methane. With the deepening understanding of the study area geology, the formation of low-yield and low-efficiency wells has been basically identified. With the advancement of development technology, developers have the ability to retrofit some low-producing and inefficient wells. Low-production and low-efficiency wells are widely distributed. It is difficult to find the criteria for classifying low-producing and low-efficiency wells because of the great differences in geological conditions and reservoir physical properties in different blocks. In addition, the causes of a low-production and low-efficiency well are complex, as the same well is often caused by many reasons, and how to identify the causes of low-production and low-efficiency wells is difficult. In recent decades, developers have studied many methods to retrofit low-production wells, but the retrofit results are not satisfactory. How to choose an economical and efficient reservoir reconstruction method to revitalize low-production and low-efficiency wells is particularly important. This paper starts with the definition of low-production and low-efficiency wells in different blocks, combining an economic evaluation and productivity characteristics to judge whether they are low-production and low-efficiency wells, and defines the distribution of low-production and low-efficiency wells in blocks. The reasons for the formation of low-production and low-efficiency wells are analyzed with the geological characteristics, production dynamic performance, and engineering reconstruction effects. This paper makes a comparative analysis of the current relatively mature low-production and low-efficiency well treatment measures, clearly identifies the advantages and disadvantages of different treatment measures, and takes corresponding stimulation measures for different causes of low-production and low-efficiency wells. The research shows that there are 687 low-production and low-efficiency wells in block A, accounting for 69.4% of the total number of wells, and the low-production and low-efficiency wells account for a relatively large proportion; so, it is necessary to treat them. The main causes of low-production and low-efficiency wells are geology, engineering and drainage systems. The geological reason mainly refers to the low gas production of coalbed methane wells influenced by three factors: resource abundance, faults, and collapse columns. According to the different causes, three treatment measures of large-scale secondary fracturing, temporary plugging, and diversion fracturing and foam fracturing are put forward. The research method in this paper is targeted at different geological conditions so it can be used to guide the treatment of low-yield and low-efficiency wells in other CBM blocks, and it has very important significance for revitalizing the existing low-efficiency CBM assets and improving the development efficiency of CBM. Full article

(This article belongs to the Special Issue Shale Gas and Coalbed Methane Exploration and Practice)

38 pages, 766 KiB

Open AccessReview

Decoding the Role of CYP450 Enzymes in Metabolism and Disease: A Comprehensive Review

by Basma Hossam Abdelmonem, Noha M. Abdelaal, Eman K. E. Anwer, Alaa A. Rashwan, Mohamed Ali Hussein, Yasmin F. Ahmed, Rana Khashana, Mireille M. Hanna and Anwar Abdelnaser

Biomedicines 2024, 12(7), 1467; https://doi.org/10.3390/biomedicines12071467 - 2 Jul 2024

Abstract

Cytochrome P450 (CYP450) is a group of enzymes that play an essential role in Phase I metabolism, with 57 functional genes classified into 18 families in the human genome, of which the CYP1, CYP2, and CYP3 families are prominent. Beyond drug metabolism, CYP [...] Read more.

Cytochrome P450 (CYP450) is a group of enzymes that play an essential role in Phase I metabolism, with 57 functional genes classified into 18 families in the human genome, of which the CYP1, CYP2, and CYP3 families are prominent. Beyond drug metabolism, CYP enzymes metabolize endogenous compounds such as lipids, proteins, and hormones to maintain physiological homeostasis. Thus, dysregulation of CYP450 enzymes can lead to different endocrine disorders. Moreover, CYP450 enzymes significantly contribute to fatty acid metabolism, cholesterol synthesis, and bile acid biosynthesis, impacting cellular physiology and disease pathogenesis. Their diverse functions emphasize their therapeutic potential in managing hypercholesterolemia and neurodegenerative diseases. Additionally, CYP450 enzymes are implicated in the onset and development of illnesses such as cancer, influencing chemotherapy outcomes. Assessment of CYP450 enzyme expression and activity aids in evaluating liver health state and differentiating between liver diseases, guiding therapeutic decisions, and optimizing drug efficacy. Understanding the roles of CYP450 enzymes and the clinical effect of their genetic polymorphisms is crucial for developing personalized therapeutic strategies and enhancing drug responses in diverse patient populations. Full article

(This article belongs to the Section Endocrinology and Metabolism Research)

22 pages, 1777 KiB

Open AccessArticle

Obtaining Conservative Estimates of Integrated Profitability for a Single-Period Product in an Own-Branding-and-Manufacturing Enterprise with Multiple Owned Channels

by Rung-Hung Su, Chia-Ding Hou and Jou-Yu Lee

Mathematics 2024, 12(13), 2080; https://doi.org/10.3390/math12132080 - 2 Jul 2024

Abstract

The achievable capacity index (ACI) is a simple and efficient approach for estimating the profitability of newsboy-type products, wherein profitability is defined as the probability of achieving the target profit by optimizing the order quantity. At present, the ACI is applicable to single [...] Read more.

The achievable capacity index (ACI) is a simple and efficient approach for estimating the profitability of newsboy-type products, wherein profitability is defined as the probability of achieving the target profit by optimizing the order quantity. At present, the ACI is applicable to single retail stores (i.e., single demand) but not to multiple sales channels (i.e., multiple demand). This paper presents an integrated achievable capacity index (IACI) by which to measure the aggregate profitability of multiple mutually independent channels under normally distributed demand. An unbiased IACI estimator is also developed, to which is applied the Taylor expansion to approximate its sampling distribution, wherein the sizes, means, and variances of demand differ in each channel. Furthermore, overestimates due to sampling error are avoided by deriving the lower confidence bound for the IACI. This paper also provides generic tables to aid managers seeking conservative estimates of profitability. The applicability of the proposed scheme is demonstrated numerically using a real-world example involving an own-branding-and-manufacturing (OBM) enterprise with multiple owned channels. Full article

(This article belongs to the Special Issue Applied Statistics in Management Sciences)

27 pages, 736 KiB

Open AccessArticle

Optimization of Interaction with Counterparties: Selection Game Algorithm under Uncertainty

by Andrey Zaytsev, Ekaterina Mihel, Nikolay Dmitriev, Dmitry Alferyev and Ungvari Laszlo

Mathematics 2024, 12(13), 2079; https://doi.org/10.3390/math12132079 - 2 Jul 2024

Abstract

The purpose of this study is to develop a comprehensive algorithm for optimizing the interaction of economic entities with counterparties, taking into account the uncertainty of market conditions and the variety of behavioral strategies of participants. The developed algorithm aims to increase the [...] Read more.

The purpose of this study is to develop a comprehensive algorithm for optimizing the interaction of economic entities with counterparties, taking into account the uncertainty of market conditions and the variety of behavioral strategies of participants. The developed algorithm aims to increase the stability and efficiency of the interactions between the economic entity under study and its counterparties, minimizing risks and optimizing cooperative and competitive strategies within the framework of existing market relations. The methodology uses game theory to devise interaction strategies using mutual influence indices, non-cooperative game principles, and payment matrices. The model analyzes various interaction scenarios with counterparties by using payment matrices and considering both competitive and cooperative conditions. The research methodology is supplemented by the calculation of integral estimates based on a set of financial and economic indicators, enabling the assessment of the impact of various interaction strategies on the overall efficiency of an economic entity. After testing the developed models, a set of data was obtained, which can be used to optimize strategic planning and manage the interaction of economic entities with counterparties. The developed algorithm is an effective tool for improving the operational analysis of enterprises, primarily in industrial sectors. Full article

(This article belongs to the Special Issue Applications of Data Envelopment Analysis and Econometrics)

19 pages, 2734 KiB

Open AccessArticle

Coupled Simultaneous Evolution of Policy, Enterprise Innovation Awareness, and Technology Diffusion in Multiplex Networks

by Jingyi Wang, Rui Hu and Hua Xu

Mathematics 2024, 12(13), 2078; https://doi.org/10.3390/math12132078 - 2 Jul 2024

Abstract

This study comprehensively examines the coupling effect of government policies, enterprise behavior, and existing technology on the diffusion of innovative technology. Utilizing multiplex network theory, a multiplex network model is constructed to couple policy incentives, enterprise innovation consciousness, and technology diffusion. Both global- [...] Read more.

This study comprehensively examines the coupling effect of government policies, enterprise behavior, and existing technology on the diffusion of innovative technology. Utilizing multiplex network theory, a multiplex network model is constructed to couple policy incentives, enterprise innovation consciousness, and technology diffusion. Both global- and local-order parameters are introduced to characterize the interaction mechanisms between new and old technologies. By employing the microscopic Markov chain approach (MMCA), the threshold for technology diffusion is derived, theoretically revealing the mechanisms behind the diffusion of innovative technology. Considering the heterogeneity of enterprises, a numerical simulation is conducted on a scale-free network. The results indicate that, as the intensity of policy incentives increases, the threshold for technology diffusion decreases, promoting the spread of innovative technology. Additionally, the coupling relationship between existing technology and innovative technology influences the diffusion scale of the latter. The innovation behavior of enterprises further facilitates the adoption and dissemination of innovative technology. Full article

(This article belongs to the Section Financial Mathematics)

29 pages, 6468 KiB

Open AccessArticle

Trajectory Optimization for Adaptive Deformed Wheels to Overcome Steps Using an Improved Hybrid Genetic Algorithm and an Adaptive Particle Swarm Optimization

by Yanjie Liu, Yanlong Wei, Chao Wang and Heng Wu

Mathematics 2024, 12(13), 2077; https://doi.org/10.3390/math12132077 - 2 Jul 2024

Abstract

Two-wheeled mobile robots with deformed wheels face low stability when climbing steps, and their success rate in overcoming steps is affected by the trajectory. To address these challenges, we propose an improved hybrid genetic and adaptive particle swarm optimization (HGAPSO) algorithm to optimize [...] Read more.

Two-wheeled mobile robots with deformed wheels face low stability when climbing steps, and their success rate in overcoming steps is affected by the trajectory. To address these challenges, we propose an improved hybrid genetic and adaptive particle swarm optimization (HGAPSO) algorithm to optimize the deformed wheels’ trajectory for overcoming steps. HGAPSO optimizes the maximum and minimum values of the inertial weight and learning factors of the adaptive particle swarm algorithm utilizing the region-wide search capabilities of the genetic algorithm, which substantially improves the convergence speed and adaptability. Furthermore, the analysis of the motion of the deformed wheel overcoming the steps and the examination of the potential interference during the operation are used to construct a wheel’s center-of-mass route based on fifth-order Bézier curves. Comparative simulation experiments of the trajectories optimized using different optimization algorithms under the same working conditions are designed to demonstrate the efficacy of the proposed HGAPSO algorithm in optimizing the trajectory of the deformed wheel overcoming the step. Simulation experiments were conducted using the HGAPSO algorithm to optimize the trajectories of deformation wheels for overcoming steps of various sizes. These optimized trajectories were then compared to unoptimized ones. The results showed that the HGAPSO-optimized trajectories significantly improved the success rate and stability of the mobile robot in overcoming steps. Full article

20 pages, 8697 KiB

Open AccessArticle

Improved Bayesian Model Updating Method for Frequency Response Function with Metrics Utilizing NHBFT-PCA

by Jinhui Li, Zhenhong Deng, Yong Tang, Siqi Wang, Zhe Yang, Huageng Luo, Wujun Feng and Baoqiang Zhang

Mathematics 2024, 12(13), 2076; https://doi.org/10.3390/math12132076 - 2 Jul 2024

Abstract

To establish a high-fidelity model of engineering structures, this paper introduces an improved Bayesian model updating method for stochastic dynamic models based on frequency response functions (FRFs). A novel validation metric is proposed first within the Bayesian theory by using the normalized half-power [...] Read more.

To establish a high-fidelity model of engineering structures, this paper introduces an improved Bayesian model updating method for stochastic dynamic models based on frequency response functions (FRFs). A novel validation metric is proposed first within the Bayesian theory by using the normalized half-power bandwidth frequency transformation (NHBFT) and the principal component analysis (PCA) method to process the analytical and experimental frequency response functions. Subsequently, traditional Bayesian and approximate Bayesian computation (ABC) are improved by integrating NHBFT-PCA metrics for different application scenarios. The efficacy of the improved Bayesian model updating method is demonstrated through a numerical case involving a three-degrees-of-freedom system and the experimental case of a bolted joint lap plate structure. Comparative analysis shows that the improved method outperforms conventional methods. The efforts of this study provide an effective and efficient updating method for dynamic model updating based on the FRFs, addressing some of the existing challenges associated with FRF-based model updating. Full article

(This article belongs to the Special Issue Uncertainty Quantification: Latest Advances and Applications)

► Show Figures

Figure 1

17 pages, 357 KiB

Open AccessArticle

Two Schemes of Impulsive Runge–Kutta Methods for Linear Differential Equations with Delayed Impulses

by Gui-Lai Zhang and Chao Liu

Mathematics 2024, 12(13), 2075; https://doi.org/10.3390/math12132075 - 2 Jul 2024

Abstract

In this paper, two different schemes of impulsive Runge–Kutta methods are constructed for a class of linear differential equations with delayed impulses. One scheme is convergent of order p if the corresponding Runge–Kutta method is p order. Another one in the general case [...] Read more.

In this paper, two different schemes of impulsive Runge–Kutta methods are constructed for a class of linear differential equations with delayed impulses. One scheme is convergent of order p if the corresponding Runge–Kutta method is p order. Another one in the general case is only convergent of order 1, but it is more concise and may suit for more complex differential equations with delayed impulses. Moreover, asymptotical stability conditions for the exact solution and numerical solutions are obtained, respectively. Finally, some numerical examples are provided to confirm the theoretical results. Full article

(This article belongs to the Special Issue Advances in Computational Mathematics and Applied Mathematics)

► Show Figures

Figure 1

20 pages, 322 KiB

Open AccessArticle

A Study of Movable Singularities in Non-Algebraic First-Order Autonomous Ordinary Differential Equations

by Xingyu Liu

Mathematics 2024, 12(13), 2074; https://doi.org/10.3390/math12132074 - 2 Jul 2024

Abstract

We studied the movable singularities of solutions of autonomous non-algebraic first-order ordinary differential equations in the form of

y^{'} = I (y (t))

and [...] Read more.

We studied the movable singularities of solutions of autonomous non-algebraic first-order ordinary differential equations in the form of

y^{'} = I (y (t))

and

y^{'} = I_{1} (y (t)) + I_{2} (y (t)) + \dots + I_{n} (y (t))

, aiming to prove that all movable singularities of all complex solutions of these equations are at most algebraic branch points. This study explores the use of the constructing triangle method to analyze complex solutions of autonomous non-algebraic first-order ordinary differential equations. For complex solutions in the form of

y = w + i v

, we treat the constructing triangle method as a way to construct a right-angled triangle in the complex plane, with the lengths of the adjacent sides being w and v. We use the definitions of the trigonometric functions sin and cos (the ratio of the adjacent side to the hypotenuse) to represent the trigonometric functions of complex solutions

y = w + i v

. Since the movable singularities of the inverse functions of trigonometric functions are easy to analyze, the properties of the movable singularities of the complex solutions are then easy to deal with. Full article

(This article belongs to the Section Difference and Differential Equations)

► Show Figures

Figure 1

Recent Articles

Open Access Journals

Highly Accessed Articles

Latest Books

News

Blog Posts

Topics

Selected Special Issues

Selected Collections

Journals by Subject

Further Information

Guidelines

MDPI Initiatives

Follow MDPI