Inventions, Volume 3, Issue 2 (June 2018) – 20 articles

We demonstrate a simple, flexible and cost-effective system to automatize most of the kinematic mounts available nowadays on the market. It combines 3D-printed components, an Arduino board, stepper motors and simple electronics. The developed system can control up to ten stepper motors independently and simultaneously using commands sent through the serial port, and it is suitable for applications where optical realignment using flat mirrors is required on a periodic basis. Full article

In this study, we investigate the interfacial droplet jetting characteristics and thermal stability of a focused surface acoustic wave device (F-SAW). An F-SAW device capable of generating a 20 MHz surface acoustic wave by applying sufficient radio frequency power (2–19 W) on a 128°-rotated YX-cut piezoelectric lithium niobate substrate for interfacial droplet jetting is proposed. The interfacial droplet jetting characteristics were visualized by a shadowgraph method using a high-speed camera, and a heat transfer experiment was conducted using K-type thermocouples. The interfacial droplet jetting characteristics (jet angle and height) were analyzed for two different cases by applying a single interdigital transducer and two opposite interdigital transducers. Surface temperature variations were analyzed with radio frequency input power increases to evaluate the thermal stability of the F-SAW device in air and water environments. We demonstrate that the maximum temperature increase of the F-SAW device in the water was 1/20 of that in the air, owing to the very high convective heat transfer coefficient of the water, resulting in prevention of the performance degradation of the focused acoustic wave device. Full article

Gas water heaters take a major part in the Chinese water heater market, while the existing water heater have either low efficiency because of the single utilization of energy or the high failure rate that is caused by low temperature corrosion. A new structure of heat exchanger in the gas water heater is proposed is this article, the heat transfer method of which is not only forced convection, but also phase change heat transfer, which provides a higher heat transfer coefficient in condition of the same heat exchange area, and consequently promote the efficiency of the heat exchanger. An experimental study is carried out to compare the difference between the new water heater and the existing one on efficiency, and result shows that the new water heater is 6% higher in efficiency. Besides, this kind of water heater has a gentle temperature change when a sudden decrease or increase of gas flow rate occurs. An economic analysis is produced in order to predict the economic efficiency of the new heat exchanger. As a result, the new heat exchanger of the water heater can significantly promote the heat transfer efficiency and decrease the failure rate, and it is more economic efficient than the existing one. Full article

Thermal radiation is the only heat transfer mechanism with vacuum compatibility, and it carries energy at light speed. These advantages are taken in this work to design an oven for smart phone panels. The temperature of panels is acquired from a numerical method based on finite-difference method. The space configuration of the heating lamps as well as the relative distance between lamps and the panel are control factors for optimization. Full-factorial experiments are employed to identify the main effects from each factor. A fitness function Q considering both temperature uniformity of the panel and the heating capability of the ovens is proposed. The best oven among 27 candidates is able to raise panel temperature significantly with high uniformity. Full article

Taylor segments, as a common feature in two- or multi-phase microflows, are a strong flow pattern candidate for applications when enhanced heat or mass transfer is particularly considered. A thin film that separates these segments from touching the solid channel and the flow fields near and inside the segment are two key factors that influence (either restricting or improving) the performance of heat and mass transfer. In this numerical study, a computational fluid dynamics (CFD) method and dense carbon dioxide (CO₂) and water are applied and used as a fluid pair, respectively. One single flowing liquid or supercritical CO₂ drop enclosed by water is traced in fixed frames of a long straight microchannel. The thin film, flow fields near and within single CO₂ drop, and interfacial distributions of CO₂ subjected to diffusion and local convections are focused on and discussed. The computed thin film is generally characterized by a thickness of 1.3~2.2% of the channel width (150 µm). Flow vortexes are formed within the hydrodynamic capsular drop. The interfacial distribution profile of CO₂ drop is controlled by local convections near the interface and the interphase diffusion, the extent of which is subject to the drop size and drop speed as well. Full article

An integrated system consisting of a paper-based chip and a smart detection device is proposed for determining the human serum creatinine concentration based on Jaffé reaction theory. In the proposed approach, the reaction zone of the paper-based chip is implanted with picric acid and NaOH reagent and dried at 35 °C for 20 min. Human serum creatinine is dripped onto the reaction zone of the chip. A Jaffé reaction is induced by heating the chip at 37 °C for 5 min and the creatinine concentration is then derived by analyzing the RGB (red, green and blue) intensity of the resulting Janovsky complex using self-written analysis software installed on a smartphone. The validity of the proposed method is demonstrated using control samples with creatinine concentrations ranging from 0.2~8 mg/dL. The detection results obtained for 32 real-world creatinine samples are shown to be in excellent agreement with those obtained using a standard macroscale method (R² = 0.9994). Overall, the results show that the proposed system provides a compact, low-cost and reliable approach for human serum creatinine concentration detection. Full article

A major goal of the development of internal combustion (IC) engines continues to be higher performance and efficiencies. A major aspect of achieving higher performance and efficiencies is based on fundamental thermodynamics. Both the first and second laws of thermodynamics provide strategies for and limits to the thermal efficiencies of engines. The current work provides three examples of the insights that thermodynamics provides to the performance and efficiencies of an IC engine. The first example evaluates low heat rejection engine concepts, and, based on thermodynamics, demonstrates the difficulty of this concept for increasing efficiencies. The second example compares and contrasts the thermodynamics associated with external and internal exhaust gas dilution. Finally, the third example starts with a discussion of the Otto cycle analysis and explains why this is an incorrect model for the IC engine. An important thermodynamic property that is responsible for many of the observed effects is specific heat. Full article

The design of a micro multi-channel heat sink to achieve the minimum thermal resistance is the purpose of this study. The numerical package is employed by using the genetic algorithm to process the heat dissipation optimization of the micro multi-channel heat sink (the genetic algorithm employs the numerical package). The variables of this optimal design include channel number, channel aspect ratio and the ratio of channel width to pitch, as well as considering the weight of this micro channel heat sink in the optimal design process. Therefore, this optimization is a multi-objective function design. The results show that the thermal resistance is decreased as 0.144 W/K, and the weight of this micro channel heat sink can be decreased, individually or simultaneously. Full article

Conversion of low-grade waste heat to electrical energy paves the way to reducing environmental pollution. This work focuses on the experimental study of an organic Rankine cycle (ORC) with an n-hexane working fluid and radial turbine expander. The heat source is varied from 120 to 190 °C with a mass flow rate of 0.10 to 0.50 kg/s and pressure between 12 and 15 bar. The heat-source temperature has a direct impact on turbine performance. Increase in the mass flow rate of the working fluid led to an increase in pressure and temperature at the turbine inlet. The rise in turbine speed enhanced electrical efficiency while cutting down isentropic efficiency. The optimum speed of the turbine increased with increasing in turbine inlet temperature. Superheating leads to an increase in power along with a decrease in isentropic efficiency. The thermal efficiency followed an increasing trend when there was an increase in turbine inlet temperature and mass flow rate and decreased with an increase in turbine speed. The electrical efficiency increased for all three cases. The system was found to have a highest thermal efficiency of 5.57% with a power of 1.75 kW. Based on the experimental results, it can be concluded that an ORC with n-hexane as the working fluid and a radial turbine as the expander can be used in low-temperature waste heat recovery systems to produce power. Full article

We report a screw-like package design for an embeddable distributed optical fiber strain sensor for civil engineering applications. The screw-like structure is the exterior support for an optical fiber sensor. The bare optical fiber is embedded and secured in a longitudinal groove of the screw-like package using a rigid adhesive. Our packaging scheme prevents damage to the bare optical fiber and ensures that the packaged sensor is accurately and optimally sensing strain fields in civil structures. Moreover, our screw-like design has an equal area in a cross-section perpendicular to and along the screw axis, so strain field distributions are metered faithfully along the length of the embedded optical fiber. Our novel screw-like package optical fiber sensor, interfaced to a Rayleigh scattering-based optical frequency domain reflectometer system enables undistorted, accurate, robust, and spatially-distributed strain measurements in bridges, tunnels, pipelines, buildings, etc. along structural dimensions extending from centimeters to kilometers. Full article

Light induced three dimensional (3D) printing techniques generally use printable formulations that are based on acrylic monomers because of their fast reactivity, which is balanced with their good final properties. However, the possibility to enlarge the palette of 3D printable materials is a challenging target. In this work, hybrid printable formulations that are based on acrylic and epoxy resins are presented and their printability on DLP (Digital Light Processing) machines is demonstrated. Hexanediol diacrylate (HDDA) and an epoxy resin—3,4-Epoxycylohexylmethyl-3′,4′-epoxycyxlohexane carboxylate (CE)—in different ratios are used and the influence of a bridging agent, Glycidyl methacrylate (GMA), is also investigated. The reactivity of the different active species during irradiation is evaluated and the mechanical properties, including the impact toughness, the thermo-mechanical properties, and the volumetric shrinkage, are studied on printed samples. Full article

Extended surfaces or fins offer an efficient solution in many engineering situations that demand a higher heat transfer, including cooling gas-turbine components and electronic chips via internal convective flows. However, fins require a higher active surface area for higher heat transfer, which may not be always feasible in a confined environment. A feasible solution to enhance heat transfer from fins can be the use of nanofluids, which are the combination of a fluid base and nanoparticles. The main purpose of this study is, therefore, to optimize a rectangular fin intruded into the mixed convective confined space filled with a nanofluid and by means of constructal design. Here, a two-dimensional macroscopic numerical model has been developed for Al₂O₃–water nanofluid to investigate the heat transfer and fluid flow inside a square confined-space with an intruded rectangular fin and to optimize the fin geometry for maximizing the heat transfer using the constructal design method. The flow fields, temperature fields, heat transfer rates, and the transition from forced to mixed convection are examined for different values of Rayleigh and Reynolds numbers for various fin geometries in order to maximize the heat transfer from the fin to the surrounding nanofluid flow. The outcome of this study provides important insights into the constructal design method for the confined environment, which would be beneficial in developing novel fin geometries with enhanced and controlled heat-transfer for engineering problems, including cooling gas-turbine components and electronic chips. Full article

This paper presents a solution for monitoring of solar ultraviolet (UV) exposure and alerting about risks in real time. The novel system provides smart personalized indications for solar radiation protection. The system consists of a sensing device and a mobile application. The sensing device monitors solar radiation in real time and transmits the values wirelessly to a smart device, in which the mobile application is installed. Then, the mobile application processes the values from the sensory apparatus, based on a fuzzy expert system (FES) created from personal information (hair and eye color, tanning and burning frequency), which are entered by the user answering a short questionnaire. The FES provides an estimation of the recommended time of safe exposure in direct sunlight. The proposed system is designed to be portable (a wearable sensing device and smartphone) and low cost, while supporting multiple users. Full article

The objective of this study is to use the vibration signal features of spindles during the cutting processing to identify the different milling statuses in cases of diverse tooling parameter combinations. Accelerometers were placed on a spindle to measure vibration behaviors, and the milling status could be divided into idle cutting, initial feeding, and stable cutting. Vibration signal processing and analysis were conducted in the time domain, as well as in the frequency domain. The original vibration measurements were separated using empirical mode decomposition (EMD) in the time domain, so that the signal features could be extracted in certain frequency bands and the useless signal components and trends could be removed. Multi-scale entropy (MSE) and root mean square (RMS) were computed to extract the time domain features. In the frequency domain, the specific intrinsic mode functions (IMFs) that were decomposed using the EMD method were analyzed by fast fourier transform (FFT) and a frequency normalization technique to extract the features of apparent physical representations. The Fisher scores (FS) of the extracted features are calculated to select the high-priority signal features. The selected high-priority signal features are utilized to identify the different milling statuses through a support vector machine (SVM). The results show that an identification accuracy of 98.21% could be obtained at the Z axis, and the average accuracy would be 95.91% for the three axes combination. Full article

Over the last century, substantial advances have been made, based on improved understanding of the requirements of grinding processes, machines, control systems, materials, abrasives, wheel preparation, coolants, lubricants, and coolant delivery. This paper reviews a selection of areas in which the application of scientific principles and engineering ingenuity has led to the development of new grinding processes, abrasives, tools, machines, and systems. Topics feature a selection of areas where relationships between scientific principles and new techniques are yielding improved productivity and better quality. These examples point towards further advances that can fruitfully be pursued. Applications in modern grinding technology range from high-precision kinematics for grinding very large lenses and reflectors through to medium size grinding machine processes and further down to grinding very small components used in micro electro-mechanical systems (MEMS) devices. The importance of material issues is emphasized for the range of conventional engineering steels, through to aerospace materials, ceramics, and composites. It is suggested that future advances in productivity will include the wider application of artificial intelligence and robotics to improve precision, process efficiency, and features required to integrate grinding processes into wider manufacturing systems. Full article

E-textiles (electronic textiles) are fabrics that possesses electronic counterparts and electrical interconnects knitted into them, offering flexibility, stretchability, and a characteristic length scale that cannot be accomplished using other electronic manufacturing methods currently available. However, knitting is only one of the technologies in e-Textile integration. Other technologies, such as sewing, embroidery, and even single fiber-based manufacture technology, are widely employed in next-generation e-textiles. Components and interconnections are barely visible since they are connected intrinsically to soft fabrics that have attracted the attention of those in the fashion and textile industries. These textiles can effortlessly acclimatize themselves to the fast-changing wearable electronic markets with digital, computational, energy storage, and sensing requirements of any specific application. This mini-review focuses on recent advances in the field of e-textiles and focuses particularly on the materials and their functionalities. Full article

In this study, a bio-inspired dung beetle robot was developed that emulated the dung rolling motion of the dung beetle. Dung beetles, which can roll objects up to 1000 times their own body weight, are one of the strongest insect species in the world. While the locomotion of many insects, such as cockroaches, inchworms, and butterflies, has been studied widely, the locomotion of dung beetles has rarely been given attention. Here, we report on the development of a dung beetle robot made specifically to investigate dung-rolling behavior and to determine and understand the underlying mechanism. Two versions of the robot were built, and the leg trajectories were carefully designed based on kinematic analysis. Cylinder and ball rolling experiments were conducted, and the results showed that the dung beetle robot could successfully and reliably roll objects. This further suggests that the dung beetle robot, with its current morphology, is capable of reliably rolling dung without the need for complex control strategies. Full article

Zebrafish has an advantage of optical clarity within the body during its early developmental stage. Therefore, organs, including the heart, can be observed and analyzed in a non-invasive manner. Previously, heart rate measurement was analyzed by a complicated system, programming language, fluorescence transgenic zebrafish, or expensive setup that was not feasible and practical. In this study, we established a simple dissecting microscope with Charge-coupled Device (CCD) to capture the signal of heartbeat, and used ImageJ software as an open source platform to analyze cardiac rhythm for the atrium and the ventricle. We subjected astemizole to zebrafish embryos, and applied our apparatus to precisely detect heart arrhythmia (Atrium–Ventricle block) induction. In other words, we provided a simple, economical, and reliable method to measure cardiac rhythm in zebrafish embryos, which is able to evaluate whether cardiac rhythm is affected by chemical compounds. Full article

A cost-effective, robust and embeddable optical interferometric strain sensor with nanoscale strain resolution is presented in this paper. The sensor consists of an optical fiber, a quartz rod with one end coated with a thin gold layer, and two metal shells employed to transfer the strain and orient and protect the optical fiber and the quartz rod. The optical fiber endface, combining with the gold-coated surface, forms an extrinsic Fabry–Perot interferometer. The sensor was firstly calibrated, and the result showed that our prototype sensor could provide a measurement resolution of 30 nano-strain (nε) and a sensitivity of 10.01 µε/µm over a range of 1000 µε. After calibration of the sensor, the shrinkage strain of a cubic brick of mortar in real time during the drying process was monitored. The strain sensor was compared with a commercial linear variable displacement transducer, and the comparison results in four weeks demonstrated that our sensor had much higher measurement resolution and gained more detailed and useful information. Due to the advantages of the extremely simple, robust and cost-effective configuration, it is believed that the sensor is significantly beneficial to practical applications, especially for structural health monitoring. Full article