Machines

787 KiB

Open AccessArticle

Software Architecture and Framework for Programmable Logic Controllers: A Case Study and Suggestions for Research

by E. George Walters and Eric J. Bryla

Machines 2016, 4(2), 13; https://doi.org/10.3390/machines4020013 - 22 Jun 2016

Cited by 3 | Viewed by 8389

Programmable Logic Controllers (PLCs) are widely used for control and automation of machines and processes, so the quality of PLC software has a direct impact on production efficiency. This paper describes a PLC program for a food production line that was completely rewritten [...] Read more.

Programmable Logic Controllers (PLCs) are widely used for control and automation of machines and processes, so the quality of PLC software has a direct impact on production efficiency. This paper describes a PLC program for a food production line that was completely rewritten using a different software architecture and framework. The PLC hardware and the production line equipment were not changed, so this project provides an opportunity to quantify the impact of different PLC software architecture on production efficiency. The average number of cases of products produced per production hour during the first ten months with the new program was 6.1% higher than the average during the previous ten months with the old program. PLC software, unlike most other software, is often used by the end-user for troubleshooting. In this case, a relatively simple architecture and framework that favors the end-user significantly improved production efficiency over a more sophisticated architecture and framework that favors the software developer. Suggestions for further research on software architecture and framework are given. Full article

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3633 KiB

Open AccessArticle

Z-Damper: A New Paradigm for Attenuation of Vibrations

by José Luis Pérez-Díaz, Ignacio Valiente-Blanco and Cristian Cristache

Machines 2016, 4(2), 12; https://doi.org/10.3390/machines4020012 - 15 Jun 2016

Cited by 20 | Viewed by 5763

Abstract

Magnetic linear gear provides a new and unique opportunity for coupling mechanical impedances and optimizing vibration damping. In the present paper a new magneto-mechanical vibration damper (the so-called Z-damper) is described. Its expected theoretical dynamic behavior shows a particularly high damping capability, a [...] Read more.

Magnetic linear gear provides a new and unique opportunity for coupling mechanical impedances and optimizing vibration damping. In the present paper a new magneto-mechanical vibration damper (the so-called Z-damper) is described. Its expected theoretical dynamic behavior shows a particularly high damping capability, a low frequency, as well as an optimal behavior for high frequencies. Full article

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1314 KiB

Open AccessArticle

Performance Evaluation of a Prototyped Breadfruit Seed Dehulling Machine

by Nnamdi Anosike, Emmanuel Brown and Chukwnonso Maduka

Machines 2016, 4(2), 11; https://doi.org/10.3390/machines4020011 - 06 May 2016

Cited by 3 | Viewed by 5781

Abstract

The drudgery involved in dehulling breadfruit seed by traditional methods has been highlighted as one of the major problems hindering the realization of the full potential of breadfruit as a field to food material. This paper describes a development in an African breadfruit [...] Read more.

The drudgery involved in dehulling breadfruit seed by traditional methods has been highlighted as one of the major problems hindering the realization of the full potential of breadfruit as a field to food material. This paper describes a development in an African breadfruit seed dehulling machine with increased throughput of about 70% above reported machines. The machine consists of a 20 mm diameter shaft, carrying a spiral wound around its circumference (feeder). The feeder provides the required rotational motion and turns a circular disk that rotates against a fixed disk. The two disks can be adjusted to maintain a pre-determined gap for dehulling. An inbuilt drying unit reduces the moisture content of the breadfruit for easy separation of the cotyledon from the endosperm immediately after the dehulling process. The sifting unit that separates the shell from the seed is achieved in this design with an electric fan. The machine is design to run at a speed of 250 rpm with an electric motor as the prime mover. The dehulling efficiency up to 86% and breakage of less than 1.3% was obtained at a clearance setting of 12.4 mm between disks. A sifting efficiency of 100% was achieved. Based on the design diameter and clearance between the dehulling disks, the machine throughput was 216 kg/h with an electric power requirement of 1.207 kW. Full article

(This article belongs to the Special Issue Agricultural Machinery)

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336 KiB

Open AccessArticle

A Novel Modelling Approach for Condensing Boilers Based on Hybrid Dynamical Systems

by Harish Satyavada and Simone Baldi

Machines 2016, 4(2), 10; https://doi.org/10.3390/machines4020010 - 05 Apr 2016

Cited by 25 | Viewed by 6449

Abstract

Condensing boilers use waste heat from flue gases to pre-heat cold water entering the boiler. Flue gases are condensed into liquid form, thus recovering their latent heat of vaporization, which results in as much as 10%–12% increase in efficiency. Modeling these heat transfer [...] Read more.

Condensing boilers use waste heat from flue gases to pre-heat cold water entering the boiler. Flue gases are condensed into liquid form, thus recovering their latent heat of vaporization, which results in as much as 10%–12% increase in efficiency. Modeling these heat transfer phenomena is crucial to control this equipment. Despite the many approaches to the condensing boiler modeling, the following shortcomings are still not addressed: thermal dynamics are oversimplified with a nonlinear efficiency curve (which is calculated at steady-state); the dry/wet heat exchange is modeled in a fixed proportion. In this work we cover these shortcomings by developing a novel hybrid dynamic model which avoids the static nonlinear efficiency curve and accounts for a time-varying proportion of dry/wet heat exchange. The procedure for deriving the model is described and the efficiency of the resulting condensing boiler is shown. Full article

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Machines, Volume 4, Issue 2 (June 2016) – 4 articles

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