Basic Design Constraints Research Articles

Іноваційні способи енергопідведення у процесах сушіння термолабільної сировини

Обумовлено причини зростання обсягів сушіння рослинної сировини. Визначено актуальність пошуку та дослідження нових способів енергопідведення в процесах сушіння рослинної сировини. Показано основні переваги мікрохвильового сушіння порівняно з традиційними конвенційними технологіями сушіння. Визначено основні недоліки та обмеження мікрохвильового сушіння. Показано зв'язок теми дослідження з напрямами наукової роботи кафедри процесів, обладнання та енергетичного менеджменту. Обрано робочу гіпотезу про взаємодію мікрохвильового поля з вологою в капілярно–пористих структурах. Визначено відмінності в процесі енергопідведення при мікрохвильовому та конвекційному сушінні. Визначено основні конструктивні обмеження для дизайну мікрохвильових сушильних апаратів. Описано обсяг та зміст проведених раніше досліджень. Приведено узагальнений аналіз результатів дослідження мікрохвильового сушіння для різних видів рослинної сировини. Обґрунтовано вибір апаратурної схеми установки для сушіння рослинної сировини в потоці. Визначено основні конструктивні рішення та обмеження, що визначають конструкцію мікрохвильової сушильної установки для рослинних матеріалів. Описано конструкцію та принцип дії дослідної стрічкової мікрохвильової сушильної установки створеної для проведення дослідження. Описано порядок проведення експериментального мікрохвильового сушіння насіння соняшника. Визначено основні залежності процесу мікрохвильового сушіння соняшника. Досліджено залежність між швидкістю вологовидалення та потужністю електромагнітного підведення енергії а також тривалістю сушіння. Визначено основні переваги комбінованого сушіння з використанням мікрохвильового та інфрачервоного випромінювання. Описано конструкцію та принцип дії установки для дослідження процесу вологовидалення при інфрачервоному сушіння. Визначено залежності кінетики процесу від величини енергопідведення та тривалості енергетичного впливу. Приведено аналіз отриманих результатів. Надано обґрунтування для наступного етапу дослідження.

Optimum Tendon Placement for Post Tensioned S.S. Beam with Variable Eccentricity

A challenging problem for a direct search design methods was introduced in this work. Pattern Search PS method was used to find the optimum designed section of a prestressed simply supported post tensioned beam with variable tendon eccentricity. Flexural and geometrical design constraints were used to get the optimum sectional properties of the beam. Then, new constraints concerning the placement of the tendon through the longitudinal section of the beam were introduced and involved through finding the optimum results. A single objective function was used since a multi objective optimization procedure could not be run with nonlinear constraints, and optimizing a post tensioned beam with variable eccentricity represents a highly constraints problem. Another optimization method was used here only to check the validity of the procedure adopted using PS, the results were compared for the methods and a good agreement were found between them. Apparently, using the additional constraints of the tendon placement causes a lot of difficulties to find the optimum results, as it was noticed through the elapsed time of the solution, although, both methods gave a reliable and practical optimum values, and this is due to the robust use of the design constraints to limit the optimum designed variables within the ACI code 2011 limits. Increasing the efficiency of the solution was gained through using a lot of design constraints, in addition to the basic design constraints needed in the flexural design, to avoid trapping in local optima.

Parallelized edge-based droplet generation (EDGE) devices

We here report on three parallelized designs of the new edge-based droplet generation mechanism, which, unlike existing mechanisms, produces many equally sized droplets simultaneously at a single droplet formation unit. Operation of the scaled-out systems is straight forward; only the oil inlet pressure has to be controlled to let all the units produce oil droplets, given certain basic design constraints. For systems with a typical nozzle depth of 1.2 microm, the mean droplet diameter is 7.5 microm and the coefficient of variation is below 10%. The number of droplets that is formed per unit can easily be increased by increasing the length of the unit. The stable pressure range in which monodisperse droplets are formed can be extended by small adjustments to the design. Overall, the EDGE devices are simple in design and robust in use, making them suitable for massive outscaling.

Algorithm to Optimize Code Size and Energy Consumption in Real Time Embedded System

Processor is an important computing element in portable battery operated real time embedded system and it consumes most of the battery energy. Energy consumption, processor memory space are considered as basic design constraints in ARM based system and heuristic algorithm is developed for energy consumption as well as memory space management. This Algorithm includes rate monotonic fixed priority task scheduling scheme, DVS, ARM’s Normal /Thumb mode, execution time, and number of execution cycles, which are analytically related with energy consumption. Mathematical modeling and simulation of Heuristic algorithm is done using MATLAB. This gives optimized code size, execution time, energy consumption of each task / whole system and proves a novel strategy in the field of software related energy optimization and real time embedded system design.

Dynamic analysis of LCC-type parallel resonant converter operating in discontinuous current mode

A discrete time-domain model for the LCC-type parallel resonant converter, operating in discontinuous current mode (DCM), is derived. This model, which makes use of some practical approximations, simplifies the calculations, reduces the computer simulation time and is adequate to predict some of the basic design constraints (peak component stresses, etc.) which are governed by the dynamics of the converter during large-signal transients. PROMATLAB software was used to solve the discrete-model equations on the computer. Theoretical results are verified by SPICE simulation and experiments. An approximate small-signal model is also derived and used to predict the small-signal behaviour of the converter.

Electrostatic discharge issues in electric vehicles

Electrostatic discharge (ESD) is an important issue in any motor vehicle. Anecdotal reports abound of cars with spark ignition hazards because of fuel tank designs, and even toll collectors reluctant to collect money by hand from certain late model cars. As electric vehicles move from the laboratory and test track to the production floor and showroom, ESD concerns take on a new context and become more critical. In this paper, the attributes of electric vehicles that give rise to concerns about ESD are introduced. When the concerns are taken into account, certain basic design constraints become evident. A candidate design is analyzed for its ESD properties. Some common design practices, especially the practice of isolating the battery bus, can create reliability problems because of ESD.

Silicon solar cells: evolution, high-efficiency design and efficiency enhancements

With a history dating back over 50 years, silicon solar cells were amongst the first bipolar silicon devices demonstrated. Notwithstanding this long history, the last ten years have seen rapid progress in both the efficiency of experimental devices and in the understanding of basic design constraints. The evolution of silicon cell design over the last 50 years is described and the features of current high-efficiency devices are discussed in some detail. With energy conversion efficiencies above 23%, these devices are now approaching basic limits for conventional homojunction cells. The potential for substantially increasing cell performance above these limits, by taking advantage of concepts such as the impurity photovoltaic effect, the incorporation of alloys and superlattices, and tandem cells based on silicon, is discussed.

The general problem of data return from deep space

A summary of the essential data system parameters for the Surveyor, Lunar Orbiter Pioneer, and Mariner projects is given in Table III. Because of the different mission objectives and basic design constraints, there is little correlation among the various projects and basic design constraints, there is little correlation among the various left to right, and Mariner probably represents the most sophisticated approach to data retrieval from deep space of the systems considered here. Three of the projects represent extremely successful data system designs, each of which has been proven on a considerable number of space missions. The Mariner 1969 spacecraft has yet to be launched, but the succcess of preceding Mariners affords some confidence in the basic design philosophy.