Beta-Conversion, Efficiently

Type-checking in dependent type theories relies on conversion, i.e. testing given lambda-terms for equality up to beta-evaluation and alpha-renaming. Computer tools based on the lambda-calculus currently implement conversion by means of algorithms whose complexity has not been identified, and in some cases even subject to an exponential time overhead with respect to the natural cost models (number of evaluation steps and size of input lambda-terms). This dissertation shows that in the pure lambda-calculus it is possible to obtain conversion algorithms with bilinear time complexity when evaluation is carried following evaluation strategies that generalize Call-by-Value to the stronger case required by conversion

Rapid manufacturing technique used in the development of a regenerative pump impeller

This paper presents a method of rapid manufacture used in the development of a regenerative pump impeller. Rapid manufacturing technology was used to create complex impeller blade profiles for testing as part of a regenerative pump optimisation process. Regenerative pumps are the subject of increased interest in industry. Ten modified impeller blade profiles, from the standard radial configuration, were evaluated with the use of computational fluid dynamics and experimental testing. Prototype impellers were needed for experimental validation of the CFD results. The manufacture of the complex blade profiles using conventional milling techniques is a considerable challenge for skilled machinists. The complexity of the modified blade profiles would normally necessitate the use of expensive CNC machining with 5 axis capability. With an impeller less than 75 mm in diameter and a maximum blade thickness of 1.3mm, a rapid manufacturing technique enabled production of complex blade profiles that were dimensionally accurate and structurally robust enough for testing. As more advanced rapid prototyping machines become available in the study in the future, e.g. 3D photopolymer jetting machine, the quality of the parts particularly in terms of surface finish will improve and the amount of post processing operations will reduce. This technique offers the possibility to produce components of increased complexity whilst ensuring quality, strength, performance and speed of manufacture. The ability to manufacture complex blade profiles that are robust enough for testing, in a rapid and cost effective manner is proving essential in the overall design optimisation process for the pump

Research in the mechanization of black locust renewal and planting

Nowadays, the black locust (Robinia pseudoacacia) is the most current and the most widely used tree species in Hungary. Due to its penetration and the wide variety of application it’s worth to examine the different mechanization options of the reforestation technologies and their costs. We provided our research in the area of Nyírerdő Nyírségi Erdészeti Zrt. According to the tests it can be said, that the cost of the reforestations with root ripping is the most favourable and the reforestation or regeneration with planting costs the most. The disadvantage of the regeneration with root ripping is, that after its multiple application it can be observed the significantly degradation of the assortment composition and of the tree utilization income

Research in the mechanization of black locust renewal and planting

Nowadays, the black locust (Robinia pseudoacacia) is the most current and the most widely used tree species in Hungary. Due to its penetration and the wide variety of application it’s worth to examine the different mechanization options of the reforestation technologies and their costs. We provided our research in the area of Nyírerdő Nyírségi Erdészeti Zrt. According to the tests it can be said, that the cost of the reforestations with root ripping is the most favourable and the reforestation or  regeneration with planting costs the most. The disadvantage of the regeneration with root ripping is, that after its multiple application it can be observed the significantly degradation of the assortment composition and of the tree utilization income

Development of a regenerative pump impeller using rapid manufacturing techniques

This paper presents a method of rapid manufacture used in the development of a regenerative pump impeller. Rapid manufacturing technology was used to create complex impeller blade profiles for testing as part of a regenerative pump optimisation process. Regenerative pumps are the subject of increased interest in industry. Ten modified impeller blade profiles, relative to the standard radial configuration, were evaluated with the use of computational fluid dynamics and experimental testing. Prototype impellers were needed for experimental validation of the CFD results. The manufacture of the complex blade profiles, using conventional milling techniques, is a considerable challenge for skilled machinists. The complexity of the modified blade profiles would normally necessitate the use of expensive CNC machining with 5 asis capability. With an impeller less than 75mm in diameter and a maximum blade thickness of 1.3mm, a rapid manufacturing technique enabled production of complex blade profiles that were dimensionally accurate and structurally robust enough for testing. As more advanced rapid prototyping machines become available in the study in the future, e.g. 3D photopolymer jetting machine, the quality of the parts, particularly in terms of surface finish, will improve and the amount of post processing operations will reduce. This technique offers the possibility to produce components of increased complexity whilst ensuring quality, strength, performance and speed of manufacture. The ability to manufacture complex blade profiles that are robust enough for testing, in a rapid and cost effective manner is proving essential in the overall design optimisation process for the pump

Breaking Ranks: On Military Spending, Unions Hear a Different Drummer

[Excerpt] What remains to be seen is whether the labor movement\u27s study of military spending will uncover the unions\u27 material self-interest in reducing it, and in conveying that interest to the membership. For besides its general damage to the economy, which is now recognized even by many conservatives, the big, endless military buildup also threatens to inflict fatal damage on the trade union movement and its individual unions—not just indirectly but directly and concretely, in the form of fewer members, fewer contracts, fewer organizing victories, and less political power for working people. In effect, the Reagan Administration\u27s plan to boost military spending in the 1980s is also a program for the structural dismantling of the trade union movement

Повышение Эффективности Основной Обработки Почвы В Засушливых Районах Российской Федерации

In the Russian Federation, large farmland areas are located in arid regions characterized by the sharply continental climate, strong winds, and insufficient rainfall. In such areas, the technology of basic nonmoldboard cultivation is widely used as a way of accumulating and preserving moisture in the soil. The specifics of this technology consists of continuous crumbling of the cultivated arable layer without soil overturning with the maximum preservation of stubbles and crop residues on the daylight surface of the field. In arid areas, subsurface tillage tools are widely used for continuous loosening of the arable layer: subsurface plows and moldboard plows with CibIME – LP-0,35 racks installed instead of housings. As a result of the conducted studies, the problem of improving the efficiency of the basic nonmoldboard cultivation in the fields in the arid agricultural regions has been solved through improving the operational and technological parameters of the plowing unit using noninversing plows PB-5, which are different from the known units with moldboard plows equipped with CibIME – LP-0,35 racks. The authors offer a plowing unit comprising a tractor of drawbar category 3 VT-100D and the new noninversing plow PB-5 for the technology of basic nonmoldboard cultivation in arid areas that ensures high productivity and reduction of energy consumption with equal performance quality, compared to serial plowing unit VT-100D+PLN-5-35+LP-0,35.En la Federación de Rusia, una gran cantidad de tierras de cultivo se encuentra en regiones áridas, que se caracterizan por un clima continental fuerte, fuertes vientos y lluvias insuficientes. En tales áreas, la tecnología del procesamiento básico de vertederos, como una forma de acumulación y conservación de la humedad en el suelo, se ha extendido. La especificidad de esta tecnología radica en el desmoronamiento continuo de la capa cultivable cultivada sin recambio de la formación con la máxima preservación de los rastrojos y restos de plantas en la superficie del día del campo. En zonas áridas, para el aflojamiento continuo de la capa cultivable, los implementos de labranza que no son de vertedera se han utilizado ampliamente: cortadores planos, desgarradores profundos y arados de arado compartido, en los que se instalan bastidores SibIME - LP-0.35 en lugar de cascos. Como resultado de la investigación, el problema de aumentar la eficiencia de la labranza principal del vertedero en campos ubicados en áreas áridas de la agricultura se resolvió mejorando los parámetros operativos y tecnológicos de la unidad cultivable con el arado cultivador PB-5, que difiere de la unidad conocida con un arado de cuchilla equipado con un soporte SibIME - LP-0.35. Los autores del artículo propusieron una unidad de cultivo que consiste en un tractor VT-100D de clase 3 y un nuevo desgarrador de arado PB-5 para la implementación de la tecnología de cultivo básico de labranza en condiciones de cultivo en seco, que proporciona una alta productividad laboral y menores costos de energía con indicadores de calidad equivalentes en comparación con una unidad en serie VT-100D + PLN-5-35 + LP-0.35.в Российской Федерации большое количество сельхозугодий расположено в засушливых районах, которые характеризуются резко континентальным климатом, сильными ветрами и недостаточным количеством атмосферных осадков. На таких территориях получила распространение технология основной безотвальной обработки, как способ накопления и сохранения влаги в почве. Специфика этой технологии заключается в сплошном крошении обрабатываемого пахотного слоя без оборота пласта с максимальным сохранением стерни и растительных остатков на дневной поверхности поля. В засушливых зонах для сплошного рыхления пахотного слоя стали широко применяться безотвальные почвообрабатывающие орудия: плоскорезы-глубокорыхлители и лемешно-отвальные плуги, на которые вместо корпусов устанавливаются стойки СибИМЭ – ЛП-0,35. В результате проведенных исследований решена проблема повышения эффективности основной безотвальной обработки почвы на полях, находящихся в засушливых районах земледелия, за счет улучшения эксплуатационно-технологических показателей пахотного агрегата с плугом-рыхлителем ПБ-5, отличающегося от известного агрегата с лемешно-отвальным плугом, оснащенным стойкой СибИМЭ - ЛП-0,35. Авторами статьи предложен пахотный агрегат в составе трактора тягового класса 3 ВТ-100Д и нового плуга-рыхлителя ПБ-5 для выполнения технологии основной безотвальной обработки почвы в условиях засушливого земледелия, обеспечивающего высокую производительность труда и снижение энергозатрат при равноценных показателях качества в сравнении с серийным агрегатом ВТ-100Д+ПЛН-5-35+ЛП-0,35

Results of experimental investigations of a flexible active harrow with loosening teeth

ArticleSoil tillage processes significantly affect the growth of cultivated plants; therefore, improvement of various designs and combinations of ploughs is still an actual practical and scientific task. This paper presents investigations of the design of a soil tillage machine consisting of three plough bodies equipped from the lateral side with a module with a flexible active harrow driven by a support wheel. The technological process of tillage by this machine is carried out in such a way that the module of the flexible active harrow is installed at a certain depth of soil tillage. The purpose of this work is an experimental comparative investigation of the quality indicators of the work of a design of the soil tillage working body with a flexible active harrow having loosening teeth. In the process of comparative experimental investigations of the operation of ploughs with a standard flexible harrow and an experimental active harrow having loosening teeth, the soil lumpiness (characterising the quality of crumbling) and water permeability of the obtained soil structure were estimated. An experimental model of this working tool was tested under the production conditions, and it showed advantages of loosening and crumpling the soil compared to the conventional harrows. This can be explained by the fact that the harrow tines, freely mounted on the axes of its links, ensure their oscillatory movements when moving in two different planes, thereby creating conditions for more intense soil disintegration