Propulsion System Considerations for the Subsonic V/STOL

1979 ◽  
Vol 101 (2) ◽  
pp. 228-232
Author(s):  
J. D. Cyrus ◽  
M. DeVillier ◽  
J. Kaminski

A representative subsonic V/STOL aircraft operating on a single mission has been used as a baseline to investigate the impact of various propulsion system tradeoffs. After establishing a cycle for the propulsion system and estimating V/STOL related installation penalties, parametric engine-aircraft-mission studies have been conducted. These studies have established takeoff gross weight benefits of up to 13 percent that may be obtained by appropriate selection of the core engine sizing location. Studies of two, three and four engine versions of the configuration have shown that three engine and four engine aircraft may have 20 percent lower weight than a two engine version, but this arises at the cost of significantly reduced hot section life.

Author(s):  
А.О. РЕНЗЯЕВ ◽  
О.П. РЕНЗЯЕВ ◽  
С.Н. КРАВЧЕНКО ◽  
Р.В. КРЮК

Исследованы прочностные и физико-механические свойства оболочки рапса с точки зрения ее разрушения и удаления. Установлено, что наиболее рациональным является двухстадийный способ обрушивания: 1-я стадия – на вальцовых мельницах, 2-я – на центробежной обрушивающей машине. Определены параметры центробежной обрушивающей машины для обеспечения минимальной необходимой линейной скорости 10,81 м/с: угол наклона отбойной пластины (90 ± 2)°, частота вращения барабана (2400 ± 150) об/мин. Установлено, что правильно подобранные условия и угол, под которым происходит удар, позволяют значительно снизить количество не до конца обрушенного семени и содержание расколотого ядра. При этом при свободном ударе об отбойную пластину под углом, отличным от 88–91°, или подаче недостаточно равномерного потока семян значительно увеличивается содержание необрушенных семян. На разрушение 1 кг семян необходимо затратить 58,45 Дж. Таким образом, по расчетным данным, для семян рапса диаметром 1,5 мм частота вращения барабана должна находиться в диапазоне от 2221 до 2565 об/мин при ударе семени под углом 90°. Диаметр семян рапса, выращиваемого в Сибирском регионе, составляет от 0,8 до 1,8 мм. Установлено, что подсушивание семян рапса в течение 30–40 с при температуре 100°С позволяет увеличить эффективность разрушения оболочки до полного ее отделения от ядра рапса. Представленные результаты позволяют повысить качество очистки семян рапса от оболочки и улучшить качественные характеристики получаемого масла, облегчить последующие технологические процессы получения пищевого масла, снизить затраты на рафинацию и дезодорацию на 2%. The strength and physico-mechanical properties of the shell of rapeseed in terms of its destruction and removal are investigated. It is established that the most rational is a two-stage method of seed hulling: the 1st stage – on roller mills, the 2nd – on a centrifugal hulling machine. The parameters of the centrifugal hulling machine to provide the minimum required linear speed of 10,81 m/s are defined: the angle of inclination of the turnback plate (90 ± 2)°, the rotational speed of drum (2400 ± 150) RPM. It is established that the correctly selected conditions and the angle at which the impact occurs, can significantly reduce the amount is not completely hulling seed and the substance of the split nucleus. At the same time, with a free impact on the turnback plate at an angle different from 88–91°, or the supply of an insufficiently uniform flow of seeds, the content is not completely hulling seed increases significantly. On hulling of 1 kg of seeds it is necessary to spend 58,45 J. Thus, according to the calculated data, for rape seeds with a diameter of 1,5 mm, the rotational speed of drum should be in the range from 2221 to 2565 RPM when the seed is struck at an angle of 90°. The diameter of rapeseed grown in the Siberian region ranges from 0,8 to 1,8 mm. It was found that drying of rapeseed for 30–40 s at a temperature of 100°C, can increase the efficiency of destruction of the shell to its complete separation from the core of rapeseed. The presented results make it possible to improve the quality of cleaning of rape seeds from the shell and improve the quality characteristics of the obtained oil, facilitate the subsequent technological processes of obtaining edible oil, reduce the cost of refining and deodorization by 2%.


2019 ◽  
Vol 14 ◽  
pp. 155892501985944
Author(s):  
Jitlada Boonlertsamut ◽  
Supaphorn Thumsorn ◽  
Toshikazu Umemura ◽  
Hiroyuki Hamada ◽  
Atsushi Sakuma

In this work, the spinning abilities of polyoxymethylene-based core–sheath bicomponent fibers were investigated. Bicomponent fibers were prepared using polyoxymethylene as the core material and poly(lactic acid) blended with polyoxymethylene or pure polyoxymethylene as sheath materials, and their characteristics were investigated and compared. Fiber properties such as elongation are important because they directly relate to the spinning performance during fiber processing. This work reports the impact of the composition designation of the core–sheath bicomponent fibers on the controllable stability of poly(lactic acid) in polyoxymethylene–poly(lactic acid) blends in the fibers, as well as the influence of the core–sheath material on the structure, fiber diameter and distribution, thermal stability, and mechanical properties of the core–sheath bicomponent fibers. It was found that the selection of core and sheath materials affected the structural characteristics of the fibers. The polyoxymethylene core–polyoxymethylene sheath (FV) fiber showed dimensional stability. However, the polyoxymethylene core–poly(lactic acid)/polyoxymethylene sheath (FT30) fiber provided the optimum limit of poly(lactic acid) content for controlling the stable properties of the core–sheath bicomponent fibers.


Genome ◽  
1993 ◽  
Vol 36 (1) ◽  
pp. 1-7 ◽  
Author(s):  
R. A. Morton

The impact of insecticide resistance is well documented. It includes the toxic effects of pesticides on the environment and the cost of the increased amounts of insecticides required to effectively control resistant insects. Resistance evolves by the selection of genes that confer tolerance to insecticides. Several resistance genes have been identified and cloned in Drosophila, including genes for mutant target molecules and genes that increase insecticide degradation. Drosophila is a useful system to understand the evolution of quantitative traits in general as well as the population genetics of insecticide resistance. Through it, we may hope to understand the relationship between discrete genetic change and continuously varying characters. In addition, molecular genetic techniques developed using Drosophila can eventually be transferred to other insects in order to help control pest populations.Key words: insecticide resistance, evolution of tolerance, selection of resistant genes, molecular genetics, Drosophila.


Author(s):  
T. T. Wong ◽  
Henry C.W. Lau

The nature of work is changing–to adapt to the global market. Many enterprises will concentrate on core activities and outsource other services to those with specialist expertise. Outsourcing is one way in which the pool of available knowledge can be enlarged and enhanced. Virtual enterprises are likely to rely on such knowledge to meet customers’ demands on a customer-built or small batch production basis. Although information technology plays an important role in linking the core company with its partner companies, it remains subservient to the humans that form the virtual enterprise. For effective knowledge management, it is clear that the electronic handshake would need to be based on trust between partner companies as well as the correct protocol. However, current practice showed that trust between top management teams was rarely considered in the selection of partner companies. A review of the relevant literature indicated that neither scholars nor practitioners agree on a single model of inter-firm trust that applies to all partner evaluation contexts. Hence a decision support system based on neural network and data mining technologies is proposed. A case example is used to illustrate the feasibility of incorporating inter-firm trust in real industrial situations.


Author(s):  
Borys Lukasik ◽  
Witold Wisniowski

The main goal of this paper is to investigate feasibility of using all-electric propulsion system for a mid-light business jet aircraft in the near future (20–30 years from now). The secondary goal is to assess the impact of using such system on operating costs and emission reduction. This paper presents calculations of business jet aircraft mission energy demands and compares them with batteries capabilities. Three different types of lithium batteries are investigated in terms of their energy densities projected for three different time frames. Mass of batteries that is required to provide demanded amount of energy to perform the mission is compared with the maximum mass of fuel that the baseline aircraft is able to take. On this basis, the feasibility of all-electric propulsion system is assessed. Additionally, in order to show the limitations of such system, maximum range is calculated for the mass of batteries that would potentially enable to perform the flight. Furthermore, CO2 and NOx emission of the baseline aircraft engines are compared with the amount of gaseous pollutants which are emitted by the power plant, when energy needed to recharge batteries is being produced. Finally, the potential fuel cost reduction is calculated based on the cost of electricity that would be used to recharge batteries.


2021 ◽  
Author(s):  
Roberto Company ◽  
Sabrina Hocine ◽  
Baptiste Pousset ◽  
Mikel Morvan

Abstract Brine composition is one of the key parameters in the design of a surfactant based oil recovery process and is a condition imposed by the reservoir nature. This brine can contain a large variety of ions including monovalent and divalent cations (hardness), which impacts the surfactants solubility. Moreover, hardness evolution during the injection process can also impair surfactant formulations’ performances. Water treatment processes are useful ways to mitigate such risks, but they imply higher CAPEX for the process. As a consequence, the selection of the right surfactant will have a large impact on the cost and on crude oil production. This paper describes solution properties of the most common surfactants used in surfactant flooding i.e. Alkyl Benzene Sulfonates (ABS) and Internal Olefin Sulfonates (IOS) as a function of the brine hardness and will be compared with Internal Ketone Sulfonates (IKS), a new bio-based surfactant family.


2019 ◽  
Vol 10 (4) ◽  
pp. 38-59
Author(s):  
Sarala Ramkumar ◽  
Zayaraz Godandapani ◽  
Vijayalakshmi Vivekanandan

In the modern world, globalization has made way for easy access to information systems for running businesses effectively. The misuse of information systems may lead to loss of productivity, revenue, and sometimes to legal liabilities. Therefore, information security is a major concern for running the business successfully. It is the responsibility of the information security personnel of an organization to develop strategies, and identify the suitable controls to mitigate the risks to which the organization is exposed to. Selection of a suitable set of security controls depends upon, the risks to be addressed, the impact of the risks in terms of revenue, and the cost incurred in implementing the selected controls. To assist in the selection of optimal security controls a hybrid intelligent approach combining the tabu search technique and genetic algorithm has been proposed. The obtained results prove that the proposed approach provides better results in the selection of optimal counter measures.


Author(s):  
Syed Hassan Raza ◽  
Rameez Khalid ◽  
Muhammad Wasif

In this research, generic and specific risks related to the critical activities of the engineering projects are identified. The surveys and interviews from various project managers and engineers of the leading consultant firms conducting engineering projects in Pakistan are the core identifiers. Specific risks associated with the common engineering projects are qualitatively analyzed to prioritize the risks according to their impact on the schedule and cost of the project. Critical activities related to the specific risks are identified. Estimated man-hours without and with quantitative risk assessment have been determined to study the impact of including risk analysis on the schedule and cost of the engineering projects. The relationship between the critical activities and the total man-hours have also been developed to identify the most critical activity or activities influencing the man-hours and ultimately the cost of the project. The likelihood of occurrence of risks are also related to the man-hour completion, to analyze the effect of certainty of the man-hour’s determination, which is an important aspect of estimating schedule, EMV and finally cost. Using the analysis, it has been inferred that the 95% confidence level is not suitable all the time for the estimation of risk impact on the schedule and cost. It increases the man-hour estimation resulting in less competitive proposal to win the project.


Publications ◽  
2021 ◽  
Vol 9 (3) ◽  
pp. 37
Author(s):  
Carmen López-Vergara ◽  
Pilar Flores Asenjo ◽  
Alfonso Rosa-García

Public research policies have been promoting open-access publication in recent years as an adequate model for the dissemination of scientific knowledge. However, depending on the disciplines, its use is very diverse. This study explores the determinants of open-access publication among academic researchers of economics and business, as well as their assessment of different economic measures focused on publication stimulus. To do so, a survey of Spanish business and economics researchers was conducted. They reported an average of 19% of their publications in open-access journals, hybrids or fully Gold Route open access. Almost 80% of the researchers foresee a future increase in the volume of open-access publications. When determining where to publish their research results, the main criterion for the selection of a scientific journal is the impact factor. Regarding open access, the most valued aspect is the visibility and dissemination it provides. Although the cost of publication is not the most relevant criterion in the choice of a journal, three out of four researchers consider that a reduction in fees and an increase in funding are measures that would boost the open-access model.


Author(s):  
Shafeeque Ahmed Kalavai ◽  
Prabhakar Karthikeyan Shanmugam

<p>Cost allocation of highly non-linear transmission loss is complex and essential in competitive electricity market. In most of the existing transmission loss/cost allocation approaches, real power loss depends on selection of slack bus and hence the cost of transmission losses which are allocated to the generators and the loads also varies. In this paper, a complete analysis on the impact of slack bus selection on transmission loss allocation with and without mathematical loss is made. One of the existing approaches, proportional generation and proportional load (PGPL) method is taken to illustrate the impact. Mathematical loss is the loss without generation and load in the network and can be obtained from power flow solution by taking generation and load as zero. The cost incurred for this mathematical loss is allocated to the transmission lines while the cost of transmission loss due to bilateral contracts is allocated among the sources and the consumers. These loss/cost allocations with and without considering mathematical loss is shown using an IEEE 30 bus, 57 bus, 75 bus and 118 bus systems. The simulation results are obtained using MATLAB R2014a.<em></em></p>


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