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The experimental setup for studying fibre orientation effects on air permeability of fibrous layers is described. The orientation parameter is obtained through small-angle scattering by laser radiation. Experimental dependence of pressure drop on air velocity follows Darcy's law. Permeability factors depend on orientation parameters and effective density of porous layers. It is demonstrated that for a fibrous layer porosity of ε > 0.9, the streams around individual fibres may be considered independent.

In such a case, the resulting force acting on the entire layer can be defined by force summation over individual fibre length. Resistance force acting on the unit segment of a fibre inclined at an angle to the flow direction is specified by the formula involving two empirical constants, which defines longitudinal and transversal resistance factors.

Integrating the procedure over all possible fiber directions that are defined by axially symmetric angular distribution density gives the resistance force acting on the entire layer of fiber and also pressure drop value. A comparison with obtained experimental data gives the values of transversal and longitudinal resistance factors. Their ratio, which approximately equals to 2, fits the findings of other publications

A new sensor has been developed which will enable engine pressure data to be available at a cost suitable for the average production vehicle. Unlike many previous devices this sensor will be suitable for the harsh environmental conditions of production vehicles themselves and not just the test environment. The sensor is small, extremely rugged and has a sufficiently wide bandwidth to be easily able to detect engine problems such as pre‐ignition, miss‐fire and malfunctioning engine components. Furthermore, the patented sensor technology does not require expensive electronic interfaces, but can use simple low‐cost off the shelf components. The sensor's performance and limitations are discussed, based on real data from a single cylinder petrol engine. An analysis of the sensor output signals, showing both time and frequency domain data under varying load conditions, is also included.

This paper aims to predict aerodynamic heating through the efficient solution of three‐dimensional viscous shock layer (VSL) equations, using axisymmetric analog.

The three‐dimensional VSL equations are written in the curvilinear streamline coordinate system. In these equations, normal momentum equation is replaced by Maslen's pressure relation. In addition to this, axisymmetric analog is implemented along the streamlines through assuming a zero value for circumferential velocity component. In this case, three‐dimensional VSL equations are reduced into an axisymmetric form, which can be solved much easier.

It is demonstrated that the solution of three‐dimensional VSL equations in the curvilinear streamline coordinate system, using axisymmetric analog, has made it possible to predict convective heat fluxes in both windward and leeward regions. Moreover, in comparison with the 3D VSL methods, the present approach dramatically reduces the CPU time of calculations. Comparison with the experimental and numerical data shows a good agreement between both of these data and the present results.

This method is an excellent tool for parametric study and preliminary design of hypersonic vehicles.

This method can predict convective heat flux in the leeward region where other similar methods are not applicable. In addition to this the present method is faster than other methods of solution for the 3D VSL equations.

A novel model of the upper arm under transcutaneous electrical stimulation with multi-pad electrodes is presented and experimentally validated. The model aims at simulating and analysing the effects of surface electrical stimulation on biceps brachii. The paper aims to discuss these issues.

Both the passive properties of tissues surrounding nerve bundles and the active characteristics of the nervous system are included. The output of the proposed model is nerve recruitment and muscle contraction.

Simulations and experimental tests on six healthy young adults have been conducted and results show that the proposed model gives information on electrically elicited muscle contraction in accordance with in-vivo tests and literature on motor unit recruitment order. Tests with different electrodes configurations show that the spatial distribution of active electrodes is a critical factor in electrically elicited muscle contractions, and that multi-pad electrodes can optimise the stimulation effectiveness and patient comfort with sequences of biphasic pulses of 350 μs at 30 pulses/s and threshold values of 2 mA.

Results encourage the use of the proposed model of the upper arm as a valid and viable solution for predicting the behaviour of the neuromuscular system when surface electrical stimulation is applied, thus optimising the design of neuroprosthetics.

To solve the problems caused by using precise molds for copper column positioning in the current column grid array package, this paper aims to optimize the proposed friction plunge micro-welding (FPMW) technology without mold assistance, to overcome the problems of low interfacial bonding strength, shrinkage cavities and flash defects caused by the low hold-tight force of solder on the copper column.

A pressurizing device installed under the drill chuck of the friction welding machine is designed, which is used to apply a static constraint to the solder ball obliquely downward to increase the hold-tight force of the peripheral solder on the copper column during welding and promote the friction metallurgical connection between them.

The results show that the application of static constraint during welding can increase the compactness of the solder near the friction interface and effectively inhibit occurrences of flash, shrinkage cavities and crystal defects such as vacancies. Therefore, compared with the unconstrained (UC) FPMW, the average strength of the statically constrained (SC) FPMW joints and aged SC-FPMW joints can be increased by 51.1% and 122.6%, and the problem of the excessive growth of the interfacial connection layer in the UC-FPMW joints during aging can be effectively avoided.

The application of static constraint effectively inhibits the occurrence of defects such as shrinkage cavities, vacancies and flash in FPMW joints, and the welding quality is significantly improved.

Long-run changes in living standards occupy an important place in development and growth economics, as well as in economic history. An extensive literature uses heights to study historical living standards. Most historical heights data, however, come from selected subpopulations such as volunteer soldiers, raising concerns about the role of selection bias in these results. Variations in sample mean heights can reflect selection rather than changes in population heights. A Roy-style model of the decision to join the military formalizes the selection problem. Simulations show that even modest differential rewards to the civilian sector produce a military heights sample that is significantly shorter than the cohort from which it is drawn. Monte Carlos show that diagnostics based on departure from the normal distribution have little power to detect selection. To detect height-related selection, we develop a simple, robust diagnostic based on differential selection by age at recruitment. A companion paper (H. Bodenhorn, T. Guinnane, and T. Mroz, 2017) uses this diagnostic to show that the selection problems affect important results in the historical heights literature.

This chapter sheds light on long-term trends in the level and structural dynamics of investments in Russian human capital formation from government, corporations, and households. It contributes to the literature discussing theoretical issues and empirical patterns of modernization, human development, as well as the transition from a centralized to a market economy. The empirical evidence is based on extensive utilization of the dataset introduced in Didenko, Földvári, and Van Leeuwen (2013). Our findings provide support for the view expressed in Gerschenkron (1962) that in late industrializers the government tended to substitute for the lack of capital and infrastructure by direct interventions. At least from the late nineteenth century the central government's and local authorities' budgets played the primary role. However, the role of nongovernment sources increased significantly since the mid-1950s, i.e., after the crucial breakthrough to an industrial society had been made. During the transition to a market economy in the 1990s and 2000s the level of government contributions decreased somewhat in education, and more significantly in research and development, but its share in overall financing expanded. In education corporate funds were largely replaced by those from households. In health care, Russia is characterized by an increasing share of out-of-pocket payments of households and slow development of organized forms of nonstate financing. These trends reinforce obstacles to Russia's future transition, as regards institutional change toward a more significant and sound role of the corporate sector in such branches as R&D, health care, and, to a lesser extent, education.

COVID-19 has shown its pandemic powers to the whole world. At times when many countries are forced to go for total lockdown of its economic activities, unusual economic crisis is inevitable. Amid all the crisis, the impact on education sector was also massive. In India also COVID-19 has resulted in a country-wide lockdown, which led to closure of schools and colleges. University Grant Commission, an apex educational body has come up with several guidelines for higher education institution. This study is an attempt to understand the perceptions of Indian tertiary students toward online teaching which has become the no-other-choice method of instruction for educational institutes during the pandemic. An online survey was conducted in October 2020, to collect information from the students through Google form about their perceptions and experiences with online learning. A total of 248 students completed the survey. Factor analysis has been applied on the collected data to understand the factors which most impacted the students. Results showed that “less effectiveness,” “stress and boredom” and “connectivity challenges” were among the major challenges faced by these students in their online learning experience. This study urges the need for an educational strategy to be set by policy makers to respond to the challenges encoutered during online learning.

This chapter considers scenarios for the development of the Russian economy in the medium term under the “new reality” conditions, with the latter implying a slowdown in China’s economic growth rate, lower commodity prices, rising geopolitical tensions, and the rapid development of digital technologies leading to the fourth scientific and technological revolution. The results of scenario calculations show that the implementation of the economic growth target scenario requires targeted efforts to increase human capital, increase investment in fixed assets and innovation, export diversification, and achieve perfection in the quality of political and economic institutions. Sustainable growth of 3% per year in the medium term is possible only with the restructuring of the economy; otherwise, even with favorable conditions in the commodity markets and higher efficiency of the existing economic system, it is impossible to achieve high rates of economic growth necessary to significantly improve the quality of life.