Passive Means Research Articles

Dissect or not to dissect? Easy solution

Throughout the recorded past (from Edwin Smith Surgical Papyrus) anatomy education did not experience dramatic changes. Practically until the last 5–10 years we were using only a text and a cadaver. Only did generation Z start to experience an intervention of AI and VR in our dissection rooms and lecture halls. Literature research exhibits convincing evidence of the positive impact of these new pedagogical tools on student’s success and overall performance (Freeman et al. 2014; Michael 2006). Some new methods of active learning, however, have been proven to be more effective than others. Lombardi et al. (2014) observed that students who used plastic models, rather than prosected specimens or virtual dissections, scored considerably higher on both initial and follow‐up exams despite student perceptions that the different forms of actual dissections were of more value. Fancovicova et al. (2014) observed that students who had admittance to multiple forms of active learning performed at a higher level than students who had access to only one form (including dissection). Herur et al. (2011) reported that students who utilized multiple forms of active learning had significantly higher levels of retention at 15 and 30 days after the class than those who learned by passive means.There is a perception that dissection continues to be recommended as the golden standard of anatomical education. Our presentation will present our experience of exploration of the possibilities to improve student’s success through the creation of a technologically advanced anatomy classroom that allows the learning anatomy of living human beings, not only cadavers. First‐time students are able to hold their own 3D printed organs during lab exercises. We can observe anatomical variations and their effects on living specimens in real time. At the same time, traditional cadaver dissections allow us to appreciate the complexity of the human body.

An Integrated Dynamic Fall Protection and Recovery System for Two-Wheeled Humanoids

Robots face the eventuality of falling. Unplanned events, external disturbances and technical failures may lead a robot to a condition where even an effective dynamic stabilization is not sufficient to maintain the equilibrium. Therefore, it is essential to equip robotic platforms with both active and passive fall protection means to minimize damages, and enable the recovery and restart without physical human intervention. This work introduces a method to design an integrated safety system for two-wheeled humanoids. As a case study, the method is applied to a robot and experimentally tested under several conditions corresponding to different causes of robot instability, such as motor jamming, external disturbances, and sudden shut-down.

A HOLISTIC APPROACH TO THE SPACE DEBRIS MITIGATION

The space activities in almost every orbital regime are now jeopardized by the continuous growth of the space debris populations. To prevent the proliferation of the space debris in Earth orbit it is necessary to tackle the problem from dierent perspectives, exploiting the latest theoretical and experimental knowledge in dierent elds, such as astrodynamics, spacecraft engineering and legal studies, to address four main pillars: prevention, protection, mitigation and regulation. In this respect the European Community nanced a large H2020 project named ReDSHIFT whose goal is to nd passive means to mitigate the proliferation of space debris. A short summary of the project and of its main ndings is given in the paper, with particular emphasis on the more theoretical part, related to the simulation of long term evolutionary scenarios of the whole space debris environment and to the mapping of the Low Earth Orbit phase space, looking for passive dynamical de-orbiting solutions.

Suppression of instabilities of swirled premixed flames with minimal secondary hydrogen injection

The impact of hydrogen addition on the dynamics of a methane-air premixed flame is explored for different injection strategies. The configuration is a swirled injector with a central tube for pilot fuel injection. Keeping the air flow rate and thermal power of the burner constant, it is shown that even for very small flow rates of hydrogen, as low as one percent of the thermal power, flame stabilization and combustor stability are greatly altered when pure hydrogen is injected through the central tube as a pilot jet. It is also shown that fully premixing the same quantity of hydrogen with methane or use of methane for the pilot jet has no significant effects compared to hydrogen pilot injection strategy. The flame response to forced flow perturbations is use to interpret the observed features. It is shown that hydrogen piloting drastically changes the gain of the flame transfer function at low frequencies and its phase lag at high frequencies, while other injection strategies barely change the flame response for these minute flowrates. CO and NOx emissions are finally examined for the different injection strategies. NOx emissions are found to drastically increase with hydrogen piloting compared to other injection strategies. These experiments indicate that pure hydrogen injected in minute fractions may be used as an efficient passive control means to mitigate combustion instabilities, but a compromise needs to be made with emissions.

Performance Enhancement of a Transonic Axial Flow Compressor with Circumferential Casing Grooves to Improve the Stall Margin

The stability range of the gas turbine engine compressors is being challenged in the modern days due to the intention of increasing per stage maximum loading. Casing treatment has been widely adopted as a realistic passive flow control means to improve the stall margin with a slight decrease of efficiency at the same time by various grooves of which shape (location, angles and so on) has a significant influence on controlling effect. However, the influence of some details in grooves is ignored in most of the case that may impact the specific flow field in the groove. A research on the impact of chamfer and fillet corners on the performance of casing treatment was proceeded by numerical simulation in this paper. The performance of different models of grooves on NASA Rotor 37 was investigated by discretizing 3D RANS based on finite volume method. Firstly, steady simulations were performed on NASA rotor 37 for validation. The CFD results and experimental data for adiabatic efficiency and pressure ratio were in good agreement. According to convergence criteria, the initiation of the stall was predicted. Few numbers of circumferential grooves casing treatment (CGCT) models have been proposed and tested numerically. Rectangular CGCT shape and smooth wall casing performances were analyzed. Moreover, the highest adiabatic efficiencies and stall margins of smooth wall casing, rectangular grooves and rectangular grooves with chamfer and fillet corners shapes models were compared to evaluate the influence of the shape of grooves on the stability and performance on axial flow compressor. The rectangular circumferential casing grooves and rectangular grooves with chamfer and fillet corners enhanced significantly stall margin and an operational range of the transonic axial flow compressor but adiabatic efficiency was slightly decreased.

Game changers in vascular and endovascular surgery

Game changers in vascular and endovascular surgery

Effect of passive protection on fire propagation of electrical cables

SummaryFlame retardant cable coatings are applied to grouped electrical cables as a passive protection means to reduce the fire hazard. This work studied the flammability of cable coatings and developed a fire test method to evaluate the fire propagation propensity of grouped cables protected by cable coatings. Firstly, ignition tests of 12 cable coatings were conducted and showed that all cable coatings are ignitable. Secondly, three selected cable coatings and a cable bandage, as an alternative passive protection method, were evaluated along with two types of electrical cables in ASTM E‐2058/ISO 12136 by measuring the fire propagation index (FPI). The FPI values of coated cables do not demonstrate a monotonous change relative to the FPI of uncoated cables, and the FPI trend is cable dependent. Thirdly, two selected cable coatings and a cable bandage were further examined in the 2.4‐m parallel panel fire test (PPT) along with an electrical cable with an FPI value of 30 (m/s1/2)/(kW/m)2/3. The cables coated by both tested cable coatings showed fire propagation while the bandaged cables did not propagate. The consistent fire propagation propensities between the PPT and small‐scale fire tests support using the FPA tests to examine the flammability of cable coatings.

Interface passivation and electron transport improvement via employing calcium fluoride for polymer solar cells

To enhance the performance of inverted structure polymer solar cells (PSCs), interfacial engineering considered as an effective and straightforward method was employed. In this study, to overcome the surface traps and energy level mismatches of the electron transport layer, a means of interface passivation by evaporating an ultrathin CaF2 layer above ZnO thin film as the electron transport layer was successfully adopted. We display that CaF2 layer could passivate the surface traps of ZnO thin film and decrease the interfacial barrier between PC61BM and ZnO, so that electron transfer efficiency is facilitated, the recombination of electrons and holes is inhibited at the contact interface, and the series resistance is reduced. After the introduction of the CaF2 layer, the short-circuit current and the fill factor was greatly improved, also the power conversion efficiency (PCE) was increased from 3.21% of the reference device without the CaF2 layer to 4.22% in the inverted PSCs based on P3HT:PC61BM bulk heterojunction photoactive layer. These results could have special guiding significance for high-efficiency PSCs and also great potential for applications of photovoltaic devices in the future.

The Practice of States on Air Defense Identification Zones: Geographical Scope, Object of Identification, and Identification Measures

Abstract This note provides a survey of the practice of States on ADIZs. It is found that while some ADIZs are entirely within territorial airspace, most extend beyond the outer limit into the airspace above the EEZs and even the high seas; and in the part beyond territorial airspace, transiting aircraft are prevalently subject to identification. Transiting military aircraft, which most of the time refuse to identify themselves voluntarily by submitting a flight plan or reporting their positions, may nevertheless be identified passively through radar detection, radio communication or close visual check. As most ADIZs are within the claiming State’s FIRs, transiting civil aircraft can be identified “unconsciously” through civil air traffic control. Where an ADIZ extends beyond the claiming State’s FIRs, most transiting civil aircraft comply with voluntary identification measures, presumably due to the light extra burden incurred. The non-compliant are easy to identify through passive means such as radar detection and radio communication, with the use of close visual check highly unnecessary.

Current state and prospects of development of passive radio engineering monitoring of storm activity

Passive radio engineering monitoring means of storm activity in VLF range are considered in the work. The comparative analysis of characteristics of modern Russian and foreign lightning location systems which have a broad practical application is carried out. Possibilities of improvement of precision and probabilistic characteristics of VLF methods and techniques for location of various types of lightning high current components are estimated.

Precision Medicine and Suicide: an Opportunity for Digital Health.

A better understanding of suicide phenomena is needed, and precision medicine is a promising approach toward this aim. In this manuscript, we review recent advances in the field, with particular focus on the role of digital health. Technological advances such as smartphone-based ecological momentary assessment and passive collection of information from sensors provide a detailed description of suicidal behavior and thoughts. Further, we review more traditional approaches in the field of genetics. We first highlight the need for precision medicine in suicidology. Then, in light of recent and promising research, we examine the role of smartphone-based information collection using explicit (active) and implicit (passive) means to construct a digital phenotype, which should be integrated with genetic and epigenetic data to develop tailored therapeutic and preventive approaches for suicide.

Сomprehensive provision of standard power quality parameters in three-phase networks by the use of hybrid filter-compensating converters

In this work the conditions of the most effective use of the developed perspective means for the solution of the actual problem of complex providing of electromagnetic compatibility in modern distribution public electricity networks are considered. This is achieved by improvement of a number of voltage quality characteristics (harmonics, asymmetry and voltage fluctuations). The simulation model of a three-phase four-wire distribution network is proposed, which allows estimating voltage quality characteristics when connecting non-linear and asymmetric loads. The simulation modeling of the operation of the specified network with certain characteristics, with different values of the power of single- and three-phase nonlinear load (rectifiers) is carried out. The simulation results showed that in modern conditions, with a high concentration of electronic equipment in the distribution network, it is not enough for each separate unit of equipment to have a built-in individual means for reducing the emission of disturbances, which ensures compliance with the requirements of the European Harmonized Standards for Electromagnetic Compatibility. Therefore, in order to solve this problem in the electricity networks it is suggested for consumers to additionally apply group electromagnetic compatibility means, including hybrid filter-compensating converters that combine functional capabilities of a regulated filter balancing device which based on an autotransformer with the zig-zag connection of windings and an active parallel power filter. The analysis of simulation results of a three-phase electric network with standard characteristics of a distribution transformer allowed to determine the ratio of power of one- and three-phase nonlinear load of consumers and linear load asymmetries in network, for which a hybrid filter-compensating converter has an advantage over the known passive group means of improving the quality of voltage and allows you to provide the quality of voltage in accordance with the norms of the international standards.

Overshoot elimination of the evaporator wall temperature of a loop heat pipe through a bypass line

During the startup period, a loop heat pipe (LHP) may experience a temperature overshoot, which often leads to a startup failure. As a passive means to alleviate the temperature overshoot in the evaporator, a bypass line was proposed that connects the evaporator vapor exit and the liquid reservoir, to facilitate quick escape of the vapor. The bypass line was incorporated into an LHP having a sintered metal wick and a flat evaporator, of which the dimensions were 40 mm × 50 mm. The wall and tubing system were made of stainless steel, and distilled water was used as the working fluid. An experiment was conducted to identify the effect of the bypass line on the LHP performance, in terms of the temperatures at the representative points and the thermal resistance. The characteristics were compared between the LHPs with and without the bypass line up to an input thermal load of 160 W. The experimental results for the LHP with the bypass line showed cases where the overshoot temperature was suppressed as much as 92.5°C, and the startup time was reduced by 5.2 min, without considerable sacrifice in thermal resistance.

Wall-mounted flexible plates in a two-dimensional channel trigger early flow instabilities.

A high level of mixing by passive means is a desirable feature in microchannels for various applications, and use of flexible obstacles (or plates) is one of the prime choices in that regard. To gain further insight, we carry out two-dimensional numerical simulations for flow past one or two flexible plates anchored to a channel's opposite walls using a fluid-structure interaction framework. For the inlet flow Reynolds number vs the Strouhal number plane, we observe a sudden flow change from a laminar to a time-periodic vortex shedding state when flexible plates are present in the channel. We found the critical Reynolds number to be Re_{cr}≈370 when a single plate is anchored on the channel wall and Re_{cr}≈290 or even lower when two plates are anchored. With an increase in the inlet flow Reynolds number (up to 3200), we found that vortices detach regularly at the plates' tips, which causes the flow to meander in the channel. In a two-plate anchored configuration, primary vortices generated at the first plate are constrained by the second plate and result in an energetic secondary vortex generation in the downstream side. The overall flow features and the energy dissipation in the channel are mainly controlled by the separation gap between the plates. At high-inlet-flow Reynolds numbers (≥1600), the probability density function (F) of the kinetic energy dissipation in a flexible plate configuration shows a stretched exponential shape in the form F(Z)∼1/sqrt[Z]e^{-pZ^{q}}, where Z is the normalized kinetic energy dissipation and the constants p=0.89 and q=0.86. The observed increase in energy dissipation comes at the cost of an increase in pressure loss in the channel, and we found that the loss is inversely related to the plates' separation gap. From our simulations, we found that if high mixing levels are desired, then two flexible plates anchored to the channel walls is a better choice than a channel flow without obstacles or flow past a single plate. The two-plate configuration with zero separation gap between the plates is best suited to achieve a high mixing level.

El mito como apertura al mundo. Sobre un equívoco en el pensamiento de Patočka

The task of my inquiry is to lay out the main tenets of Patocka’s analyses of the myth and to highlight the cardinal function these analyses possess in relation to the question of world. I show that Patocka’s interpretation of the myth is marked by a profound ambiguity: when the myth is contrasted with the free and “questioning” attitude of “historical humanity”, it is conceived as the vector of a passive and heteronomous meaning and the world thus revealed is fundamentally determined by the temporal dimension of the past. On the other hand, when it is opposed to the domineering knowledge stemming from the modern scientific project, the myth appears to gather and to extend the Urdoxa, our primal commitment to the world. On this view, the myth testifies for the autonomy of the world: the world cannot be captured in all its amplitude when it is seen as a mere reflection or correlate of a human project of meaning. The tension that emerges from these descriptions has its source in an equivocal, possessing a structuring function for Patoka’s thinking, as to the primal and paradigmatic meaning of the world and as to the type of human comportment most likely to capture it.

КОМПЛЕКСНЕ ЗАБЕЗПЕЧЕННЯ ВІЙСЬК ЗА ДОПОМОГОЮ АВТОМОБІЛЬНИХ ПЕРЕВЕЗЕНЬ

The provision of road transport is a complex of measures for enemy's intelligence, areas of loading (unloading) and traffic routes, protection against weapons of mass destruction and inflammation, protection, camouflage, anti-aircraft, anti-tank defense, engineering, material, technical and medical supplies. Protection against weapons of mass destruction includes: radiation, chemical and bacteriological exploration; warning of personnel about the threat of use by the enemy of weapons of mass destruction, information about the zone of damage, areas of debris and fires, alerts on radioactive, chemical and bacteriological damage; use of protective properties of the area and shelter; conducting anti-epidemic, sanitary and preventive measures; provision of means of antichemical protection, sanitary processing of personnel and special equipment processing; neutralizing the consequences of the use of weapons of mass destruction by the enemy. Protection of the automobile column is carried out continuously, mainly on its own resources and means, in accordance with the military calculation; the main attention being paid to organizing the alert of the personnel about the threat of an attack of the enemy and action on alert signals. In the organization of air defense car columns are used mainly by passive means of protection against air attack, namely: dispersed placement of units and their masking; vehicle and personnel shelter; increase of distances between cars when driving the column; use of natural conditions of the terrain. The purpose of material support is to provide motor vehicles with fuel and lubricants, and personnel - ammunition, means of protection, real estate and food products, as well as the creation of the necessary conditions for its heating during transportation in the cold season. Technical support for road transport includes the organization of maintenance, operation and repair of vehicles, as well as the evacuation of defective vehicles to repair sites. In the course of road transport, anti-epidemic measures should be envisaged, the main of which is the intelligence of the sanitary and epidemiological situation of transportation districts, and the carrying out of preventive disinfection measures.

Experimental Study on the Damping Effect of Multi-Unit Particle Dampers Applied to Bracket Structure

Particle damping (PD) is a passive mean of vibration control in which small metallic or ceramic particles are placed inside a cavity that attached to the primary structure at the place of high vibration amplitudes. The kinetic energy of the primary structure is dissipated by non-elastic impact and friction between particles and walls. This paper represents a series of experimental investigations of the effects of multi-unit particle dampers (MUPD) attached to a bracket structure under harmonic excitation and random excitation. As a platform to investigate the particle damping characteristics under extreme acceleration environments, the bracket structure was featured by an extremely high response on the top, and its maximum acceleration exceeds 50 times gravity acceleration when the bracket structure was subjected to resonance. This broad range of acceleration conditions was far beyond the scope concerned in most previous work. The experimental results show that for a small weight penalty (no more than 8.8%), multi-unit particle damper can reduce the resonance of the primary structure by more than 50%, whether under sinusoidal excitation or random excitation. And the response of the primary structure depends on the type of cavities and filled coefficient. Layering the cavity in the direction of the main vibration can improve the damping capacity of the multi-unit particle damper. And the damper with small particle size and large number of features is suitable for vibration reduction under high acceleration conditions.

Experimental Demonstration of Safety During Extended Station Blackout in an Integral Test Loop of a Natural Circulation Boiling Water Reactor

Decay heat removal for prolonged period of station blackout (SBO) is a safety concern of the nuclear reactors. Aftermath of Fukushima, safety evaluation (performance under severe conditions: stress test) of the reactors was carried out worldwide. It includes establishment of grace period of the reactors. Similar exercises for advanced heavy water reactor (AHWR) were also performed and the design of AHWR was established for its robustness against such events. Decay heat removal during extended SBO is such a condition to be qualified. In this regard, experiments in the integral test loop (ITL), a full scale test facility of AHWR, were conducted for continuous 7 days of extended SBO. Experiment was started with 6.8 MPa as the initial reactor pressure and decay heat removal was demonstrated for 7 days of SBO by passive means. It is observed that the pressure falls down to 1 MPa in 3 h. The design of AHWR was evaluated from safety critical aspects during such an event experimentally. During this event, the clad surface temperature was found to be well within safe limits of operations. As a result of this experiment, it can be concluded that the design of AHWR is capable to remove decay heat for 7 days of SBO with sufficient safety margins.

Indoor comfort and adaptation in low-income and middle-income residential buildings in a Nigerian city during a dry season

This paper investigates occupants' comfort, adaptation and their responses during the dry season in low-income to middle-income residential buildings in Abuja, Nigeria. The study aims to provide empirical data on occupants' comfort through evaluating 171 households in four different locations in Abuja. The study considered a combination of different research methods for data collection. Post-occupancy surveys were used to evaluate the buildings and residents' adaptation within the thermal environment. Thermal comfort surveys were also carried out in eight low-income residential households to assess occupants' perception of the thermal environment. Based on the short duration of the physical measurements, building simulation was also used to examine thermal comfort of occupants for an extended period. The Post Occupancy Evaluation (POE) results revealed over 70% of the occupants were dissatisfied with their thermal environment. The comfort surveys reported similar results with over 65% of the responses revealed being ‘uncomfortably warm’. The results showed an overall mean temperature of all the measured case studies to be 31.7 °C and the average temperature (predicted) of 30.7 °C. The neutral temperatures were in a range of 28°C–30.4 °C compared to the preferred temperature range of 27.5°C–29.4 °C. The prevalence of thermal discomfort highlights the need to explore the possibilities of reducing internal temperatures, particularly by passive means (fabric, shading, insulation etc.) given the need to avoid or reduce the need for air conditioning to make the buildings energy-efficient for low to middle income groups.

Исследование аэродинамических характеристик створки обтекателя ракеты-носителя с применением конических средств пассивной стабилизации

In the article, the aerodynamic characteristics of a detachable fairing door model are investigated with the use of passive stabilization means, which are conical bodies with flexible and rigid connections. Two types of experiments were conducted in a subsonic wind tunnel to determine the balancing angles of attack: a visualization experiment (using a video camera) and a measuring experiment (using the angle sensor). Mathematical flow models and aerodynamic quality values were obtained. The change in the balancing angle of attack and the corresponding aerodynamic quality of the studied combinations with respect to the base model were analyzed. Comparative characteristics of the considered stabilization variants were presented.