Equal Distance Research Articles

Multi-point in situ measurements of turbulent flow in a wind turbine wake and inflow with a fleet of uncrewed aerial systems

Abstract. The demand on wind energy for power generation will increase significantly in the next decade due to the transformation towards renewable energy production. In order to optimize the power generation of a wind farm, it is crucial to understand the flow in the wind turbine wake. The flow in the near wake close to downstream of the wind turbine (WT) is complex and highly three-dimensional. In the present study, for the first time, the SWUF-3D (Simultaneous Wind measurement with Unmanned Flight Systems in 3D) fleet of multirotor UASs (uncrewed aerial systems) is deployed for field measurements on an operating 2 MW WT in complex terrain. The UAS fleet has the potential to fill the meteorological gap of observations in the near wake with high-temporal- and high-spatial-resolution wind vector measurements plus temperature, humidity and pressure. During the experiment, the flow up- and downstream of the WT is measured simultaneously. Various flight patterns are used to investigate the near wake of the WT. The velocity deficit and the turbulence profile at different downstream distances are measured by distributed UASs which are aligned perpendicular to the flow in the near wake. The results show the expected double-Gaussian shape in the near wake under nearly stable atmospheric conditions. However, measurements in unstable atmospheric conditions with high turbulence intensity levels lead to single-Gaussian-like profiles at equal downstream distances (<1 D). Additionally, horizontal momentum fluxes and turbulence spectra are analyzed. The turbulence spectra of the wind measurement at the edge of the wake could reveal that tip vortices can be observed with the UASs.

Eğitim Kurumu Yöneticilerinin Kayırmacı Tutum ve Davranışlarının Sonuçları

In this study, where the results of nepotistic attitudes and behaviors of educational institution managers are examined, it is aimed to provide qualitative content support to researchers who will conduct research on this topic by contributing to the literature on the consequences of nepotism. The expectation of individuals in the business environment is based on equality, justice and receiving the response, behavior and appreciation that they deserve. Education managers should be equidistant from each employee at this point. They should evaluate teachers not according to kinship, gender or their closeness to people, but according to the quality of the work done. If there is favoritism in the educational institution, it can be clearly seen that education managers exhibit nepotistic attitudes. Education administrators, even if they are in an unfair situation, have a nepotistic attitude when they protect and protect the people they feel close to. There are also relations of interest in educational institutions where there is nepotism. As is traditionally the case in many cultures, nepotistic behaviors are often observed in our culture. Because in our society, relationships come before merit. Education managers often exhibit nepotism behaviors in issues such as fair distribution of workload and performance evaluation. For this reason, according to the level of empathy of teachers, whether educational administrators are fair in their nepotistic attitudes and behaviors can be understood from the trust felt in educational administrators and their constructive, analytical approaches in the field of education. Educational administrators working in educational institutions should manage their affairs by taking into account the principles of fairness and openness. Thus, education managers will have drawn a picture away from nepotism by keeping an equal distance from their colleagues. As a result of nepotism practices, the human resource, which is the most important element of the organization, cannot be managed in the desired way and this situation negatively affects the performance, which is the organizational product of the educational institution. While the private sector is affected to a limited extent, this impact is felt more intensely in the public sector, which costs the entire society. It has been determined that due to the nepotistic attitude applied by education managers, the absenteeism rates of educational institution employees have increased, their desire to quit their jobs has increased, and as a result of these attitudes, a working area has been formed in which the trust institution Decays, where a distinction is formed between employees close to or far from management. The expression of nepotism appears as an important problem that causes inequality from a social point of view and deeply affects society. As a result of the loss of social balance, an environment of chaos occurs in society, but there may be consequences that reduce the trust of citizens in public institutions and organizations. Trust in other public institutions and organizations, especially educational institutions, is disappearing, the anxiety level of educational staff and public employees, hence their desire to quit their jobs, is getting stronger, and corporate interest and loyalty are weakening. Key Words: Educational Institution, Educational Administrator, Nepotism

Investigation of the influence of dry extracts of bupleurum aureum and Salsola collina L. on the antimicrobial effect of co-trimoxazole

Scientific data on the pharmacodynamics of dry extracts of Bupleurum aureum and Salsola collina L. based on the results of studying the antimicrobial effect and the similar effect of co-trimoxazole when they are used together have been supplemented. The investigated phytoextracts do not show antimicrobial properties, but they do not change the antimicrobial effect of co-trimoxazole when they are used in combination.
 The aim of the study was to experimentally investigate the antimicrobial effect of extracts of Bupleurum aureum and Salsola collina L. and establish the possible antagonistic effect of these extracts on the antimicrobial drug co-trimoxazole when used together.
 Materials and methods. The research was conducted in May 2016. Screening of the antimicrobial effect of extracts of Bupleurum aureum and Salsola collina L. and establishing of the possible antagonistic effect of these extracts on the antimicrobial drug co-trimoxazole when they are used together was carried out in the laboratory of the Department of Microbiology of the National Pharmaceutical University, which has a certificate of attestation 045/14 dated 28.10.2014. For determination of antimicrobial activity, the agar diffusion method ("well" method), which is based on the ability of medicinal substances to penetrate the agar layer, was used. A set of reference strains of microorganisms was used: S. aureus ATCC 6538, E. coli ATCC 8739, P. aeruginosa ATCC 9027, B. subtilis ATCC 6633, C. albicans ATCC 10231. Petri dishes were filled with two layers of solid nutrient medium. The lower layer - 10 ml of melted "cold" AGV agar (medium No. 3), the upper layer - nutrient medium for the corresponding test strain. After cooling the lower layer of agar, three thin-walled steel cylinders (inner diameter - 6.0±0.1 mm, height - 10.0±0.1 mm) were placed on it at an equal distance from each other and from the edge of the cup. The top layer was poured around the cylinders - 13.5 ml of agar, melted and cooled to 45-48°С, mixed with the seed dose of the test microorganism (1.5 ml of microbial suspension, the concentration corresponding to the type of microorganism). After cooling the upper layer of agar, the cylinders were removed with sterile tweezers and 0.25-0.3 ml of the studied drug was added to the resulting wells. The results were recorded after 24 h by measuring the zone of growth inhibition, including the diameter of the wells. Measurements were made with an accuracy of 1 mm, while focusing on the complete absence of visible growth.
 The obtained data were analyzed using the methods of variational statistics. The significance level is p<0.05. The studied plant extracts of Bupleurum aureum (aqueous and alcoholic) and Salsola collina L. (aqueous and alcoholic) were used in doses of 0.005 mg/ml and 0.01 mg/ml, which corresponded to doses of 5 mg/kg and 10 mg/kg. Experimental data were also processed by parametric (Newman-Keuls) and non-parametric (Mann-Whitney) methods of variational statistics, using the Statistica 6.0 statistical software package; differences were considered statistically significant at p<0.05.
 Results. At the final stage, the determination of the antimicrobial effect of water and alcohol extracts of Bupleurum aureum and Salsola collina L. at doses of 1 mg/ml and 5 mg/ml was carried out, and the effect of BAS of these extracts on the antimicrobial effect of co-trimoxazole when used together was determined. In the course of the study, it has been established, that the addition of the above-mentioned extracts to the co-trimoxazole formulation does not affect its initial antimicrobial properties.
 Conclusion. Today, drug-induced liver injury remains one of the most important problems of hepatology and pediatrics, pharmacological science pays a lot of attention to the search for new effective and harmless drugs with a hepatoprotective effect, and the improvement of existing drugs is primarily aimed at increasing their specificity and reducing side effects related to the pharmacological properties of the drug. Currently, there is increasing interest in medicinal plants as a source of various biologically active substances (BAS), which provide a wide spectrum of pharmacological action of the agent, which allows to immediately affect various links of the pathogenesis of liver diseases. The analysis of scientific sources made it possible to establish that medicinal products of plant origin, thanks to BAS, possess polymodality of effects and reveal a versatile complex effect on the course of pathological processes in the body. Most drugs are characterized by good tolerability, absence of withdrawal syndrome and toxicity to parenchymal organs. Medicinal plants are used not only as monopreparations, but also in combination with synthetic drugs and as raw materials for obtaining BAS

Market Integration of Wholesale Chilli Prices of Pakistan

Vegetables hold very important and significant place in our diet, among vegetables chilli (Capsicum annuum L.) is one of the most important vegetable crop of Pakistan. The vegetable’s market integration is the major problem in Pakistan and symbol of efficiency is integrated markets. The present study was conducted for domestic integration of four major chilli markets of Pakistan by using their monthly wholesale chilli prices of eighteen years (June 2000 to July 2019) by adopting Johan-sane integration approach. The Augmented Dickey Fuller (ADF) test revealed that prices are integrated at first difference and results of pair wise integration showed chilli markets of Pakistan (Hyderabad, Lahore and Quetta) are integrated in the long-run and in short run with strong relationship, except Peshawar market because of long distance, price variation & seasonal effects. The results of Vector Error Correction Model (VECM) showed significant adjustment of prices in almost three pairs of markets (Hyderabad, Lahore and Quetta) and the finding of Granger causality test showed the bidirectional and unidirectional causality relationship between the chilli markets. Granger causality tests have also indicated that unlike in other market pairs such as Lahore-Peshawar and Quetta-Peshawar have no causality direction on price formation between them. The government should design a network of chilli wholesale markets across the country that are nearly equal distance apart in order to improve market convergence and price transmission to make chilli more profitable.

NOON-state generation and superresolved interference in a double-slit experiment

Maximally entangled NOON states are proposed to be generated with $N$ independent photons and a fixed double-slit in the Young's interference experiment. A strict condition is required that these photons have to be arranged in a straight line and separated from each other by certain equal distances. The initial product state turns into a NOON state of the photons at the double-slit, after $N$-photon postselected measurements. With a spatially random laser beam, we experimentally investigate the high-order correlation functions to imitate the behavior of the single-photon and $N$-photon wave packets of the NOON states. Since the $N$-photon wave packet is the product of $N$ single-photon wave packets, two methods are adopted to observe the superresolved fringes. The first method is to use the product of the second-order correlation functions. The second one is to measure the $2N\mathrm{th}$-order correlation functions. In the both cases, the superresolved fringes of up to fourth order are successfully observed.

Quadrant Multiplexing-based Geometrically Shaped Four-Dimensional Modulation Format for Polarization Multiplexed Coherent Optical Communication System

We present in detail the recently proposed novel geometric shaping four-dimensional (GS-4D) modulation format based on quadrant multiplexing and evaluate the signal from various aspects. GS-4D achieves a generalized mutual information (GMI) gain of 1.6 bits/4D-sym compared to polarization-multiplexed 16-ary quadrature amplitude modulation (PM-16QAM) at low signal-to-noise ratio (SNR) regions. Set partitioning (SP) at the expense of one bit of spectral efficiency is proposed to exponentially reduce the amount of constellation points and increase the Euclidean distance. For fiber channels influenced by additive white Gaussian noise (AWGN) and phase noise, a further GS scheme with binary labeling is designed. The scheme takes bit error ratio (BER) as fitness, preserves the feature of this format while using mirror symmetry to reduce the complexity, and is implemented by an improved particle swarm optimization (PSO) algorithm. Results demonstrate that the proposed scheme has high optical SNR tolerance and low BER performance. Compared with the PM-16QAM, the GS-4D, GS-4D with SP and GS-4D with SP-PSO can provide 3.6 dB, 5.6 dB and 6.6 dB optical SNR gain, respectively. With the equal distance of transmission, the BER of GS-4D is decreased by around one order of magnitude compared with PM-16QAM, the BER of GS-4D with SP is lowered by around two orders of magnitude, and the BER of GS-4D with SP-PSO is reduced by around three orders of magnitude.

INVESTIGATION OF THE SEALING UNIT OF THE ANNULAR PREVENTER

In this article, different kinds of sealing aspects for something like an annular тpreventer are looked at. It was looked at how spherical and cone-shaped sealing elements are made. The advancement of spherical seals has been looked into based on what other countries were doing. The sealing parts that are presently used for spherical circumferential preventers aren't really universal and only work with a small number of drill pipes. They also can't completely seal the well mouth when there are no drilling tools in the well. A seal for a annular-type preventer is considered. The sealer includes a large number of metal inserts embedded in the elastomeric body. The inserts are arranged radially at equal distances from each other around the longitudinal axis of the seal. They support the elastomeric body under radial compression, which ensures the sealing of the annular space. When the sealing assembly is compressed around the drill pipe, the elastomeric body is compressed radially in the direction of the longitudinal axis. Metal inserts move in the same direction. The disadvantage of this design is that in the closed position, the pressure in the borehole can affect the elastomeric body, which leads to a change in its stress state. As a result, significant stresses develop in certain areas of the elastomeric body, acting on the sealing assembly in two directions: radially to the center and along the longitudinal axis upwards. At significant pressures of the reservoir fluid, stresses can lead to the destruction of the seal. An annular sealing element placed between the lid and the plunger of a spherical annular preventer has been studied. The element is installed in the spherical cavity of the lid and consists of an elastic material reinforced with rigid inserts. This design has a disadvantage associated with the wear of the working surfaces. When the tool is axially moved through a closed sealing element, a narrow belt of elastic material near the inner upper edge of the sealing element first wears out. Then, as it wears out, the width of the belt increases, reaching full height at the end. Keywords: circular sealing element, cylindrical sealing element, strengthened metal inserts, elastomeric body, annular preventer.

Pneumatic and acoustic suit: multimodal haptic suit for enhanced virtual reality simulation

A haptic device provides users with physical feedback to enhance their experience in virtual reality (VR). We developed a multimodal haptic suit, called as Pneumatic and Acoustic (PA) suit, which exhibits high-resolution haptic feedback, and applies high pressure and realistic vibration to a user. The PA suit artificially simulates the sensation of brief and strong collisions such as the impact of an explosion, ball, or fist. The pneumatic actuators, consisting of 40 air bladders, are designed as bellows-type pneumatic devices for vertical inflation. The air bladders are placed on the chest at an equal interval distance of 30 mm for high-resolution feedback. The acoustic actuators use an effective sound signal of a collision similar to realistic vibrations. This study aims to examine the effectiveness of our multimodal haptic suit in improving VR experience of users. The recognition tests clearly show that participants distinguish between the haptic patterns and position of collided virtual objects with the suit. The user study involving a collision of a ball shows that the PA suit transmits the approximate pressure of a real ball collision with artificial haptic feedback. Our receiving ball and explosion VR simulations confirm that the PA suit improves a VR experience depending on the types of actuators and VR contents. The results prove that the PA suit creates distinguishable haptic patterns for guiding a task and improves the VR experience of users with powerful and multimodal haptic feedback hence providing high-quality VR simulation.

Surface modification of alloys by high-energy pulsed particle beams

The effect of particle beams on the surface of alloys is often used to obtain a material with desired characteristics. Mathematical modeling of such surface modification leads to the study of diffusion in the presence of an intense external source of diffusant. In this case peculiarities in material structure may be of great importance. A special role belongs to inter-grain boundaries in metals, the vicinities of which are regions of accelerated diffusion. Moreover, if the surface treatment by particle beam is carried out with short impulses comparable with relaxation times of diffusion and chemical processes to their equilibrium course, it may be necessary to explicitly consider the particle transfer rate in the material, for example, using the non-classical laws.In this paper we discuss the model of the treatment process by particle beam, which takes into account both the feature of grain boundary diffusion and finiteness of relaxation times of diffusion fluxes in the boundaries and in the volumes of grains. The problem is considered in two-dimensional formulation. The grains and their boundaries are treated as separate phases with different diffusion properties. The grains are represented in the form of rectangles, located at equal distances from each other. The relative size of the boundary phase may vary. Using generalized equations for diffusion fluxes with finite time of relaxation, we come to diffusion equations of hyperbolic type for the volume and the grain-boundary phases. It is assumed that between the diffusant and the treated material a summary chemical reaction occurs with formation of a summary product. A numerical study allowed us for the first time to establish the features of grain-boundary diffusion and to study the dynamics of reaction product formation for treatment times comparable to relaxation times. The effect of pulse duration and grain size on the diffusant concentration distribution for these conditions was investigated.

Assessment of Locomotive Receivers’ Sensitivity Using Test Loop with Crossing

Main technical and operational characteristics of the locomotive receiver of the automatic locomotive signalling system, which is part of all types of core locomotive safety devices, comprise its sensitivity. This characteristic makes it possible to estimate by indirect methods the signal/noise ratio at the input of the locomotive receiver, and, therefore, to evaluate the noise immunity of its operation at the nominal parameters of amperage and current frequency of signals of automatic locomotive signalling system in the track circuit under operating conditions.Thanks to correct adjustment of the sensitivity of the locomotive receiver, it is possible to significantly reduce the number of failures in operation of the main locomotive safety devices. Checking the sensitivity of the locomotive receiver and other parameters of safety devices is carried out at control points, usually equipped in depots, using stationary test loops that simulate the electromagnetic field generated by the signal current flowing in the track circuit. Sensitivity measurement results are influenced by various factors, primarily the position of the receiving coils along the test loop performed with crossings, as well as the distance between adjacent crossings. The influence of these factors may lead to the impossibility of checking the correct operation of locomotive safety devices at nominal signal parameters, as well as to an incorrect assessment of sensitivity.The objective of this work is to evaluate the influence of these factors on the results of measuring the sensitivity of a locomotive receiver. A model developed as part of the work and based on the well-known methods of analysis and synthesis and the Biot−Savart− Laplace law describes the inductive connection «test loop−coil». Several characteristic dependencies have been also obtained. The results have been compared with the existing requirements for the position of the coils relative to the test loop performed with crossings.To ensure the most accurate results of measurements of the sensitivity of the locomotive receiver, it is proposed to place the receiving coils of the locomotive safety devices at an equal distance from adjacent crossings of the test loop.

«Загадка» о центре V части Кантаты op. 31 Антона Веберна

The article presents an analytical commentary of Anton Webern’s elucidation of the form in Freundselig ist das Wort (the fifth movement of his Cantata opus 31): “In the centre are the words: 'Weil er am Kreuz verstummte <...>” (from a letter to Hildegard Jone dated 25 July, 1942). Although the boundaries of the phrase about the Cross are clearly marked by double barlines in the musical score, it is not easy to understand exactly what Webern meant. Kathryn Bailey, the author of an article about the Cantata Opus 31 and a book about Webern's serial works, has labeled his statement about the centre as “somewhat imprecise to say the least” and the bars encompassing it “a riddle.” Responding to these evaluations and drawing on Bailey’s research — primarily, the signs of the central symmetry in the serial canon Freundselig ist das Wort demonstrated by her — the author of this article offers her own version of the solution to the question of the centre. An analysis from the position of metrotectonicism shows that, first, the phrase about the Cross does not present the centre in a strict sense, although it is located at the centre of the five sections of Freundselig ist das Wort, and, second, that a compositional centre does, indeed, exist here. This is demonstrated by the peculiarly shaped ending to the phrase about the Cross, which corresponds to the notion of a “central cadence,” which, according to Georgy Konyus, is “a sort of knot binding the identical or similar constructions placed on either side of it,” and is situated at an equal distance from the beginning and final points of the form.

Examination of Systematic Errors of a Roundness Measurement Equipment

The profile in the frontal section of a solid of revolution forms a perfect circle if all of its points are at an equal distance from the center line. The value of the deviation from circularity is very important and it is measured with a dedicated measuring device. This paper examines the systematic errors in a measuring device in which the measured workpiece is supported and rotated between two live centers, while a dial indicator detects the deviations. Regarding the structure, this paper proposes a model consisting of five systematic error measurements which considers the eccentricity of the live centers and the tilt of the dial indicator axis.

Effect of Nutlin-3a on stability of p53-MDM2 complex

<sec>P53 is well recognized to be a tumor suppressor protein. In response to the external stress or environmental perturbation, p53 can promote the transcription of various target genes downstream, thus regulating the cell cycle, apoptosis, DNA repair, and angiogenesis. However, the activation of p53 is further activated by another protein, MDM2, which negatively regulates the level of p53 inverse and thus reduces the activation of p53. This phenomenon is a novel potential and promising strategy for cancer therapy, i.e. restoring the activity of p53 pathway through the competitive inhibitors that can occupy the p53-binding site of MDM2 and thus inhibit the interaction between p53 and MDM2.</sec><sec>Recently, various kinds of the inhibitors have been designed for this purpose. The Nutlin family is a group of well investigated inhibitors, which shows high efficiency for tumor suppression. Nutlin-3a mimics the MDM2-binding site of p53 essentially, and blocks the binding of MDM2 to p53. Once getting free from MDM2, p53 rapidly accumulates in the nuclei of cancer cells, the p53 target genes and the p53 pathway are activated, thereby resulting in cell-cycle arrest and apoptosis. In our previous papers, we investigated the competition mechanism between Nutlin3 and p53 <i>in vitro</i> by using molecular dynamics simulations. We found that Nutlin3 can bind faster than p53 to prevent p53 from binding to MDM2 when Nutlin-3a and p53 have equal distance from MDM2. Nutlin-3a can also bind to the p53-MDM2 complex to disturb and weaken the interactions between p53 and MDM2. However, the underlying mechanisms of p53-MDM2 complex instability <i>in vivo</i> are still unclear. And these inhibitors also have a variety of specificities and biological toxicities <i>in vivo</i> environment.</sec><sec>In this study, we go a further step to investigate the effect of Nutlin-3a on the stability of p53-MDM2 complex in physiological environment with the aid of the molecular mechanics/generalized borne surface area (MM/GBSA) method. In our simulations, a group of Nutlin-3a molecules are randomly put around the p53 binding pocket of MDM2 in the initial stages to examine the dynamics among p53, MDM2 and the group of Nutlin-3a molecules and to analyze the underlying competition mechanism between Nutlin3 and p53 binding to pocket of MDM2.</sec><sec>We find that Nutlin-3a can induce the centroid distance between p53 and MDM2 to increase. Importantly, we show that Nutlin-3a weakens the binding affinity of p53-MDM2 complex. Consistently, Nutlin-3a breaks a hydrogen bond between Phe19-Gln72 and a salt bridge between Glu17-Lys94, which weakens the interactions between p53 and MDM2. From the systematic biology point of view, the regulation of p53 by MDM2 is extremely sensitive to the strength of the p53-MDM2 interaction. The avianization of the interactions between p53 and MDM2 by Nutlin-3a can promote p53 to restore its suppression functions on tumor development.</sec><sec>This study may be helpful in understanding the molecular mechanisms of p53-MDM2 complex instability mediated by Nutlin-3a and also in searching for the effective inhibitors of p53-MDM2 interaction.</sec>

Choice of a logistics route for cargo delivery in modern conditions

The current conditions of the global movement of goods under sanctions make it necessary to build new logistics routes along those international transport corridors that will ensure the reliability of transportation. Crisis points in any industry are at the same time a potential for development and growth, which is confirmed by the history of the development of logistics in the XX century. Basic principles of logistics and methods of quality management theory should serve as a basis for choosing the vector of transport and production development. Transit potential of the Russian Federation is unlocked by the Northern Sea Route, latitudinal corridor “East-West” and meridional corridor “North-South”. Tough policies of some countries make it necessary to redirect commodity flows along new logistic routes. The analysis of goods traffic promotion through the North-South corridor shows its serious competitive advantages in comparison with the Southern sea route in terms of transportation distance, time, and cost of delivery. The study analyzes the problems of the international transport corridor. These include technological, documentary, and infrastructural unresolved problems. The multivariant logistic route in the central part of the North-South corridor poses the problem of choosing the optimal route. The article analyzes the existing methods of route choice based on equal advantageous transportation distance and full cost for solving this task. The limitation of the listed methods leads to the search for a cost minimization function for a logistics route.

Simulation, Fabrication, and Testing of a Position-Sensitive Proportional Gas Chamber with Equipotential Parallel Wires with Similar Behavior as Micromegas Detectors

Different strategies exist for electron multiplication in a proportional radiation gas detector. In this work, the amplification region is formed by an array of equipotential stainless steel wires that were fixed at equal distance from a bared silver flat ribbon cable as the anode of the detector. The wires in this structure have the same role as the micromesh in Micro-Mesh Gaseous (Micromegas) detectors. Its fabrication method is simple and low cost. In this work, the amplification gain of the fabricated sample at different anode voltages was extracted, and the maximum achievable gain without electric discharge was measured to be M = 315 at 700 V. The proposed detector has an inherently two-dimensional positioning capacity, and the position sensitivity of the detector in one dimension was tested, the results of which show a good discrepancy with theoretical expectation. For the fabricated detector, the maximum number of charges before electric discharge was extracted (1 × 107) and compared with the best-designed Micromegas detector (6 × 107). These results clearly show that the proposed detector, despite its simplicity and cost-effective process, has a reasonable quality in comparison to the Micromegas detector.

Detection Methods for Multi-Modal Inertial Gas Sensors.

We investigate the rich potential of the multi-modal motions of electrostatically actuated asymmetric arch microbeams to design higher sensitivity and signal-to-noise ratio (SNR) inertial gas sensors. The sensors are made of fixed-fixed microbeams with an actuation electrode extending over one-half of the beam span in order to maximize the actuation of asymmetry. A nonlinear dynamic reduced-order model of the sensor is first developed and validated. It is then deployed to investigate the design of sensors that exploit the spatially complex and dynamically rich motions that arise due to veering and modal hybridization between the first symmetric and the first anti-symmetric modes of the beam. Specifically, we compare among the performance of four sensors implemented on a common platform using four detection mechanisms: classical frequency shift, conventional bifurcation, modal ratio, and differential capacitance. We find that frequency shift and conventional bifurcation sensors have comparable sensitivities. On the other hand, modal interactions within the veering range and modal hybridization beyond it offer opportunities for enhancing the sensitivity and SNR of bifurcation-based sensors. One method to achieve that is to use the modal ratio between the capacitances attributed to the symmetric and asymmetric modes as a detector, which increases the detection signal by three orders of magnitude compared to a conventional bifurcation sensor. We also present a novel sensing mechanism that exploits a rigid arm extending transversely from the arch beam mid-point and placed at equal distances between two side electrodes. It uses the asymmetry of the arch beam motions to induce rotary motions and realize a differential sensor. It is found to increase the detection signal by two orders of magnitude compared to a conventional bifurcation sensor.

Arrangement of Belleville Springs on Endplates Combined with Optimal Cross-Sectional Shape in PEMFC Stack Using Equivalent Beam Modeling and FEA

A set of Belleville springs integrated into an endplate plays a key role in a proton exchange membrane fuel cell (PEMFC) stack, which makes the applied assembly force smoother, resulting from the absorbed vibration and thermal expansion. The appropriate arrangement of Belleville springs is important in PEMFC stack design. The aim of this study is to establish an equivalent beam model to optimize the numbers and positions of Belleville springs to minimize endplate deformation. Based on this, a finite element analysis (FEA) model of the PEMFC stack is proposed to further optimize the cross-sectional shape of the endplate. For the endplate with two, three and four groups of Belleville springs, its optimal positions correspond to 0.17lin, 0.27lin and 0.5lin (lin is the equal distance between steel belts). In addition, the low thickness should be 2/3 of the high thickness of the curved endplate for a uniform contact pressure distribution as well as the high-volume-specific power. However, the curvature radius of the endplate arc is negative to the uniformity of the contact pressure distribution, and particularly the internal cells of the PEMFC stack. This study provides a design direction for endplates combined with Belleville springs in large fuel cell stacks clamped with steel belts.

Numerical Study for Enhancement of Heat Transfer Using Discrete Metal Foam with Varying Thickness and Porosity in Solar Air Heater by LTNE Method

A two-dimensional rectangular domain is considered with a discrete arrangement at equal distances from copper metal foam in a solar air heater (SAH). The local thermal non-equilibrium model is used for the analysis of heat transfer in a single-pass rectangular channel of SAH for different mass flow rates ranging from 0.03 to 0.05 kg/s at 850 W/m2 heat flux. Three different pores per inch (PPI) and porosities of copper metal foam with three different discrete thicknesses at equal distances are studied numerically. This paper evaluates the performance of SAH with 10 PPI 0.8769 porosity, 20 PPI 0.8567 porosity, and 30 PPI 0.92 porosity at 22 mm, 44 mm, and 88 mm thicknesses. The Nusselt number for 22 mm, 44 mm, and 88 mm thicknesses is 157.64%, 183.31%, and 218.60%, respectively, higher than the empty channel. The performance factor for 22 mm thick metal foam is 5.02% and 16.61% higher than for 44 mm and 88 mm thick metal foam, respectively. Hence, it is found that metal foam can be an excellent option for heat transfer enhancement in SAH, if it is designed properly.

Finite element analysis of the effect of type, number, and installation angle of FRP sheets on improving the flexural strength of concrete beams

Using FRP material to strengthen concrete beams is one of the best methods to prevent cracks propagation in the tensile zone. In this article, a concrete beam is modeled using the finite element software Abaqus. In order to investigate the effects of type, number, and installation angle of FRPs, a total number of 25 numerical models are considered. In these models, 3 types of covers made of GFRP, CFRP, and AFRP materials, including 6 and 12 sheets, are used at the installation angles of 30, 45, 60, and 90 degrees. Also, at the bottom of the beam in all the models, FRP layers are used to prevent the growth of cracks. After applying a constant load of 60 kN on all models, the stresses produced in the beam together with displacement at the middle of the beam, are investigated. The results showed that with an equal number of sheets and equal distance of installed sheets, the effect of FRP sheets on reducing displacement is greater at an installation angle of 45 degrees compared to that of a 60-degree angle. Also, this effect is greater at an installation angle of 60-degree angle compared to that of a 90-degree angle. Furthermore, by the addition of plates, the maximum lateral strain at the middle of the beam span is reduced up to 12.5 %. Also, CFRP material had a better performance compared to the two other types of fibers. The addition of prestressed FRP sheets to the specimens increases their strength. The load increase continues to the point wherein the beam fails due to the crushing of the compressive concrete. Adding the prestressed FRP sheets to the specimens increases the strength against the ultimate load from 5.4 % to 26.4 %, compared to the beam, which has internal confinement by the inner rebars.

Optimal Operation of a Distillation Process Through Extremum Seeking Control

In this work, extremum seeking control (ESC) is applied to optimize the operating conditions of a distillation column in continuous operation, to separate the components of an ideal binary mixture. The approach is based on an objective function that requires both the compositions of the distillate stream and bottom stream in an equal distance from complete purity. Numerical simulations show how the ESC drives the process to the minimum of the objective function, which is typically determined through the construction of a response surface of the objective function with respect to the process inputs. The performance of the standard ESC is compared with an accelerated version including a proportional action.