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Soil tillage is the most energy-intensive and costly process. Therefore, the creation of combined machines that perform multiple operations in one workflow is a pressing issue for today, the solution of which is inextricably linked to the integration of agricultural operations into one technological process that brings economic, organizational and agrobiological benefits. Based on the peculiarities of soil preparation for planting or planting crops as an object, and the need for further scientific design of the combined technological process of soil application of fertilizers, active crumbling and cultivation of root, plant residues and fertilizers as a subject, the purpose of scientific research analysis of the interaction of the rotor with the reservoir, determination and optimization of the basic parameters of knives, radius, rotational speed with a view to providing classic soil cutting and mixing with fertilizers. At State Agrarian and Engineering University in Podiya the design of the combined plow was developed. The technological process of their work combines the operations of deep plowing, the active grinding of the formation and the earning of root and crop residues, as well as the introduction of mineral fertilizers. As a result of researches, the angles of installation of the knife with respect to the radius of the rotor α, the angle of sharpening γ, the cutting angle ψ, the occipital angle ζ, the angle of conicity of the rotor β, the angle of displacement of the blades (rays) of the attachment, the magnitude of the transformation of the angle of sharpening, the analysis of the part of the sharpening , and according to its results the required speed of rotation at which the soil passes on the surface of the knife without loading is determined and the effect of its unloading is provided

Light metals such as aluminum alloys which are being broadly used in automobile sideways, aerospace production as well as segments in military. A light-weight metals prominent for energy consume reduction, efficiency of gasoline and oil increment and superior security to environment. The main utilization of aluminum matrix alloy components have been manufactured by the appropriate behaviors of high tensile strength, hardness, decent machinability, great cast-ability and excessive resistance of corrosion. In the present investigation dealing with casting and heat treatment processes of aluminum alloys 6063 by two different methods such as Sand casting and Die casting. The characterization of AA6063 are analyzed with help of destructive and non-destructive techniques. Finally the results indicates that die casted material gives better results when it is heat treated than the sand casted material.

Stealth aircraft use Stealth Technology in order to evade recognition by utilizing mix of highlights with the goal that Aircraft can invade with RADAR and furthermore decrease the deceivability in “radio frequency (RF) range”, sound and infrared visual. During the most recent decades, stealth technology has demonstrated to be one of the best methodologies to the extent the undertaking to escape radar systems is concerned. Stealth intends to evade the recognition or attempt to cover up, for planes, avoiding radar implied stealth. The idea utilized in the stealth innovation isn’t so difficult. It utilizes the guideline to retain and mirror the radar waves. Airplane redirects the radar waves in different ways and limits the radar waves which return back to radar. Another marvel which permits the air ship maintain completely the incoming radar wavelengths to inhabit the electromagnetic reincorporated energy in various way. The structure and material used to manufacture air ship choose the degree of stealth accomplish via air ship. The thought for the radar radio wire to release Radio energy that is then returned through any item that occurs to recognize. The time taken for the reflection to come is measure by the radar radio wire and it can tell how far off an object is.

This paper presents a new interior permanent magnet (IPM) rotor structure/ assembly which inherits from the Halbach magnet configuration and spoke-type IPM rotor to achieve a high saliency ratio and high torque/power density. A higher air-gap flux density and a higher saliency ratio are expected to improve torque density, while the rotor inner diameter can be maximized as much as possible to reduce core material consumption and increase internal space of the rotor. Accordingly, the electromagnetic performance of three motors consists of a unified stator but three different rotors, namely flux-concentrating rotor, Halbach array PM rotor and spoke-type IPM rotor is compared by finite element analysis (FEA). Due to the segmented structure of flux-concentrating PM rotor without magnetic bridges, the mechanical challenges are analyzed in detail for electric vehicle application. The stress analysis on the prototype design with fixing pins to hold the pole pieces validates the structural feasibility at 7200 r/min. Finally, a 72-slot/ 16-pole fractional-slot PM motor with new flux-concentrating rotor is manufactured and tested to verify its performance and feasibility. It can be concluded that the new rotor is superior to the spoke-type IPM and Halbach array PM rotor in terms of torque density and PM utilization.

To overcome the limitations of a traditional soft hip exosuit directly driven by Bowden cables or winding belts at two points, in this article, we propose a new soft hip exosuit design concept based on series-wedge-structures for energy-efficient walking and running during daily activities for elderly individuals. The series-wedge-structure is designed to improve the comfort of the wearer–exosuit interface and to passively adapt to the user's body curvature, with no hindrance during movement. The design and function, including the series-wedge-structure belt, series elastic cable drive actuator, and control scheme, are described. The presented soft exosuit, which is lightweight (1.4 kg) and comfortable, provides assistive torque for hip flexion by folding series-wedge-structures driven by Bowden cables. The series-wedge-structure-based hip exosuit adopts single actuation coupled to the Bowden cable pull mechanism with a series elastic actuator to drive both hip flexions based on the out-of-phase nature of the human legs during walking and running. The exosuit performance test results show that the proposed exosuit improves the comfort of the wearer–exoskeleton interface by minimizing the shear force and maximizing the exosuit–skin interaction force contact area. Three healthy subjects walked at a fixed speed of 1.25 m/s and ran at a fixed speed of 2.2 m/s while wearing the proposed exosuit with/without assistance and without wearing the exosuit to evaluate the biomechanical and physiological effects of the proposed exosuit assistance on locomotion. The metabolic rate with exosuit assistance was reduced by 10.9% for walking and by 6.2% for running compared with not wearing the exosuit.

As the wind turbine operates in harsh conditions, numerous of its components are critical and present an important downtime for maintenance. In this paper, we propose a fault diagnosis algorithm to detect and locate the defects affecting the generator rotor and the pinion of the gearbox lay shaft in a real 750 kW wind turbine drivetrain. The induction generator was used as a fault sensor for gear teeth damage. Through the use of the wavelet packet transform, and the local mean decomposition combined with the Fast Fourier Transform, the detection of gear meshing frequency in the stator current reflects teeth faults. Hence, the principal component analysis of the stator current gives a suitable classification for the gearbox states under different working stages. The obtained results have been significant, despite the use of a short duration and a low sampling frequency of the experimental data.

In this paper, an integrated drive converter of segmented-double-stator switched reluctance machine (SDS-SRM) with isolation and non-isolation charging capabilities for electric vehicle (EV) is presented. The proposed converter can not only reduce the number of the power switches, but also implement multiple operation modes. In non-isolation charging mode, the motor windings and existing power switches constitute a buck/boost converter to charge the battery. The appropriate rotor positions are obtained to achieve torque-free control, and the interleaved phase currents control method is introduced to reduce the charging current ripples. In isolation charging mode, the inner-stator is powered by the utility grid to drive the middle-rotor, and converts electrical energy into mechanical energy. While, the outer-stator is operated in generation mode to convert mechanical energy into electrical energy. The SDS-SRM is served as a rotating transformer to transfer the electric power to charge the battery with the galvanic isolation function. A low power proof-of-concept prototype platform is built and experiments are carried out to verify the effectiveness of the proposed integrated drive converter and the corresponding control schemes.

Due to current and future environmental and safety issues in space propulsion, typical propellants for upper stage or satellite rocket engines such as the toxic hydrazine are going to be replaced by green propellants like the combination of liquid oxygen and hydrogen or methane. The injection of that kind of cryogenic fluids into the vacuum atmosphere of space leads to a superheated state, which results in a sudden and eruptive atomization due to flash boiling. For a detailed experimental investigation of superheated cryogenic fluids, the new cryogenic test bench M3.3 with a temperature controlled injection system was built at DLR Lampoldshausen. After a first test campaign with high-speed shadowgraphy of flash boiling liquid nitrogen sprays, a laser-based Phase Doppler system was set-up to determine the spatial distributions of droplet velocities and diameters in highly superheated sprays. The spatial distributions revealed a core region with high mean velocities close to the injector orifice. With increasing distance from the injector orifice, the sprays develop a more and more monodisperse pattern. These distributions also showed that atomization due to flash boiling generates finer sprays with growing degrees of superheat. In certain spray regions, two droplet populations varying in their direction of motion, velocity and diameter due to possible recirculation zones were observed. The experimental data of flash boiling liquid nitrogen generated within this study provide a comprehensive data base for the validation of numerical models and further numerical investigations., Deutsche Forschungsgemeinschaft, Projekt DEAL

This article proposes a real-time method to control the contour error for industrial five-axis machine tools by combining the generalized predictive control (GPC) and the feedback correction (FBC) with dynamic con- tour error estimation (CEE). The CEE is developed by well considering the curves curvature and torsion based on Taylor series expansion and Frenet frame theory. By utilizing the spherical linear interpolation, the tool orientation and the tool tip position are synchronized with respect to the curve length. A novel dynamic foot point searching procedure is established to weaken the influences of the tracking errors magnitude on the CEE precision. To tackle the transmission effect, the GPC is adopted to predict the servo systems outputs, and then, the induced tool pose deviations, which are subsequently utilized to counteract the contour errors, are predicted by constructing Jacobian matrixes. Especially, the FBC loops are constructed to suppress the influences of disturbances and further to reduce the magnitudes of contour errors. Simulations and experiments are conducted to verify the effectiveness of the proposed methods.

The concept of electric-drive-reconstructed onboard charger (EDROC) potentially opens the door to harness the existing drivetrain in electric vehicle (EV) to do the job of battery charger, thus performing a remarkable value in commerce. In this paper, the pre- and post-fault operations of an EDROC is studied, which incorporates an asymmetrical six-phase permanent magnet synchronous machine (ASPMSM) drive. At first, the decomposed currents of machine in healthy and faulty cases are solved and their trajectories are depicted, indicating that a rotating field will exist if open-phase fault (OPF) occurs. Afterwards, a rotating field cancellation scheme based on the minimum copper loss criterion is proposed by rearranging stator currents, with two constraints under consideration that are responsible for generating pulsating field and balanced grid currents, respectively. Following this, a control scheme shared for both pre- and post-fault conditions is proposed, where the carrier-based modulation without any zero-sequence signal injection is employed. Finally, the proposed rotating field cancellation scheme is verified by experimental results.

A modified configuration for Permanent Magnet Assisted Synchronous Reluctance Motors (PMaSyRM) is studied in this paper. Conventionally, the PM materials are inserted in the flux barriers region of the rotor. Consequently, the PMs sizing parameters will be restricted to the available space that may limit the efficient use of PMs benefits. In this study, a portion of the rotor structure is replaced with an Interior PM (IPM) rotor so that an axially segmented integration of IPM and SyRM is obtained. Thus, the PMs design is performed specifically in the IPM segment independent of the SyRM scheme, while the SyRM segment remains PM-less. The main motivation of this concept is to improve the contribution of the PM material in the total torque as well as utilizing the special property of the proposed rotor configuration for pulsating torque reduction. A computationally cost-effective algorithm is proposed for the optimal design of IPM-SyRM motor by which a low-power design is carried out for a lightweight electric vehicle. The results for torque profile characteristics, PM volume, power-factor, and efficiency are compared with a conventional PMaSyRM that has been optimally designed as the reference case. Finally, a prototype is constructed to verify the theoretical analysis.

This paper presents two new energy saving control methodologies for Induction Motor (IM) based Electric Vehicles (EV) that exploits advantages from both Direct Torque Control (DTC) and Maximum Torque per Ampere (MTPA) control. While the first variant implements IM control through hysteresis controllers, the second variant employs a modulator to achieve constant switching frequency. For both the variants, a flux observer is carefully designed to minimize the effects of with IM parameter variations. Detailed torque ripple and power loss characteristics of IM drive controlled with the envisaged MTPA-DTC variants are also presented. The proposed techniques clearly show reduction in current drawn by the EV system in comparison with the existing techniques. IM drive is tested for fast acceleration and also the European Union (EU) urban drive cycle to assess the advantages offered by the proposed control techniques. Advantages obtained such as simple and fast implementation, high dynamic performance, reduced stator current, power loss leading to improved IM efficiency, reduced steady-state torque ripple followed by energy savings obtained in the EV are presented in the paper which can greatly benefit EV applications.

This paper proposes a non-smooth funnel control (NSFC) strategy based on the extended state observer (ESO) for motor-drive servo systems with unknown dynamics. These unknown dynamics, including the modeling error, the external disturbances, and the nonlinear friction, are considered as a lumped disturbance. For estimating the unknown states and the lumped disturbance, a non-linear bandwidth extended state observer (NLB-ESO) is developed. The non-linear bandwidth designed using the Gaussian function and the position observation error can deal with the ``peaking value problem" caused by the high observer gains. Furthermore, a funnel error surface is proposed based on the non-smooth error transformation and incorporated into the dynamic surface control design procedure, where the NSFC can prescribe the position tracking error in a funnel region with small steady-state error and overshoot, and short adjustment time. The non-smooth funnel error surface also avoids the singular problem in controller design by selecting the non-smooth parameter. Moreover, the stability of the closed-loop control system with the NLB-ESO is guaranteed by the Lyapunov theory. Comparative simulations and experiments show that the proposed NSFC can prescribe the tracking error in a funnel and ensure better tracking performance.

This paper reports on the possibility of performing Friction Stir Welding (FSW) without the usual immanent shoulder to enable FS processing to deep welding of narrow and labile structures and applications where backing is not possible. Requirements and prerequisites, advantages and limitations for Shoulderless Friction Stir Welding (SLFSW) are discussed and an industrial application of the joining technology is presented. For leaving the shoulder out, its central functions in FSW have to be transferred to the pin. The resulting tool design of SLFSW is comparably small and slim and so reduces contact area and effective lever and in turn forces and heat input during processing. SLFSW allows welding paths almost at the edge of components and enables a complete and gap-free joining while a deformation of overhanging structures can be avoided. Compared to standard FSW processes, force reductions of about 80–85 % and power reductions of about 75-80 % were found in this study for a 6.5 mm deep weld opening up additional potential for integration with other spindle processes like milling. The locally very limited process impact of SLFSW resulted in comparably low distortion with a part precision reached of +/- 0.05 mm., Projekt DEAL

Background During shortages of filtering face pieces (FFP) in a pandemic, it is necessary to implement a method for safe reuse or extended use. Our aim was to develop a simple, inexpensive and ecological method for decontamination of disposable FFPs that preserves filtration efficiency and material integrity. Material and methods Contamination of FFPs (3M Aura 9320+) with SARS-CoV-2 (1.15 × 104 PFUs), Enterococcus faecium (>106 CFUs), and physiological nasopharyngeal flora was performed prior to decontamination by submersion in a solution of 6 % acetic acid and 6 % hydrogen peroxide (6%AA/6%HP solution) over 30 minutes. Material integrity was assessed by testing the filtering efficiency, loss of fit and employing electron microscopy. Results and Discussion Decontamination with the 6%AA/6%HP solution resulted in the complete elimination of SARS-CoV-2, E. faecium and physiological nasopharyngeal flora. Material characterization post-treatment showed neither critical material degradation, loss of fit or reduction of filtration efficiency. Electron microscopy revealed no damage to the fibers, and the rubber bands’ elasticity was not affected by the decontamination procedure. No concerning residuals of the decontamination procedure were found. Conclusion The simple application and widespread availability of 6%AA/6%HP solution for decontaminating disposable FFPs make this solution globally viable, including developing and third world countries.

Laser sintering devices have been increasingly used to fabricate the metal frameworks of metal-ceramic restorations. In the fabrication process, the sintering layer thickness is an important parameter; however, information on how it may affect the flexural strength of metal frameworks remains limited.The purpose of this in vitro study was to evaluate the flexural strength of 3-unit and 4-unit cobalt-chromium (Co-Cr) metal frameworks laser sintered with 20-μm, 30-μm, and 40-μm layer thicknesses.Three-unit and 4-unit master metal die models with premolar and molar abutments were prepared through direct metal laser sintering (DMLS). A total of 40 metal frameworks (n=10 for each metal die model) were fabricated by the lost-wax technique (group C, served as the control group) and through DMLS with 20-μm, 30-μm, and 40-μm layer thickness (experimental groups LS20, LS30, and LS40, respectively). Each metal framework was cemented to a master die with a polyvinyl siloxane impression material and then subjected to a 3-point bend test at a crosshead speed of 1 mm/min. The yield force of each metal framework was used to calculate the flexural strength. Data were statistically analyzed by using 1-way ANOVA followed by a Tukey honestly significant difference (HSD) test and an independent-samples t test (α=.05) The microstructure of the fracture surface was evaluated by scanning electron microscopy.Group C reported the lowest mean flexural strength (P.05), whereas group LS20 reported the highest mean flexural strength, although no significant difference (P.05) in flexural strength was observed among the DMLS groups. The 3-unit metal frameworks exhibited a statistically significant higher mean flexural strength than the 4-unit metal frameworks (P.05).The sintering layer thickness did not significantly affect the flexural strength of the laser-sintered metal frameworks. However, the DMLS groups reported a higher mean flexural strength than the cast group.

A high power, high frequency wireless power transfer system for electric vehicles is proposed in this paper with lightweight and compact coil design. Leveraging a multi-layer non-uniform self-resonant coil, no external capacitor is needed for compensation and the high frequency conduction loss is mitigated by sharing current between multiple copper layers. The analytical model for the proposed coil is provided, and prototype coils with 200 mm radius are fabricated and tested, achieving quality factor over 450 at 3 MHz. The optimized design for both coils and a GaN-based power stage are detailed and validated experimentally. Experimental tests show 95.2% dc-dc efficiency with 6.6 kW power transferred across a 100 mm coil-to-coil distance with 52.5 kW/m2 power density. The system demonstrates the first 6.6-kW WPT system for EV charging using compact self-resonant coils at MHz.

A multi-sensor data fusion method is investigated for bearing fault diagnosis of a switched reluctance motor (SRM) of an electric vehicle (EV) powertrain under varying speed conditions. The accumulative rotation angle of the SRM rotor is estimated by fusing the synchronous sampled current and vibration signals. The time-domain vibration signal is then resampled on an angular domain, and the bearing fault type is identified on the envelope spectrum of the resampled signal. An experimental setup is designed to validate the performance of the proposed method compared with the traditional ones. The practical EV working conditions including driving, coasting, and braking are considered in the experiments. Results indicated that the proposed method successfully diagnoses the SRM bearing faults under random and complex conditions. The method is promising for online SRM fault diagnosis under varying speed conditions as it requires no extra tachometer, specifically when the sensorless control strategy is adopted.

Fast recognition of integrated circuits markings is an essential but challenging task in electronic device manufacturing lines. This article develops an adaptive deep learning framework to facilitate the fast marking recognition of IC chips. The proposed framework contains four deep learning components, namely chip segmentation, orientation correction, character extraction, and character recognition. The four components utilize different convolutional neural network structures to guarantee excellent adaptivity to a wide range of IC types, and mitigate the influence of the low-quality chip images. In particular, the character extraction model is comprised of two improved label generation strategies and a proposed border correction method, so as to accommodate tiny scale chips and compactly printed markings. Experiments for a set of chip images from a real laptop manufacturing line demonstrate the superiority of the proposed framework to the state-of-the-art models and the effectiveness of handling a great diversity of chips.

Focusing on the accurate size, direction and position of dynamic meshing impact, an innovative semi-finite element method (semi-FEM) forecasting model is proposed for spiral bevel gear transmission under both high speed and heavy load conditions. To distinguish with the traditional rotor dynamic analysis focusing on vibration effect for global system, a new dynamic loaded tooth contact analysis (DLTCA) focusing on loaded contact effect for local contact area is proposed for the geometric boundary forecasting. Where, DLTCA shows a systematically time-varying characteristics including the dynamic loaded contact pattern, pressure, transmission error. Considering tooth flank flexural behaviors, data-driven tooth flank simulation and finite element modeling is developed by using universal motion concept (UMC) machine settings. At each finite element in a local geometric boundary, the dynamic compatibility and equilibrium equations are established as a semi-FEM dynamic meshing impact forecasting model. Moreover, for a dynamic transmission system, a basic judgement criterion is firstly developed. Then, the improved simplex method is applied to solve the established model for the dynamic meshing impact size evaluations including transmission error, torque, angular velocity, and acceleration. Finally, numerical and test instances are provided to verify the proposed method.

A non-isolated fast charger is proposed for electric vehicle (EV) battery system. The leakage current can be reduced by the novel charging system without bulky transformer. A zero sequence voltage control method is developed to stabilize the common mode voltage thus reduce the leakage current. The proposed fast charger includes two energy conversion stages: DC/DC converter for battery side control; DC/AC converter for grid interface and common mode voltage control. The parameters of the system with LCL filter are analyzed and optimized for a better performance of grid interface. Grid service functions are designed for the fast charger to provide grid voltage/frequency compensations. High power (22kW) and high efficiency 99% are achieved with low leakage current 20mA. The experiments are implemented to verify the proposed fast charger system.

This paper investigates the thermal environment of launch pads during rocket takeoff. The rocket plume model is set up using the three-dimensional Navier–Stokes equations and realizable k−e turbule...

This paper proposes a strategy to safely turn off an electric drive system in case of a fault without destroying the power module and the electric machine. Classic turn-off strategies like Active Short Circuit (ASC) and Freewheeling (FW) are adopted as state of the art for electric vehicle applications. However these methods cause either high currents in the machine or over-voltage in the DC-link capacitor, the system should be designed to withstand these unwanted effects making them more expensive. The novel method proposed in this study mitigates both over-voltage and over-currents, thereby achieving a smooth transition from torque control to a safe state. The proposed method can be implemented almost cost neutral with respect to the state of the art methods. In this method, voltage-vectors are identified with respect to the position of the current-vector, which can either charge or discharge the DC-link capacitor hence keeping both the DC-link voltage and stator-currents to a safe value. The proposed strategy is analysed through simulations with a combined inverter and machine model. The simulation model includes skin-effect loss models which are essential for the accurate calculation of the DC-link voltage. Measurements were done on an electric drive system to validate the strategy.

The electrostatic tractor has been proposed to touchlessly remove space debris from geosynchronous orbit by taking advantage of intercraft Coulomb forces. A controlled spacecraft (tug) emits an ele...

Low fuel regression rate is one of the major drawbacks of hybrid rocket motors. In this study, a novel injector concept is proposed to provide a substantial enhancement in the fuel regression rate....

At present, the surface precision requirements for mold and die parts are extremely high. Especially in the precision mold and die cavity for ELD lenses, several mirror surfaces for automotive lens parts, and general camera lenses that required a few tens or a single nano-level like a mirror-finished surface. This final process is difficult to achieve with the conventional cutting edge of ball-nose end mills. In addition, it is commonly performing a very long time by manual polishing of the skilled worker after machining. To the problem, we purposed to develop a sintered polycrystalline diamond (PCD) rotary tool with a simple spherical cutting part. This PCD tool is a novel method for the final process of the small molds and dies cavities with high precision. A distinctive feature of its cutting can achieve a mirror-finished surface by full automation on a CNC machining center. This study aims to clarify the basic machining characteristics and verify its effectiveness on the hardened stainless steel commercial STAVAX with the hardness of 54 HRC for small mold and die cavities. As a result, we can clarify the chip generation mechanism, finish surface accuracy, internal crystal structure state, and residual stress characteristic of this processing method. It also shows that the manual problems related to mirror finishing of the precision mold and die cavity can be solved under the actual mold manufacturing process by consecutive conditions.

Electric Machine Emulation (EME) is becoming a popular solution in advanced testing and validation of power-electronics-based machine drive systems. In terms of a typical EME, the stator current references are firstly calculated in response to the sampled terminal voltage, and then are electrically generated by power electronics converters. In this type of structure, closed-loop current control (CLCC) and low-pass sampling for voltage are inevitably introduced, resulting in distortion in frequency-domain behaviors of EME. Consequently, the steady-state performance under high fundamental frequency, and the dynamic performance under load transients, may deviate from those of target machine system. In this paper, the bandwidth limitations of the typical EME are identified and analyzed in detail, and a novel structure that realizes full-bandwidth mission profile emulation is proposed. Theoretical analyses are given to prove that the frequency-domain characteristics of the proposed structure would be identical to the actual machine systems, which allows for the extended operating range of mission profile emulation. Simulation and experiment results are provided to validate the effectiveness of the proposed method.

Background: As the basis of mechanical manufacturing, large-scale machine tools are being developed for improving processing accuracy, load-bearing capacity and rigidity. Hydrostatic thrust bearing, hydrostatic guide and hydrostatic ram are important components of large machine tools; with the continuous improvement of product accuracy requirements, the research on the hydrostatic thrust bearing, hydrostatic guide and hydrostatic ram has become more important. Objective: This paper presents the current research on hydrostatic thrust bearing, hydrostatic guide and hydrostatic ram to highlight the importance of hydrostatic ram in improving the machining accuracy of machine tools. The study aims to lay a foundation for research and development of hydrostatic ram in the future. Methods: Firstly, the hydrostatic bearing technology is introduced. Secondly, the research status of hydrostatic thrust bearing, hydrostatic guide and hydrostatic ram is presented to provide theoretical basis for improving the processing performance of rest ram. Result: Deformation compensation and thermal deformation compensation of hydrostatic ram have been studied more. Most of the research study focuses on the accuracy of hydrostatic ram, but less on the bearing performance of hydrostatic ram. Conclusion: Breakthroughs have been made in the research on precision control and structural form of the hydrostatic bearing at home and abroad. Most scholars take the ram of Computer Numerically Control (CNC) boring and milling machines as the research object, but there is less research on the ram of vertical lathes. Therefore, the academic circle should pay more attention to the bearing performance of the hydrostatic ram of vertical lathes.

In this paper, a novel winding switching control strategy is proposed to extend the speed range of a consequent-pole ferrite-PM hybrid-excited machine (CPFPM-HEM) for electric vehicle application. The key is that in low-speed range, the AC armature winding and DC field winding are connected in series to achieve large starting torque, while in high-speed range, DC field winding are injected with adjustable DC currents to realize variable speed constant voltage of AC armature winding. Furthermore, consequent-pole rotor is used to reduce the usage of the permanent magnet (PM). In the meantime, ferrite PMs are used to replace rare-earth PMs to reduce the cost with the shortage of rare earth resources. In this paper, the machine configuration, operation principle with dual excitation sources, flux modulation principle and winding switching strategy are illustrated in detail. Then, the electromagnetic performance of the CPFPM-HEM in different speed ranges is investigated. Finally, the speed range extension with winding switching strategy is verified by the Maxwell/Simplorer co-simulation.

A novel waveguide-to-microstrip inline transition was proposed using a wedge-waveguide iris to form an ultra-compact U-bend waveguide. The wedge-waveguide iris not only functioned as a wide wall of the height-reduced waveguide for the E-plane probe, but also played a critical role in impedance matching and parasitic resonance suppression. The working principle was investigated through theoretical analysis and full-wave simulation, and the relevant design processes for the transition were discussed. Moreover, two back-to-back transition prototypes, one working at the W-band and the other working at the WR4.3 band, were designed, fabricated, and measured. The back-to-back prototypes obtained an insertion loss of less than 0.8 and 1.2 dB, with a return loss better than 15 dB in the W-band and WR4.3 band, respectively. The measurement results were consistent with simulation results. A miniaturized 110-GHz tripler incorporating this transition for inline output was fabricated. A conversion efficiency of 2.5%-3.6% was achieved in 90-120 GHz at 100-mW driving power.

This paper presents experimental results from a model rocket combustor that uses a gas-centered swirl-coaxial injector element injecting warm oxygen and ambient temperature RP-2 fuel with 900 psia ...

Automotive air conditioning heat pump systems draw increasing attention as an alternative to conventional electric heaters. Once the air temperature falls below the freezing point, frost begins to form on the surface of the evaporator. The accurate defrost strategies could avoid heat exchange efficiency reduction and prevent heating capacity from decaying, which are the main factors affecting the energy efficiency of electric vehicle heat pump systems. The frost characteristic on micro-channel heat exchanger of the electric vehicle heat pump system is tested, and a novel defrosting strategy which is based on the dimensionless analysis method is introduced too. Conclusions could be drawn as following: a correlation that considers the effects of ambient parameters and structural parameters has been developed to predict the frost thickness on fins with dimensionless analyses. Based on this correlation, the relative error and the RMS error between the experimental data and the predicted value are 8.44% and 12.54%, respectively; the effective blockage ratio (EBR), a parameter that accurately reflects the blockage ratio and directly linked to the system operation state, is first proposed. Through the analysis between the EBR and system heating capacity, it can be concluded that the optimal defrosting start-point is identified as the EBR reaches 30%. With this method, the defrosting start-time can be found accurately and effectively to avoid unnecessary defrost cycles, thus leading to a highly efficient operation and low energy consumption for the electric vehicle heat pump system.

In the context of workplace safety, activated carbon in the fiber form (i.e., activated carbon fiber, ACF) represents an alternative adsorbent to granular activated carbon (GAC) for use in organic vapor respiratory protection devices. ACFs are high surface area carbonaceous materials that are often available in a self-supporting non-woven form. The physical form of ACF suggests the potential for a filtration medium that is capable of supporting both organic vapor adsorption and particulate filtration.To study the application of these materials in respiratory protection devices, ACFs (ACFF 1200 m2/g, ACFF 1800 m2/g, and ACFF 2000 m2/g) were challenged with representative organic vapors (toluene, hexane, and methyl ethyl ketone (MEK)) at an occupationally relevant concentration (200 ppm). Breakthrough curves were generated for at least three different bed weights of adsorbent. Pressure drop (i.e., the resistance across the filtration media) was also measured to determine maximum ACF bed depths for use in respiratory protection devices.Breakthrough experiments indicate that ACFF 2000 has the highest adsorption capacity for toluene (381 mg/g), followed by ACFF 1800 and ACFF 1200 (344 mg/g and 239 mg/g, respectively). A similar trend was observed for hexane: 221 mg/g, 196 mg/g, and 146 mg/g for ACFF 2000, ACFF 1800, and ACFF 1200, respectively. ACFF 1200 showed the highest adsorption capacity for the polar adsorbate MEK (168 mg/g), followed by ACFF 1800 and ACFF 2000 (166 mg/g and 147 mg/g, respectively). Based on the constraints of pressure drop, it seems unlikely the exclusive use of ACF in a filtering facepiece respirator can provide an adsorbent mass sufficient for full shift protection against organic vapor contaminants at or above the legally enforceable permissible exposure level (PEL). Nevertheless, the incorporation of ACF into a facepiece respirator appears promising for "nuisance odor" applications; i.e., the further reduction of organic vapor concentrations when workplace exposures are already below PEL concentrations. Implication StatementThis research brings innovation to the field of occupational health and air pollution control technology by investigating the adsorption performance of activated carbon fiber (ACF) media in the context of worker respiratory protection. ACF properties such as high specific surface area (m2/g), high permeability to airflow, and rapid adsorption kinetics make it ideal for use in thin, N95-style respirators for organic vapors. Respiratory protection is an exciting and relevant application for ACF media. A lightweight adsorbent such as ACF, if incorporated into an N95-style respirator, could potentially provide nuisance-level VOC protection in a physical form that is accessible to workers and consistent with OSHA's voluntary use provisions for facepiece respirators. The research presented in this manuscript represents one of several steps planned in the characterization of ACF media for this particular application.

Information Technology have to be an enabler of every activity. With the information technology, the effectiveness and efficiency of work shoultd be increase. The obstacles faced, with the existence of information technology, can be an alternative solution. SDN Hurip Jaya 03 Babelan is a school located on the north coast of Bekasi Regency. This school has a challenge where cable internet access from Provider has not yet entered so that educators and education staff, students use independent resources for internet access. Administrative and learning activities already use computers but have not utilized cloud applications such as google forms, google classroom, and shorter url applications for learning e-learning. The educators and education staff are also still working with computers in typing so that their work is less effective. The solution we provide is to share knowledge, knowledge, experience and resources in providing solutions to existing problems. The activities that have been carried out are providing wifi modem and usb wifi resources for internet access, training in fast typing the 10 finger method, using google forms and google classroom for administration and learning, as well as the bit.ly application for naming links to make reading easier. We hope that if the material presented can be trained and applied seriously, it will certainly be useful in supporting administrative and learning activities.

Manufacture of a transition hybrid coupling from two different steels, medium carbon S355J2 and stainless 316L, has been demonstrated using two different solid-state joining routes, forge welding (FW) and rotary friction welding (RFW). An additional manufacturing route, electron beam welding (EBW), was also employed in investigating its feasibility for such application. Mechanical and microstructure properties of the final components manufactured from the three different routes have been compared. Finite element (FE) analysis was utilised to determine optimal geometries for the FW and the RFW preform rings and identify optimal parameters for both processes. Of the three manufacture routes, the FW produced an instant diffusion-like bond with a single forging stroke on a 2100T screw press with the thinnest weld interface and most uniform hardness distribution at either side of the joint. The RFW part, manufactured on a 125T RFW machine, also exhibited a very thin weld interface, yet slightly thicker compared to the FW case, with small variations in the hardness distribution at either side. The EBW produced markedly thicker weld interface compared to the two solid-state routes. The EBW part exhibited significant variation in hardness distribution across the weld exhibiting peak hardness in the weld indicating requirements for a post-weld heat treatment (PWHT). Both the FW and the RFW process routes exhibited very uniform micro-hardness and microstructures across the weld interface in contrast with the EBW process in as-manufactured condition.

This paper presents the influence of wire electrical discharge machine (WEDM) cutting parameters on the magnetization characteristics of electrical steel. The demand for electrical steel keeps increases because of the high demand of electrical motor and transformers for electric vehicle and smart grid applications. The magnetization characteristics of the laminated steel used in these machines have dominates the performance of these machines. The cuttings methods and cutting parameters have huge role in deciding the magnetization characteristics. In this work, WEDM is used to cut the electrical steel in to small pieces. The cutting parameters such as current, feed rate and on-time of WEDM are varied by keeping two of these parameters fixed and one varied. From the electrical steel sheet, 18 sample small electrical steel pieces are obtained at various cutting parameters of WEDM. The magnetic field – magnetization characteristics are obtained using vibrating sample magnetometer (VSM). This analysis shows that higher current, lower on-time and higher feed rate is providing higher magnetization.

Covid-19 has become one of the most severe diseases causing the acute respiratory problems that has even killed millions of people worldwide. It was declared as the ongoing pandemic by the World Health Organization. It is an infectious virus which can be transmitted by sneezing, coughing and exhalation of air by any infected person. There are certain places where there are very high chances of rooms becoming contaminated like hospital rooms. In this context, we studied the transmission of covid-19 particles in an ICU room. In this paper, we have considered the combined effect of both of air-conditioning (AC) and a ceiling fan in the room. The infected person can transmit the disease when under influence of fan and AC, the work highlights the flow of aerosol particles considering the combined effect as well as the individual effects of fan and AC. The results also emphasized that the aerosol particles flow have a promising application in sanitizing the room.

To pursue high efficiency for wind turbine and harness more energy from wind, the wind power generation system has been designed larger and larger. With length scale increasing, the natural frequency of blade will be lower and changing dramatically with rotational speed, which will threaten the stability of the blade and turbine. However, in the previous research, the parametric, analytical, and quantitative study of centrifugal stiffening effect is rare to see. As a result, the current research has comprehensively studied the centrifugal stiffening effect on the structural characteristics of large wind turbine blade. Specifically, the equivalent rotating wedge beam model has been proposed for composite wind turbine blade. Based on the proposed wedge beam model and Rayleigh-Ritz method, the natural frequency variation curve has been derived and verified by ANSYS 3D simulation results. The parameters, including blade length, stiffness-mass ratio, and aspect ratio, affecting the natural frequency curve have been uncovered and analysed. It was found that the centrifugal stiffening effect has a great impact on the fundamental frequency of blade, e.g. 10% for NREL 5 MW, while it has less impact on other modal frequencies. The variation curve of fundamental natural frequency can be approximated by parabola. The product of the parabola curvature and fundamental frequency is found to be approximately constant for both NREL 5 MW and WindPACT 1.5 MW turbine blades. This research will provide guidelines for the resonance avoidance design of large wind turbine blade in the future.

It has been demonstrated theoretically and experimentally that the Vehicle-to-Grid (V2G) enabled electric vehicle (EV) charger is of a reactive power compensation ability with a battery or capacitor connected. To exploit the aggregated reactive power V2G abilities of massively dispersed EV chargers, a distributed model predictive control (DMPC) strategy applying to both balanced and unbalanced distribution networks (DNs) is proposed to integrate them into real-time DN voltage regulation. Firstly, based on the instantaneous power theory and voltage sensitivity matrices, a voltage regulation model considering the reactive response of EV chargers is established without violating the normal EV active charging demands. Then, a completely distributed framework is achieved by DMPC, in which prediction information and calculation results are shared in a Peer-to-Peer (P2P) way to realize the asynchronous broadcast. The proposed model and techniques are validated by numerical results obtained from the IEEE European low voltage test feeder system. The case studies indicate that the proposed DMPC is robust to communication latency (CML) and works effectively in both balanced and unbalanced DNs without any control center, which is a significant advantage for the promotion of real-time reactive power V2G in DNs with irregular user integration and relatively poor communication infrastructure.

Thermal management of electrical machines is an important issue to improve electromagnetic performance, reduce system size and prolong lifetime. Based on the equivalent thermal circuit (ETC) and computational fluid dynamics (CFD) methods, the temperature rise characteristic of a high-speed stator-permanent magnet-type flux switching (HS-SPMFS) machine for fuel-cell electric vehicle compressor is predicted. Firstly, the structural features, key dimensions, material properties and heat generation rate of the HS-SPMFS machine and its cooling system are introduced. Secondly, the ETC model of the machine with a liquid cooling channel is proposed, and the size of the cooling system is preliminarily designed. The influence mechanism of the number, size and flow rate of the water channel on the convective heat transfer area, convective heat transfer coefficient, water head loss and winding temperature rise is revealed. On this basis, combined with the CFD method, the temperature distribution of the machine is studied, and the detailed temperature distributions of each component of the machine are obtained and verified by the ETC method considering the cooling system. Finally, a HS-SPMFS machine prototype is manufactured and the temperature test platform of the prototype is built. The temperature rise behaviors of the machine under different working conditions are tested, verifying the theoretical analysis and the prediction methods.

Methane–oxygen burning is considered for many future rocket engines for practicality and cost reasons. As this combustion is slower than hydrogen–oxygen, flame ignition and stability may be more difficult to obtain. To address these questions, numerical simulation with realistic chemistry is appropriate. However the high pressure and turbulence intensity encountered in rocket engines enhance drastically the stiffness of methane oxy-combustion. In this work, Analytically Reduced Chemistry (ARC) is proposed for accurate chemistry description at a reasonable computational cost. An ARC scheme is specifically derived for typical rocket engine conditions. It is validated by comparison with its parent skeletal mechanism on a series of laminar flames. Then the numerical stiffness of chemistry is overcome with an original approach for time integration, allowing to run simulations close to the acoustic time step whatever the chemical stiffness. It is demonstrated on laminar cases that the flame structure is well preserved, and that numerical stability is ensured while decreasing significantly the computational cost. The performance of ARC with the fast time integration method is finally demonstrated in a 3D Large-Eddy Simulation of a lab-scale Liquid Rocket Engine combustion chamber, where a detailed flame analysis is conducted.

Recently, researchers have devoted more attention to supercapacitors (SCs) to integrate with batteries in energy storage systems (ESSs) for vehicle applications. In this study, we attempted to characterize the use of SCs in the ESS for a PEM fuel cell vehicle equipped with an alternator to maximize the performance of regenerative braking. We applied lithium-ion batteries (LIBs) and SCs as energy storage devices to examine their effect on ESS. Then we used a hysteresis brake to apply controllable braking force on the flywheel to form hybrid braking (HB) and made efforts to study its behavior to suggest a braking control strategy. We also ran the whole system over the rotational speed to cover the range of driving speed. At last, we sized the SCs for the most commonly used fuel cell electric vehicle (FCEV) in Korea, i.e., Hyundai NEXO, based on the results obtained from the above study by alternator efficiencies.

Fused deposition modeling (FDM) using Acrylonitrile Butadiene Styrene (ABS) polymer as filament is gaining a distinct advantage in manufacturing industries because of its ability to manufacture parts with complex shapes without any tooling requirement and human interface. Present research work aims to develop an alternative FDM filament using nylon 6, Al powder, and Al2O3 powder, which is to be used in existing original equipment manufacturer (OEM) FDM system without changing hardware/software of the system. Taguchi L9, orthogonal array approach, has been used to study the effect of input process parameters, i.e., proportions of filament ingredient, barrel temperature, and die temperature on mechanical properties of filament developed. Proportions of filament ingredients are found to have a significant effect on tensile strength, Young's modulus, and percentage elongation. The required filament has been successfully developed, having more improved properties. The resulting composite filament prepared by extrusion was found to work well with an FDM machine.

The accumulation of dust and scrap in the floors of workshops and warehouses creates untidiness and many occupational hazards. To have a dust free and safe working environment inside the workshop, it is necessary to sweep and clean them periodically. Mostly the cleaning is done using hand sweepers, ride on sweepers and walk behind type sweepers. The process of sweeping can be automated in order to minimize the effort of human. The presently available electrically operated sweepers occupy large space and it becomes difficult to operate in congested places. The machine should be compact so that it can move to any place with ease. The robotic sweeper consists of a cylindrical brush and two side brushes. The cylindrical brush is connected to DC motor through pulley and V belt. The miter gears are used at the ends of the cylindrical brush to transmit the power to the side brushes which rotates perpendicular to cylindrical brush. The robotic sweeper is controlled using Arduino, drives and Bluetooth module.

Computer Numeric Control (CNC) machine tools such as CNC milling machines and CNC turning centers produce components with a higher dimensional precision and accuracy when compared to traditional machine tools. The precision, accuracy of the dimensions are still governed by factors such as geometric errors, cutting forces induced errors and thermal errors. Thermal errors are a major contributing factor to dimensional deviations of the machined component. The heat generating sources of the machine tool which include spindle ball bearings, spindle motor, the axes motors, transformer pack, coolant pump, lubricant pump among others. The ambient temperature and weather also play a role in inducing thermal errors in a machine tool. The heat generated at these sources gets transferred to the adjacent elements of the machine tool causing them to distort or deform. These distortions or deformations of the various machine tool elements produce a cumulative effect which leads to the increase or decrease of the gap between the tool and work piece resulting in dimensional deviation in the final machined component. In the current work an attempt has been made to compensate for these thermal errors by building a prediction model based on experimentally measured diametrical and temperature data. Multiple linear regression has been used to create the prediction model, where the diametrical deviations were considered as dependent variables and temperature data was considered as independent variables. Least squares method is employed in multiple linear regression to obtain regression coefficients which would then be used in a mathematical equation to determine the deviation between tool point and work piece, which can be compensated to maintain the dimensions of the machined components. Four case studies were carried out in this work. Logarithmic transformation was used in the final case study to transform non-linear data into linear data which lead to consistent model behaviour when applied to several hours of test data.

The dual-parameter sensors based on topological ring structure are proposed and experimentally demonstrated, which has obvious advantages in relative humidity (RH) and displacement measurement. The topological ring structures are composed of two separated optical microfiber couplers (OMCs) as independent sensing units. The two OMCs are connected by two 30 cm length single-mode fibers (SMFs). The first sensor is formed by introducing OMC into the loop resonator (LR). The second sensor is constructed by introducing OMC into the Sagnac interferometer (SI). The LR-OMC and SI-OMC structures are made by splicing the two ports of OMC with two ports on one side of the different central axis. The coupling coefficient and effective refractive index (ERI) of OMC vary with RH and displacement. The reason for the wavelength shift caused by RH is that water molecules trigger the change ERI of the OMC evanescent. Furthermore, the RH measurement is realized without any humidity-sensitive material. Here, we present a topological ring structure that can measure two parameters discretely, eliminating the problem of RH and displacement crosstalk. The LR-OMC structure and SI-OMC structure have different RH and displacement sensitivity. The proposed topology sensors could find applications in the multi-parameter RH and displacement sensing due to their simple fabrication and low cross-sensitivity.

For an inductive power transfer (IPT) system used in electric vehicle (EV) charging, the receiver is usually equipped with a shielding structure to reduce eddy current loss in the chassis. However, the addition of shielding structure may significantly reduce self-inductance and mutual-inductance, and the eddy current on it can also produce power loss. To maximize the efficiency of IPT system used for EV charging, this study firstly established and analyzed the equivalent circuit model of IPT system. Then, 3-D model of IPT system with a steel plate and aluminum shielding is established in finite element analysis software, and the simulation result shows how the ohmic loss on coils and the iron loss on steel plate changes after the addition of the shielding structure. Afterward, a practical method of optimizing aluminum shielding structures parameters is proposed to maximize efficiency of IPT system with steel part and aluminum shielding, taking iron loss on steel part and aluminum shielding both into account. Its worth noting that variation of inductance caused by different shielding structure parameters requires different resonant capacitance values, which increases the complexity of the optimization procedure. To solve this problem, this paper presents a new efficiency calculation method by finite element analysis (FEA) to simplify the simulation and optimization procedure. Finally, experimental validation was performed on a 3-kW wireless charging prototype, and the correctness of proposed theory and design method in this paper were verified.

Productivity in the press tool shop is always the main stream especially in the case of products which needs more than one operation. To improve the productivity, modern day press tool shops are using the progressive dies. These dies are generally preferable to performs operations in series. The present study aims to reveal the design and analysis of various parts on the progressive die such as blanking die & punch; piercing die & punch. For this, an attempt has made to design the progressive die for strips of Aluminium (4032-T6) of 1 mm thickness. The study includes the discussion on material of the strips, press tool design procedure and the mathematical calculations. For the designing and analysis purpose, the SOLIDWORKS software is used. Besides, the study reveals the maximum value of the stress and displacement on such parts.

Combined with a common fuel binder, solid hypergols can simplify the overall complexity of hybrid rocket engines, as the fuel grain can be ignited and reignited without any external power source or...

A significant part of an automobile is the gear box (tractor) casing. The primary objective of using the Gearbox casing is to embrace and allow the transmission of the Gearbox. The Gearbox is a mechanism that regulates speed or torque between the flywheel and the differential. The main shaft and lay shaft with gears equipped embraces the gear box. This paper deals with the modeling and study as an alternative material of the gear box casing for a tractor with E-Glass. Through the development of the simulation software platform ANSYS, it is analyzed statically with different design parameters such as web thickness, gear box housing depth and gear box housing thickness. In order to determine the stress produced and deformation degree, the gear box with traditional Grey cast iron is analyzed; it is then compared with the housing of the E-Glass Gear box. The outcome will be studied and evaluated after study, various combinations of design parameters were used to achieve the design that minimum output in failure at higher load s has better deformation characteristics. Finally, in order to design the gear box housing, an optimized design parameter is obtained.[1]