The 6-DOF vibration isolation platform (VIP) is used to isolate vibration in the processing and manufacturing of semiconductor chips, especially electric vehicle chips. The 6-DOF VIP has the characteristics of high position accuracy, fast dynamic response, and short motion travel. In this paper, a novel four-quadrant Lorentz force motor (FQLFM) applied on the 6-DOF VIP is proposed. The structure of this LFM has a high force density, low force fluctuation, and low coupling force. First, the basic structure and operating principle of the proposed FQLFM are presented. Secondly, the expressions of the magnetic field and electromagnetic force are obtained based on an equivalent current model and the permanent magnet mirror-image method (PMMIM). Thirdly, the magnetic field and electromagnetic force characteristics of the proposed FQLFM and an LFM with a traditional bilateral structure are analyzed and compared. The relationship between the force and displacement of the FQLFM is investigated.... [more]

This paper proposes a novel multi-phase single-turn permanent magnet synchronous motor (MSPMSM) to meet the stringent requirements of electric aircraft, such as high power density, high torque, and low mass and volume. The MSPMSM features a unique single-turn winding configuration, which can reduce the coil overhang, increase the power density and torque, and reduce the weight of the motor in conventional multi-turn motors. The proposed MSPMSM is studied by the finite element method (FEM) and compared to a conventional PMSM with the same geometry and PM usage. The performance comparison results under different load conditions show that the proposed MSPMSM has higher torque and power density than the conventional motor.

In order to evaluate the effect of inert powder on the ignition sensitivity of sucrose dust, this study investigated the effects of NaHCO3, NaCl, NH4H2PO4 and Al(OH)3 on the minimum ignition energy (MIE) of sucrose dust. The results showed that all four different inert powders inhibited the MIE of sucrose dust, and all of them showed a trend that the smaller the particle size of the inert powders, the better the inhibition effect. The inhibition effect was ranked as NaHCO3 > NH4H2PO4 > NaCl > Al(OH)3. NaHCO3 and NH4H2PO4 had both physical and chemical inhibition effects, which were better compared to NaCl and Al(OH)3, which had only physical inhibition effects. Analysis of the flame images showed that the inert powder slowed down the combustion of the sucrose dust flame and reduced the flame height. No flame appeared in the region of higher inert powder concentration.

To study the influence of filling step and advancing distance on the deformation and failure of a working face floor, a mechanical model based on elastic foundation beam theory is established. The deflection and bending moment curves of the floor under different filling steps and advancing distance are obtained by Maple. Then, a fluid−solid coupling model of paste-filling mining on confined water is established by FLAC3D. The effects of different filling steps and advancing distance on the floor displacement, stress, and plastic zone of the floor are analyzed. The results show that there is a “concave” quadratic relationship between the filling step and the maximum displacement of the floor, and there is a “convex” quadratic relationship between the advancing distance and the maximum displacement of the floor. The maximum stress of the floor increases linearly with the increase in filling distance and tends to be stable with the increase in advancing distance. Moreover, the increase in... [more]

Jet velocity is an important parameter affecting the air entrainment rate of plunging liquid jet processes. While the vast majority of researchers have investigated the effect of jet velocity, only a few of them considered the effect of jet length in calculating the jet velocity at impingement point. This study investigates the difference (ΔV) between the jet velocity at the inception of the nozzle (Vj) and the impingement point (VL) for a range of operating conditions. Furthermore, bubble voidage inside the downcomer, another critical parameter in plunging jets, is estimated using three different voidage equations incorporated inside a momentum balance model to predict the two-phase elevation level (HR) inside the downcomer. Results showed that ΔV is significant (VL > Vj), especially at low jet flow rates and high jet lengths. Generally, the momentum balance model predicted the HR well, and its prediction improves with downcomer diameter. Given that, the model still needs to be refine... [more]

This silicon purification research work has two stages and results will be provided in two articles due to the large scope of work. This paper provides the results of the first stage, concerning the metallurgical silicon purification. Silicon was purified by a combined method consisting of slag refining with new slag composition and acid leaching. In the first phase, the metallurgical grade silicon produced by the classical carbothermic reduction method was investigated. In the second phase, the metallurgical purification by slag refining was completed using slags of various new compositions. The purified silicon samples obtained after the melting processes were analyzed for concentrations of impurities. Finally, acid leaching treatment of the obtained silicon was done, followed by elemental analysis of purified silicon. According to our experience we can determine that obtained silicon purity is adequate for further stages of planned study.

The three-phase flow in a aeration tank driven by an inverted umbrella aerator is relatively complex, including the processes of the hydraulic jump, air entrainment, and sludge particle sedimentation. A three-phase flow test bench for an inverted umbrella aerator is established for studying its influence on aeration performance. The experiment mainly studies the changed law of aeration performance under different immersion depths or sludge concentrations and measures the flow rate and sludge concentrations in the aeration tank in different working conditions. The results are as follows. (1) The total oxygen transfer coefficient, standard oxygenation capacity, and standard power efficiency increase with the increase in rotational speed. The total oxygen transfer coefficient and standard-charge oxygen capacity first increase and then decrease with the decrease in immersion depth, reaching a maximum at −20 mm immersion depth. The standard dynamic efficiency has a similar trend and reaches... [more]

The multiphase flow in the mold has a significant impact on the surface quality of the slab. In this paper, the multiphase flow in the mold is studied by establishing a one-quarter scale water mold, with the aid of a high-speed camera and particle image velocimetry (PIV). The oil phase will make the liquid surface velocity around the nozzle smaller. The greater the viscosity of the oil, the greater the critical water model casting speed and the shallower the critical immersion depth of submerged entry nozzle (SEN). Blowing will enhance the turbulence of the flow field in the mold and have a suppressing effect on the surface velocity. However, the vertical velocity of the narrow surface does not change significantly. The randomness of the bubble entering the mold from the nozzle can easily cause asymmetry of the instantaneous flow. The number of bubbles with a diameter less than 1 mm increase with the increase in gas flow rate. The larger the bubble size, the more buoyant around the noz... [more]

The drag coefficient CD plays an important role in studying the interaction forces between individual particles and fluid. Due to the irregular particle shape of natural sands, studying the sedimentation characteristics and drag coefficient model of irregular particles is of great significance in explaining natural phenomena, predicting the sedimentation process, and calculating the interphase forces between individual particles and fluid. In this paper, firstly, an experimental system for measuring the settling velocity was built, the settling velocity of 67 tests of spheres with different particle Reynolds number Res in the Newtonian fluid were obtained, and the CD−Res correlation of sphere settling in the Newtonian fluid was established. The proposed CD−Res correlation was in good agreement with the existing classical CD−Res correlations, which proves the reliability of the experimental system and data processing method. Existing literature shows that the previous models are only su... [more]

Cardiopulmonary resuscitation (CPR) is an emergency procedure performed on a person experiencing cardiac arrest to manually preserve brain function until spontaneous breathing and blood circulation can be restored. If performed timely and properly, it can improve the survival rate of a person experiencing cardiac arrest. The promotion of CPR has always been an important task for countries around the world. Countries around the world often hold relevant study camps and seminars to improve the public’s awareness of CPR. On the basis of this rationale, this paper proposes an interactive teaching aid kit for CPR that uses a CPR manikin and tutoring software to facilitate CPR learning among trainees. The CPR manikin is equipped with sensors that determine whether the CPR steps are performed correctly. Data from the sensors are sent to the tutoring software through wireless transmission. The software provides video demonstrations and textual instructions concerning the standard CPR procedure... [more]

A transiting test using vehicle-driving passive wind is a novel experimental technique to perform aerodynamic tests, proposed by the authors. However, this low-cost, short-cycle, and symmetrical test method can be influenced by many factors. In this paper, a comparative study on the influence of road types on a transiting test of aerodynamic coefficient measurements is presented. The tests were carried out on three different roads (expressway, viaduct highway, and tunnel highway); for each road type, structure models with and without end plates were investigated. For all the road types, measured turbulence intensity (around 4%) was similar to that of the wind tunnel test under the following conditions: 3 °C temperature, 42% humidity, 0.28 m/s natural wind speed, vehicle driving in a straight line with stable speed, and no traffic flow. All the tests were conducted under the above conditions. To deal with the interference components in the original data signals obtained from a viaduct h... [more]

SLAM algorithms generally use the last system posture to estimate its current posture. Errors in the previous estimations can build up and cause significant drift accumulation. This accumulation of error leads to the bias of choosing accuracy over robustness. On the contrary, sensors like GPS do not accumulate errors. But the noise distribution in the readings makes it difficult to apply in high-frequency SLAM systems. This paper presents an approach which uses the advantage of both tightly-coupled SLAM systems and highly robust absolute positioning systems to improve the robustness and accuracy of a SLAM process. The proposed method uses a spare reference trajectory frame to measure the trajectory of the targeted robotic system and use it to recover the system posture during the mapping process. This helps the robotic system to reduce its accumulated error and able the system to recover from major mapping failures. While the correction process happens whenever a gap is detected betwee... [more]

Deep eutectic solvents (DESs) have been used for the pretreatment of lignocellulose and showed selective dissolution for different lignocellulosic components. In this study, six new ternary DESs were synthesized on the basis of anhydrous oxalic acid DES by adding alcohol, acid, and deionized water, respectively, including choline chloride/anhydrous oxalic acid/ethylene glycol (ChCl-OA-EG), choline chloride/anhydrous oxalic acid/glycerol (ChCl-OA-G), choline chloride/anhydrous oxalic acid/lactic acid (ChCl-OA-LA), choline chloride/anhydrous oxalic acid/malonic acid (ChCl-OA-MA), choline chloride/anhydrous oxalic acid/10% H2O (v/v) (ChCl-OA + 10% H2O), and choline chloride/anhydrous oxalic acid/20% H2O (v/v) (ChCl-OA + 20% H2O). The lignin in bagasse was extracted and separated with these ternary DESs, and Fourier Transform Infrared (FTIR), Scanning electron microscope (SEM), X-ray diffraction (XRD), Two-dimensional Heteronuclear Single Quantum Coherence (2D HSQC), and Thermogravimetric... [more]

The motion of non-spherical particles with sharp edges, as they are commonly involved in practice, was characterized by residence time distribution (RTD) measurement in a continuous drum. Particles with two sizes, 6 and 10 mm, and two densities, 750 and 2085 kg/m3, were used in the experiments. The effects of rotation speed (3−11 rpm), incline angle (2−4°), feed rate, and mixture composition were investigated and compared to the results of other researchers on particles without sharp edges. We also fitted the RTD with an axial dispersion model to obtain a better insight into the flow behavior. MRT of non-spherical particles with sharp edges depends on ω−α similar to other shapes, while the value of alpha is higher for particles with sharp edges (0.9 < α < 1.24), especially at high incline angles. The MRT depends on incline angle, β−b, where b varies between 0.81 (at low ω) and 1.34 (at high ω), while it is close to 1 for other shapes. Feed rate has a slight effect on the MRT of p... [more]

The collective behavior of quantum particles is one of the most intriguing phenomena in quantum optics. In particular, superradiance refers to spontaneous collective emissions from a group of quantum particles behaving collectively as a whole due to the buildup of macroscopic quantum coherence. An important question is whether macroscopic quantum coherence is constructed by means of a quantum synchronization (i.e., a quantum analog of classical synchronization) or not. The purpose of this article is to draw attention to this question from the author’s perspective. A few selected studies relevant to synchronized atoms and molecules are discussed. The author concludes that collective behaviors of quantum particles may be formulated as quantum synchronizations, but extensive studies are still needed to confirm this hypothesis.

In order to dispose of large quantities of mineral tailings, paste backfill is proposed and widely adopted. Paste backfill, which has high concentration and yield stress and behaves as a non-Newtonian fluid, is prepared at the surface plant and then transported underground. Vertical pipelines are more likely to suffer various failures, such as pipe breaks, wear and plugging, during the transport process. Few present studies focus on the flow behavior of paste slurry flowing in vertical pipes. In this work, two L-shaped pipeline systems with internal diameters (ID) of 40 mm and 65 mm with electrical resistance tomography (ERT) were manufactured to visualize flow regimes and measure the axial velocity and pipe pressure of slurry flowing in the upper and lower zones of vertical pipes. Flow regimes were extracted from ERT-reconstructed images stacked by time-series. Based on this, four typical flow regimes were summarized, and the characteristics of velocity and pressure change with vertic... [more]

This article mainly considers the coexistence of physical sales channels and online sales channels. Online retailers with online sales channels consider whether to provide return policies and whether to provide consumers with return insurance. The research established four return strategy models that: do not provide returns; provide returns but do not provide return insurance; provide return insurance, but the cost is borne by online retailers; and provide return insurance, but the cost is borne by consumers. The authors then studied the online retailers’ optimal return and shipping insurance selection strategies. The results show that when the proportion of residual return value after the value reduction of unit returned products was large, online retailers set higher sales prices and provided return policies, while offline retailers needed to reduce sales prices in order to attract more consumers. When the consumer unit product return compensation was relatively large, online retaile... [more]

The aim of this article is to determine the effect of the biaxial loading of a car seat, in vertical and horizontal directions, on seating comfort. We measured the transfer characteristic in the vertical direction with a free load. The method of laboratory testing of the car seat was chosen due to the simple repetition of the tests, ensuring the same test conditions, with high accuracy of their reproduction. To determine the effect, tests with uniaxial loading were compared with tests with biaxial loading. The resulting characteristic was the transfer characteristic in the vertical direction. The effect of horizontal loading on the transfer characteristic of a car seat was determined.

Understanding chemical processes at the single-molecule scale represents the ultimate limit of analytical chemistry. Single-molecule detection techniques allow one to reveal the detailed dynamics and kinetics of a chemical reaction with unprecedented accuracy. It has also enabled the discoveries of new reaction pathways or intermediates/transition states that are inaccessible in conventional ensemble experiments, which is critical to elucidating their intrinsic mechanisms. Thanks to the rapid development of single-molecule junction (SMJ) techniques, detecting chemical reactions via monitoring the electrical current through single molecules has received an increasing amount of attention and has witnessed tremendous advances in recent years. Research efforts in this direction have opened a new route for probing chemical and physical processes with single-molecule precision. This review presents detailed advancements in probing single-molecule chemical reactions using SMJ techniques. We s... [more]

Using the MTS816 rock mechanics servo tester, an acoustic emission monitoring system and high-speed digital photographic equipment, uniaxial compression tests were conducted on granite specimens containing single fracture slabs after repeated treatment (treatment times 1, 5, 10, 15 and 20) with three types of high temperature (250, 350 and 450 °C) water cooling, respectively, to analyze the basic mechanical parameters, acoustic emission change characteristics and fracture evolution of the specimens during the uniaxial compression process. It is shown that the heating temperature and the number of treatments not only have a deteriorating effect on the basic mechanical parameters of the specimens but also have an important effect on the changes in the basic parameters of acoustic emission at different compression stages. At 250 °C, the acoustic emission characteristics of the specimens at the initial tightening stage tended to decrease (N = 1 and 5 times) then, increase (N = 10 and 15 ti... [more]

Liquid ammonia as a non-aqueous medium has many physical properties close to water, such as small molecular weight and strong permeability. It has been widely used for the ecological processing of cellulosic fibers to improve their luster, softness and dyeing properties. However, there are few reports on the dyeing of wool treated with liquid ammonia, especially at a lower temperature. Herein, a continuous liquid ammonia finishing machine was used to batch process wool followed by dyeing in a commonly-used wool dyeing machine. The results showed that many scale flakes and some cuticle cracking were seen on the fiber surface, and the disulfide bonds of cystine were broken down after liquid ammonia treatment, which promoted the diffusion of dyestuff into the fiber. Moreover, the uptakes and K/S value of wool dyed with Lanaset and Lanasol CE dyes were higher than the untreated wool, and the dyeing temperature could decrease to 85 °C, while the degree of fiber strength reduction merely dec... [more]

The adsorption pore structure is the key affecting the technology of enhanced coal bed methane recovery (ECBM). In this paper, nitrogen adsorption measurement (NAM) and low-field nuclear magnetic resonance (NMR) methods are used to test the structural parameters of adsorption pores of four coal samples with different metamorphic degrees. Combining with the fractal theory, the applicability and the physical significance of fractal dimensions obtained from different models are analyzed. Finally, the main factors affecting the complexity of the pore size structure and the influence of fractal characteristics on the adsorption properties of coal are discussed. The results show that with the increase in the degree of metamorphism, the ranking order of the volume and the specific surface area of adsorption pores of four coal samples are long flame coal > anthracite > gas coal > coking coal. The fractal dimension D2 calculated by the Frenkel−Halsey−Hill (FHH) fractal model ranges from 2.5 to... [more]

This paper investigates the effects of the machining process on the thrust force and mechanical characteristics for the direct drive feed system driven by the flat permanent magnet synchronous linear motor (PMSLM) in machine tools considering the electromechanical couplings. Firstly, the cutting force in the machining process is researched. Then, the analytical model of the direct drive feed system is established and analyzed. The electromechanical couplings between the mechanical system and servo system in the direct drive feed system are studied. Furthermore, the influences of the cutting force on different couplings are analyzed, and the thrust force characteristic is analytically represented. Finally, the validity of the theoretical analysis is verified by the experiments, and the effects of the machining process on the dynamic precision of the feed system are discussed. The results show that the electromechanical couplings in the direct drive system will aggravate the effects of t... [more]

This paper explains the project’s objectives, identifies the key stakeholders, defines the project manager’s authority and provides a preliminary breakdown of roles and responsibilities. For the project’s future, it acts as a source of authority. This paper’s objective is to record the justifications for starting the project, its goals, limitations, solution instructions and the names of the principal stakeholders. This manuscript is meant to be used as a “Project Management Plan Light” for small and medium-sized projects when it would be uneconomical to prepare an entire collection of documents that make up a project management plan. A global media cloud will be provided and managed by the ABC cloud company inside of a consumer’s current premises. In this paper, the authors explain the end-to-end delivery of cloud and compute services. The article mainly focuses on the delivery of virtual machines (VMs), graphics processing unit (GPUs), cloud storage, transcoding, packaging, 24/7 cust... [more]

A growing demand for cheap, strong, and lightweight structures has resulted in an increasing need for materials incorporating macroscopic structures such as surface textures in the form of dimples or internal non-uniformities such as porosity. This has highlighted the potential for misleading results when applying the current standards for the determination of yield strength to materials incorporating such non-uniformities. In the present study, discontinuous, continuous, and severely continuous (departure from linearity significantly prior to macroscopic yield) yield behaviours during tensile loading have been explored with respect to the determination of yield strength. This has clearly shown the limitations of standard measures as well as the incompatibility of different measures, making the comparison of yield strengths deceptive. Therefore, a novel derivative yield method has been proposed. Based on the second derivative of stress with respect to strain, this method is independent... [more]