Pole Arrangement Research Articles

A hybrid harvester using a magnetically coupled pendulum structure for limb movement

ABSTRACT Energy harvesting and conversion devices can provide power solutions for wearable devices. In this paper, a piezo-electromagnetic hybrid energy harvester (PEMHEH) using a magnetically-coupled pendulum structure for low-frequency limb movement is proposed. PEMHEH consists of a piezoelectric generator (PEG) unit including a main piezoelectric transducer, an auxiliary piezoelectric transducer (APT), and an electromagnetic generator (EMG) unit. It can reduce the starting frequency and increase the output performance by adopting a slidable mass block, the APT, and the rational magnetic pole arrangement. Its theoretical model is established, and magnetic simulation and experimental tests are carried out. The results show it can be started at 0.4 Hz excitation, and the output performance is maximized at 2 Hz. The maximum voltages of the piezoelectric generator and electromagnetic generator units are 5.29 V and 457 mV, and the maximum power is 286.16 μW (30 kΩ) and 11.25 μW (2 kΩ). The PEMHEH can light up LED boards at a 1 Hz excitation frequency. It has the potential to power wearable devices.

An analysis of parameters affecting ampacity in aircraft bipolar MVDC power cables via coupled electrical, thermal, and computational fluid dynamic modelling

AbstractThe next generation of aircraft, including more electric aircraft and all‐electric aircraft, require electric power systems with high power density and low system mass specifications. Increasing the voltage of the system to the range of a few kV, medium voltage (MV), is a reasonable approach to achieving high‐power‐density and low‐system‐mass EPSs for aircraft applications. Higher voltages, however, pose many challenges for aviation MV power cables such as arcs and arc tracking, partial discharges (PDs), and thermal management. In this regard, thermal management is more challenging since heat transfer by convection is greatly reduced at wide‐body aircraft's cruising altitudes due to the reduced air pressure. In this paper, a finite element method (FEM) model is developed in COMSOL Multiphysics for an aircraft bipolar MVDC (±5 kV) power cable. Using the model, the maximum permissible cable current at a low pressure of 18.8 kPa (at an altitude of 12.2 km from sea level, the usual cruising altitude for wide‐body aircraft) is calculated. Also, an analytical model is developed based on analytical and proven empirical correlations governing conductive, radiative, and convective heat transfers at the steady state to estimate the ampacity of the bipolar cable system at reduced pressure. It was shown that the proposed analytical model can be used for atmospheric pressure and systems with a larger number of poles, expanding its range of applications. The results of the FEM and analytical models correlate at wide ranges of parameters such as ambient temperature, duct size, distance between the positive and negative pole cables, and the overall diameter of the cables. The influence of horizontal and vertical arrangement of poles is included in the analytical model. The results of this study can be used to design bipolar MVDC power cable systems for the envisaged wide‐body AEA.

Design and evaluation of a monostable symmetric piezoelectric energy harvester based on cantilever structure and magnetic excitation action.

This work proposes a monostable symmetric piezoelectric energy harvester based on the cantilever structure and magnetic excitation action (M-PEH). The governing equations of M-PEH are derived based on its kinematic properties. The intrinsic frequency of the piezoelectric cantilever beam was obtained by modal simulation. It has been demonstrated that the mode of arrangement of the magnetic poles has a significant effect on the output voltage of the energy harvester. The proposed M-PEH has four driving magnets with a mass of 6g and a radial driving distance of 15mm for more efficient energy harvesting. The experimental results show that the maximum voltage of the M-PEH with the double U-type rotor was 31.2V at 240rpm and 110 kΩ external resistance. The average power of the PEH with the double U-type rotor was 16.562 mW at a speed of 240rpm with an outer resistance of 20 kΩ. The energy harvester with a double U-type rotor can realize a voltage output of not less than 10V in the range of 60-300rpm when the same poles of the tip magnets are arranged outward. The M-PEH can also easily light up LEDs or miniature electronic watches with speeds of 120rpm and 240rpm. This further proves that the proposed piezoelectric energy harvester (M-PEH) has a better energy harvesting effect and great potential for practical applications.

An Optimal Choice of Characteristic Polynomial Roots for Pole Placement Control Design

The problem of finding the arrangement of closed-loop control system poles that minimizes an objective function is considered. The system optimality criterion is the value of the H∞ norm of the frequency transfer function relative to the disturbance with constraints imposed on the system pole placement and the values of the H∞ norm of the sensitivity function and the transfer function from measurement noise to control. An optimization problem is formulated as follows: the vector of variables consists of the characteristic polynomial roots of the closed loop system with the admissible values restricted to a given pole placement region; in addition to the optimality criterion, the objective function includes penalty elements for other constraints. It is proposed to use a logarithmic scale for the moduli of the characteristic polynomial roots as elements of the vector of variables. The multi-extremality problem of the objective function is solved using the multiple start procedure. A coordinate descent modification with a pair of coordinates varied simultaneously is used for search.

Toward Onboard Proportional Control of Multi-Chamber Soft Pneumatic Robots: A Magnetorheological Elastomer Valve Array.

Soft pneumatic actuators (SPAs) are commonly used in various applications because of their structural compliance, low cost, ease of manufacture, high adaptability, and safe human-robot interaction. The traditional approach for achieving proportional control of soft pneumatic robots requires the use of industrial proportional valves or syringe drivers, which are not only rigid and bulky but also hard to be integrated into the body of soft robots. In our previous research, we developed a Magnetorheological elastomer (MRE)-based soft valve that showed advantages for controlling SPAs due to its compliance, compactness, robustness, and compatibility for continuous pressure modulation. Modern soft robots with multiple chambers require more MRE valves onboard for their control. However, merely packing more MRE valves for soft robots can cause problems like magnetic interference, flow rate deviation, and overheating. Therefore, in this study, we proposed a two-dimensional MRE valve array design to solve issues of magnetic interference and overheating when expanding from a single MRE proportional valve into an integrated array. The magnetic interference and the overheating problem were investigated through multiphysics simulation, bringing the optimal choice of valve spacing (1.2 times the single valve diameter), magnetic coil pole arrangement (same pole), and the cooling system design (internal cooling chamber with flowing water). Physical experiments showed that our MRE valve array maintained its original flowrate performance with low magnetic interference (0.89 mT) and low coil temperature (under 73.9°C for 5 min).

Proliferation and Arrangement of Poly(vinylidene fluoride) Oval γ Single Crystals Grown in Its Poly(1,4-butylene adipate) Blends

Proliferation and Arrangement of Poly(vinylidene fluoride) Oval γ Single Crystals Grown in Its Poly(1,4-butylene adipate) Blends

Surface polishing of CoCrMo alloy by magnetorheological polishing

Improving the surface quality of biomedical alloys is of great practical significance to the evolution of orthopaedic implant surgery. In the polishing stage, traditional polishing methods are prone to problems, such as substandard surface roughness values and poor surface morphology, which severely affect the service life of materials. The surface quality of the CoCrMo alloy treated with magnetorheological polishing was studied. First, a polishing tool was designed based on magnetic field simulations of different magnetic pole arrangements and flow field simulations of the shear behaviour of the magnetorheological polishing cluster. Second, to improve the surface quality, an equally spaced pseudo-random path was planned, and the polishing effect for this path was verified using simulations and experiments. Moreover, the effect of different process parameters, i.e., the machining gap, polishing tool rotation speed, and abrasive particle size, on the polishing forces and the surface roughness values was studied. Finally, the wettability of the modified surface of the CoCrMo alloy after polishing was tested. The results confirm the ability of magnetorheological polishing to improve the surface quality of CoCrMo alloys, which has a certain guiding significance for the development of advanced biomedical implants.

Carbide twist drill surface polishing and cutting edge passivating based on magnetic field-assisted shear thickening

The multi-field compound polishing method based on the shear thickening has been applied to the processing of various hard materials due to its characteristics of low damage and adaptability to complex surface shapes. The surface defects on the carbide twist drill are usually produced during the grinding. This paper proposes a magnetic field-assisted shear thickening polishing (MASTP) method based on shear thickening and pumping effect, aiming to enhance surface quality of twist drill and passivate cutting edges to improve its cutting performance. The microscopic material removal mechanism of the twist drill and the rheological properties of magnetic shear thickening fluid were analyzed. The magnetic field intensity distribution in the polishing area for two types of magnetic pole arrangements is simulated. A numerical simulation was used to investigate the effect regularity of the polishing gap and spindle speed on the flow field shear stress. Experimental validation was carried out based on the processing platform. The results show the effects of processing parameters on twist drill surface roughness improvement rate and edge radius correspond to the simulated shear stress. After 60 min of polishing, the surface roughness improvement rate reached 94.7% and 80.4% at the body clearance and margin of the twist drill, respectively. The passivating radius of the major cutting edge can reach 12.92 μm, while the passivating radius of the minor cutting edge can reach 15.73 μm. At the same time, the edge defects caused by the grinding are also removed.

Techno-Economic and Social Aspects of Smart Street Lighting for Small Cities – A Case Study

This work proposes and develops a holistic framework for intelligent roadway lighting in largely ignored small cities using an unlit 1.1-mile section of Harney Street in Laramie, Wyoming, United States as a case study. The novel framework includes a technical analysis, an economic evaluation, and a public survey. Following the technical analysis, 21 streetlight units in a staggered pole arrangement are recommended to optimize illuminance levels for the minor arterial road as commonly found in cities like Laramie. Two energy source options are considered – a grid-only option and a hybrid option that utilizes solar power for lighting and grid electricity for electric vehicle (EV) charging. The economic and social aspects of this study reveal the need for public-private partnerships to fund smart street lighting projects in small cities. From a benefit-cost analysis standpoint, the grid-only option is currently more economically feasible; however, most residents prefer the hybrid system. Additional capabilities like EV charging, air quality monitoring, and weather sensing provide unique economic and social benefits for both residents and city authorities. This work provides a veritable framework that both private and public stakeholders can adopt for future implementation of smart street lighting projects in contemporary low-population towns and cities.

Effects of particle size on the separation efficiency in a rotary-drum eddy current separator

Eddy current separation is a technology for recovering non-ferrous metals. The influence of particle size on the separation is of significant importance due to the variety of materials. It was investigated by combining simulations and physical experiments. A strong correlation between the simulation and the experiment was found by Pearson correlation analysis. Then the interaction effects between the particle size and the material type, rotational speed, magnetic pole arrangement were investigated. It shows that an optimal particle size exists for a specific condition, and the separation efficiency of fine particles can be improved by increasing rotational speed, magnetic pole number, and the electrical conductivity/density of material, as well as utilizing torque of Lorentz force. The underlying mechanism of particle size affecting separation was discovered by analyzing eddy current distribution and field gradient. These results provide insight into the design and optimization of eddy current separation for particles of various sizes. • The correlation between simulation and physical experiment was established. • There is an optimal particle size for separation under a specific condition. • The rotation of the particles increases with the decrease of the particle size. • The magnitude and distribution of eddy current is related to the particle size. • Some optimization principles of the eddy current separator were proposed.

Development of An Analytical Method for Design of Electromagnetic Energy Harvesters with Planar Magnetic Arrays

In this paper, an analytical method is proposed for the modeling of electromagnetic energy harvesters (EMEH) with planar arrays of permanent magnets. It is shown that the proposed method can accurately simulate the generation of electrical power in an EMEH from the vibration of a bridge subjected to traffic loading. The EMEH consists of two parallel planar arrays of 5 by 5 small cubic permanent magnets (PMs) that are firmly attached to a solid aluminum base plate, and a thick rectangular copper coil that is connected to the base plate through a set of four springs. The coil can move relative to the two magnetic arrays when the base plate is subjected to an external excitation caused by the vehicles passing over the bridge. The proposed analytical model is used to formulize the magnetic interaction between the magnetic arrays and the moving coil and the electromechanical coupling between both the electrical and mechanical domains of the EMEH. A finite element model is developed to verify the accuracy of the proposed analytical model to compute the magnetic force acting on the coil. The analytical model is then used to conduct a parametric study on the magnetic arrays to optimize the arrangement of the PM poles, thereby maximize the electrical power outputted from the EMEH. The results of parametric analysis using the proposed analytical method show that the EMEH, under the resonant condition, can deliver an average electrical power as large as 500 mW when the PM poles are arranged alternately along the direction of vibration for a peak base acceleration of 0.1 g. A proof-of-concept prototype of the EMEH is fabricated to test its performance for a given arrangement of PMs subjected to vibration in both the lab and field environments.

Improvement of trapping performance of magnetic particles by magnetic multi-poles via Brownian dynamics simulations of magnetic rod-like particles in a Hagen-Poiseuille flow

In the present study we have implemented a Brownian dynamics simulation of a Hagen-Poiseuille flow in a cylindrical vessel and have investigated the feasibility of multi-pairs of magnetic poles for exhibiting a good particle trapping performance. We have focused on two representative types of configuration consisting of two pairs of magnetic poles. The first is a vertical configuration of two pairs of poles arranged perpendicular to the direction of the flow field. The second is a parallel configuration, where each pair of magnetic poles is arranged along the surface of the vessel wall. In the case of the vertical pole arrangement, although densely-packed aggregates were formed between the poles, their location was unstable in the flow field and they tended to be carried away downstream. In contrast, a densely-packed cluster formed in the parallel arrangement tended locate in a more stable manner along the surface of the wall where the flow field is weaker. We conclude that under appropriate conditions of the magnetic particle-particle interaction strength, the applied magnetic field strength and the pole separation distance, the parallel arrangement of magnetic poles is the configuration of choice for giving rise to a superior trapping performance.

Simulations and Analysis of the Optimum Uniformity for Pedestrian Road Lighting Focusing on Energy Performance and Spill Light in the Roadside Environment

Road lighting uniformity is an essential lighting quality parameter for motorists and pedestrians and varies with lighting design parameters. Increased road lighting uniformity may result in benefits, such as increased reassurance and perceived safety for pedestrians or an increased overall visual perception. However, no previous study has investigated how road lighting uniformity varies with lighting design scenarios or how the uniformity of various lighting design scenarios affects other essential parameters, such as energy performance and obtrusive light. This study aimed to investigate: (I) how uniformity varies with different road lighting design scenarios, and (II) how uniformity correlates with energy performance and risk for increasing spill light. The study is limited to pedestrian roads. We performed photometric calculations in ReluxDesktop for more than 1.5 million cases with single-sided pole arrangements and for various geometries of road width, pole distance, pole height, overhang, and luminaire tilt. The results were analyzed with a set of five relevant metrics that were calculated and analyzed together with uniformity. For the evaluation, we used the minimum luminaire power needed to achieve an average illuminance of 10 lx, the power density indicator (DP), edge illuminance ratio (REI), and we introduced two new indicators for spill light on the ground in the border areas: the extended edge illuminance ratio (extended REI) and the spill flux ratio (RSF). The results show that increased uniformity levels may significantly increase energy consumption and spill light, but that both these impacts can be relatively controlled if uniformity is kept under certain limits. The investigated cases also demonstrated that improper lighting planning significantly increases adverse effects, such as spill light.

Parametric Study of Eddy Current Brakes for Small-Scale Household Wind Turbine Systems

The design and application of eddy current brakes (ECBs) should be simple; further, ECBs should be used semi-permanently. This study aimed to determine major parameters for designing an ECB that can be applied to a small-scale wind turbine generator. To this end, an ECB was developed that could actuate without additional power, thus improving the efficiency of the generator. A series of simulations were conducted for a parametric study to pre-design ECBs suitable for small wind turbines. The six parameters chosen were disk thickness, number of magnets, radial location of magnets from center of disk, magnet pole arrangement, magnetic flux density, and rotational speed. The simulations were conducted on COMSOL Multiphysics. The results indicated that the number of magnets and magnet pole arrangements can significantly affect the performance curve of ECBs. Moreover, the disk thickness and rotational speed are linearly proportional to the braking torque.

Catalytic Activity Enhancement of Cu-Zn-Based Catalyst for Methanol Steam Reforming with Magnetic Inducement

Magnetic inducement was applied during metal loading to enhance Cu-Zn catalysts for methanol steam reforming in the temperature range of 200–300 °C. The supports used in this study were the γ-Al2O3 support and CeO2-Al2O3 supports prepared under different magnetic environments. Cu-Zn loading between the north and south poles (N-S) on the CeO2-Al2O3 support, prepared between two north poles (N-N), led to the highest H2 production at 300 °C (2796 ± 76 µmol/min), which is triple that of Cu-Zn/CeO2-Al2O3 prepared without magnetic inducement and ~11-fold the activity of the Cu-Zn/Al2O3 reference catalyst. The N-S magnetic environment during metal loading leads to lower reduction temperatures and larger Cu(1+):Cu(2+) ratio. These results showed that the pole arrangement of magnets during metal loading could affect the catalytic activity of the Cu-Zn catalyst owing to its influence on the reducibility and the oxidation state of Cu active metal.

Efficient Power Response Characteristics of 2KVA Low Cost Inverter under Resistive Loads and Inductive Loads

The paper discussed the design of low cost inverter using SG3525A IC and IRF3205 MOSFET in H-Bridge configuration. The implementation of the real construction involved the use of IC SG3525A for generation of output pulses; the totem pole arrangement of transistors was used in the driver section of the inverter to boost signals as well as switching purposes. The H-bridge configuration was employed to effectively switch the four MOSFETs, this switching produced an alternating potential of 220V. Pre-set conditions such as load condition, low battery cut, overcharge cut and constant output were set at 1700W, 10V, 13.3V and 220V respectively so as to ensure effective and long lasting usage of the inverter. The battery used for the operation of the inverter was 12V maintenance free battery in order to reduce the cost of using the inverter. The various tests carried out on this inverter were tests on inductive loads, resistive loads, home appliances, overload condition, low battery and charging control. The aim of this work is to achieve inverter design analysis under resistive loads and inductive loads for efficient power usage at lowest possible cost. This was achieved by connecting various resistive and inductive loads on the inverter. The results show that the system can operate under both the resistive and inductive loads but operates better under resistive loads, the reason for this is that inductive loads always draw large currents during start-ups which always result to power losses.
 Graphs were plotted and analyzed; the results also showed that this inverter can take up to 1700W of resistive load and inductive load of 1020W. The inverter produced no humming sound from inductive loads and home appliances such as fan, television, refrigerator e.t.c that were within its maximum capacity of 1700W.

Research of Turbine Efficiency Test by Current-Meter Method in Circular Pipe

For absolute discharge and efficiency measurement of turbine with medium and low water head, the current-meter method has high precision, good reliability, and wide application range. For rectangle flow channel, it is easy to lift down a gate frame with current meters to measure the flow velocity, but for circular pipe, due to the high stress, possible deformation, and strict safety requirement, the design, installation, and implementation of the support bracket is the key to the measurement by current-meter method. In this paper, we made the research of key technology for current-meter method in circular pipe. By building a numerical model for circular pressure pipe and flow measuring bracket, we analysed the influence of meters arrangement, the force and deformation of support pole with CFD, and fluid-solid coupling method, Finally, an optimized reinforcement bracket is proposed, with combined smooth and stress calculation, the measuring bracket is verified it can withstand the flow stress and has good safety characteristics, which can provide a reference for other similar turbine efficiency tests.

The effect of nuclear radiation on mutation chromosomes of shallot cells (Allium cepa)

Environmental pollution by nuclear radiation has been known to endanger chromosomes. This research aims to analyze the abnormal forms of root shallot chromosomes which are irradiated by nuclear with various levels of radiation. This is a quasi-experimental research. The treatment group was given radiation through nuclear reactors at a dose of 11.88 rad, 8.69 rad, 2.01 rad, 1.28 rad, 1.15 rad, 0.26 rad, 0.00034 rad, 0.00016 rad, while the control group was without radiation. The staining of the preparations was carried out using Acetocarmine 2%. Reading preparations using a microscope with a magnification of 400x. The results of the study showed the emergence of various forms of chromosomal abnormalities. Abnormal forms that appear are pole to pole arrangement chromosome, unequal separation, binucleate cell, pulverized ball metaphase, sticky anaphase with broken bridge, chromosome rosette, abnormal chromosome fragment, early cell plate formation at late anaphase, sticky metaphase, binucleate cell with a bridge, chromosome fragments, binucleate cells, chromosome gaps, ball anaphases with a diagonal scattered anaphase bridge, and aberrant grouping at anaphases in a giant cell. The novelty of this preliminary study is that chromosomal abnormalities in the onion roots were found even in the very low radiation group. Large-scale research is required and their effects if eaten by animals or humans need further research.

Perancangan Dan Penataan Penerangan Jalan Umum Dengan Aplikasi Dialux evo 8.2 Di Jalan Depok Cilodong

The increase in population, urban development and road construction are the demands of many communities in obtaining public street lighting for road users by providing better services. Public street lighting has become a necessity for many people, which is very important for two-wheeled, four-wheeled, and many-wheeled drivers for safety and comfort in traffic, especially at night. Therefore, the authors conducted a new research design by arranging public street lighting in the area of ​​the Depok Cilodong highway, with the aim of providing the beauty of the road environment by the model of the arrangement and installation of poles, pole height and PJU lamp models to the road body. Its uniqueness is seen from the perspective of the side of social and environmental impacts that are generally not seen by the local government and the level of evenness of road lighting on road materials is still lacking, so that the impact on the road user community is better and more modern. The method used with the Dialux EVO 8.2 Program for short road lengths can choose street lights taken from the IES Lighting data on the 10W Eco Led, 10 VAC Milky Way, which is installed with a height of 8 meters with a distance between poles 15 meters with a large amount of procurement allows for high costs. For the long distance of the road, you can use the 20W Led Bimasakti Eco street light, 10 VAC, which is installed with a height of 8 meters and 20 meters between the poles. So by analyzing the selection criteria, it is capable of producing street lighting with lighting levels in accordance with SNI 7391-2008 and considering the quantity of material procurement as well as the tipping point which has an impact on financing for installation services.
 
 

Separation of Polarizations Using Shifted Electrode Arrangement in Proton Exchange Membrane Water Electrolysis

Proton exchange membrane water electrolysis (PEMWE) has attracted much attention because of its advantages such as the ability to downsize the equipment and produce high-purity hydrogen. For further improvement of the efficiency and durability of PEMWE, it is necessary to separate and examine polarizations. However, it is difficult to separate the anodic and cathodic polarizations by the AC impedance method. Also, it is difficult to separate resistance polarizations by using the reference poles with normal electrodes as shown in Figure 1 (a). Therefore, we are developing a device in which the electrode arrangement of both poles is deliberately shifted and a reference electrode is placed on each of the anode and cathode, as shown in Figure 1 (a) [1]. Since the phenomena in PEMWE are complicated due to the mutual influence of material/electric charge transport and reaction distribution, a multiphysical numerical analysis considering the potential distribution in the shifted electrode structure have been performed using COMSOL Multiphysics 5.4. Ohm's law was solved for the ionic charge transport in the electrolyte and the ionomer of the catalyst layer and also applied to the contact resistance between the electrode and the current collector. Butler-Volmer's equation was used for the activation overpotential at both poles. Figure 1(b) shows the electrolyte potential distribution when the electrode arrangement is shifted, and the potential distribution was completely changed from the (a). Figure 2 shows the relationship between the shift amount of electrode and the potential difference between both reference electrodes. The potential difference between both reference electrodes increases as the shift amount of electrode increases, and the rate of change of the potential difference decreases as the shift amount increases. Design and data processing based on these numerical results will lead to the development of devices that can perform more accurate separation of polarizations.Reference1) S. Mitsushima, H. Kashiwagi, K.Nagasawa, and Y. Kuroda, ECS Meet. Abstr., MA2019-02, 1715 (2019). Figure 1