Low Speed Research Articles

Development and Implementation of Stop-and-Go Inertial Profiler Certification Procedure in California

The ride quality of a road in California is often determined by evaluating pavement smoothness using an inertial profiler (IP). Conventional IP technology, per California Test (CT) 387, requires IP operators to maintain a minimum speed of 15 mph to collect pavement-smoothness data. However, maintaining a minimum speed of 15 mph in busy urban areas or on hilly terrains can be difficult and unsafe, often requiring traffic control. Caltrans and industry have identified a new technology, the “Stop-and-Go” (SAG) IP, for collecting pavement-smoothness data at low speeds (under 15 mph) without traffic control. The previous version of CT 387 did not allow for the use of SAG IPs. To address this issue, the Pavement and Materials Partnering Committee (PMPC) evaluated SAG IP and updated CT 387. A certification procedure for SAG IP was developed, and included in CT 387, based on a series of runs using speed profiles under various braking and acceleration conditions simulating urban traffic conditions. Any SAG profiler can be certified if it meets the requirements of AASHTO R 56 and CT 387. The certification procedure was validated using qualification runs at the Caltrans certification track, along with field testing, demonstrating that SAG IPs provide similar results to conventional IPs. Based on the validation, along with the subsequent update of CT 387, the PMPC approved the implementation of SAG IPs for optional use by Caltrans and industry. These developments helped California become one of the first states to develop and implement a certification procedure for SAG IPs.

Association Between Disease Severity and Frailty in Patients with Aortic Stenosis.

Frailty is highly prevalent among patients with aortic stenosis (AS). Nonetheless, the impact of AS severity on frailty remains unclear. This study aimed to clarify the association between AS severity and frailty in this population.This retrospective study included consecutive patients with AS who were hospitalized as candidates for transcatheter aortic valve implantation (TAVI). The prevalence of frailty, N-terminal pro B-type natriuretic peptide (NT-proBNP) level, gait speed, and geriatric nutritional risk index (GNRI) were compared between patients with severe and those with very severe AS. We employed multiple logistic regression analysis to examine the association between AS severity and frailty.A total of 137 patients were included. The prevalence of frailty was not significantly different between the severe and very severe AS groups (31% versus 30%). Similarly, no significant differences between the groups were observed for gait speed and GNRI, whereas the NT-proBNP level was significantly higher in the very severe group than in the severe AS group (P < 0.01). In the multiple logistic regression analysis, AS severity was not associated with frailty; however, gait speed and GNRI showed significant association with frailty independently of age, sex, and heart failure (very severe AS: odds ratio [OR] 1.051, 95% confidence interval [CI] 0.439-2.517; low gait speed: OR 5.109, 95% CI 1.556-16.775; malnutrition: OR 2.841, 95% CI 1.145-7.049).These findings suggest that low-intensity exercise training and nutritional therapy may be necessary in addition to AS treatment for the management of frailty in this population.

Climatic Impact on the Air Pollutant Concentrations Emitted from Gas Stations in Fallujah, Al-Anbar, Western Iraq

The research investigates the influence of climatic elements like temperature, relative humidity, rainfall, evaporation, dust storms, wind direction, and speed on the air pollutant concentrations at gas stations in Fallujah city while examining their impact on humans and the environment. This was achieved by measuring concentrations of CO, NO2, and CH4, suspended particles (TSP, PM10), and Cu, and Pb. It was found that the impact increased in July compared to January, because of the influence of the measured climatic elements. Rising temperatures increase air pollutants' concentrations in the atmosphere, while winds spread them from emission sites to distant locations. Moreover, summer temperatures significantly impacted air pollutant concentrations at the study stations, particularly at Al-Rehab gas station, with the highest recorded temperatures of 48.4°C. Some gas stations also exceeded local environmental limits for TSP, PM10, CO, NO2, and Pb. The study revealed that summer temperatures with wind speeds of 2.1 m/s resulted in the highest air pollutants values, while winter temperatures with wind speeds of 1.9 m/s decreased these values. Higher temperatures increase chemical reactions and temperature inversions, leading to increased pollution concentrations and exacerbating air quality problems in the study area. Strong winds disperse pollutants, reducing concentration in the study area, while low wind speed increases concentrations and stagnation, resulting in poor air quality in the studied sites. The importance of the current study lies in evaluating pollutants in the Fallujah city, determining their causes, the extent of the impact, and contribution of natural and human sources in causing changes in air pollutant concentrations; caused by emission from the source. Moreover, the current study showed its impact on human’s health, and trying to find solutions to limit these effects or reduce their levels to ensure the safety of the environment and health.

Bend-twist adaptive control for flexible wind turbine blades: Principles and experimental validation

This study proposes a new methodology for optimizing the power curve of a wind turbine at low wind speeds. The principles of bend-twist coupling and the mechanism of energy exchange between the structure and inflow are analyzed. For the blade’s geometric nonlinearity, the virtual displacements and strain fields are described using the Green-Lagrange strain theorem, retaining third-order terms in the energy expressions. The equations of motion are derived using Hamilton’s principle. The bend-twist coupling effects and large deformations of the blade are analyzed using the Updated Lagrange method. Notably, the angle of attack for a single blade section is influenced by bend-twist deformation, causing variations in the rotor’s maximum power coefficient from its optimal value. Additionally, the projection length of the blade, influenced by centrifugal forces, also affects the bend-twist deformation. Based on these findings, an aero-elastic coupling control strategy, termed “Bend-twist Adaptive Control”, is proposed and validated through experiments. The results demonstrate that the proposed control strategy could increase annual power production by 2.3 %. These conclusions offer a promising outlook for future wind turbine blade design and power optimization.

ANALISIS POTENSI PEMBANGKIT LISTRIK TENAGA ANGIN DI TAMAN TEKNOLOGI TOWER TURYAPADA

Tower Turyapada is a technology concept tourism center with various attractions located in Pegayaman Hill, Singaraja and is programmed to meet Building Green Building (BGH) criteria. One component of the BGH assessment is the use of renewable energy. The use of renewable energy that is suitable to be utilized in this tower building is PLTB (Wind Power Plant), because it is located in a hilly area with strong winds. The potential of wind power plant has been analyzed using descriptive method through quantitative approach. Analysis of wind energy potential using primary data by taking direct measurements in the Turyapada Tower area in February - March and using secondary data from the I Gusti Ngurah Rai Meteorological Station, Badung Regency. The analysis results show the average value of wind speed in the Tower Turyapada area in February - March amounted to 3.55 m / s and 4.58 m / s. The wind turbine specification uses TSD-500. Wind turbine specifications use TSD-500 because it can generate electricity at low wind speeds and uses 10 units of turbines. The results of the analysis obtained electrical energy of 2,159 kWh / year. The electrical load requirement of the Pedestal Building as the main building of the Turyapada Tower Technology Park is 7,787,000 kWh / year, so it cannot meet the electrical load of the Pedestal Building because it only supplies power by 0.00028%. This research was conducted to find out how much wind energy can produce electrical energy with wind energy conditions in the Turyapada Tower Area.

Design, Fabrication, and Testing of Small Wind Pump

The demand for energy used to pump water for irrigation has been increasing, resulting in the need for alternative renewable energy sources to reduce costs. A study was conducted to develop a small wind pump that could be used to irrigate crops. The wind pump's efficiency, discharge, and actual power generated were evaluated, and regression analysis and the coefficient of determination were used to determine the goodness of fit. Results showed that the wind pump required a minimum wind speed of 0.3 m/s produced a discharge of 0.95 L/min, while a 4.13m/s wind speed produced a water discharge of 5.45 L/min. The efficiency of the wind pump was measured using the regression equation E= - 04075(ws)² - 0.6375(ws) + 14.36, where R² = 0.6201, resulting in a maximum efficiency of 20.56% and a minimum of 5.57%. This indicates that the wind pump was efficient at low wind speeds due to the dynamic stress of the pump lift rod and a mismatch between the rotor and pump characteristics. Lastly, the net benefit of Php 25,083.61 per year was derived, with a return on investment of 33.86%, which will be paid back in 1.26 months.

Comprehensive study of vortices interaction and blades height effect in a Darrieus vertical axis wind turbine with J‐type blades

AbstractThere is a growing demand to improve the performance of vertical axis wind turbines to facilitate their commercialization for application in urban areas. This study utilizes a 3D numerical analysis to examine the influence of different vortices generated on turbine efficiency with straight and J‐type blades. The numerical simulation of this study employs the Reynolds‐Averaged Navier–Stokes equations and ‎sliding ‎mesh techniques ‎to more accurately model the rotational motion of blades about the turbine axis in relation to the ‎wind. Comparing the output ‎torque and the flow field at different span‐wise sections, the J‐type blades achieve better ‎performance at mid‐spans where the effect of stall vortices is dominant. Conversely, the lower ‎performance of J‐type blades is seen at tip spans due to stronger tip vortices. Investigations also ‎reveal the criticality of the downwind region on the overall performance at high tip speed ratios. It is observed that by ‎increasing the height, the tip vortices are limited to the tip sections, and stall vortices expand further ‎along the blade. At TSR = 1, the improvement by J‐type blades rises from 10% at a height of 0.8 m to 44% ‎at 3 m. The growth in height at lower wind speeds becomes more beneficial. Compared to the straight blades, the self‐starting ‎generated torque by J‐type blades for heights of 0.8, 1.2, and 1.6 m, are improved by 15.6%, ‎‎26.9%, and 34.7%, respectively. Overall, it is concluded that by increasing the blade height, the superiority ‎of the J‐type blade becomes more noticeable as the blade mainly contributes to suppressing the stall ‎vortices effect where the tip vortices effect is not presented. ‎

A Statistical Analysis of Commercial Articulated Industrial Robots and Cobots

This paper aims to elucidate the state-of-the-art, prevailing priorities, and the focus of the industry, and identify both limitations and potential gaps regarding industrial robots and collaborative robots (cobots). Additionally, it outlines the advantages and disadvantages of cobots compared to traditional industrial robots. Furthermore, three novel factors are introduced in this survey as metrics to evaluate the efficiency and performance of industrial robots and cobots. To achieve these purposes, a statistical analysis and review of commercial articulated industrial robots and cobots are conducted based on their documented specifications, such as maximum payload, weight, reach, repeatability, average maximum angular speed, and degrees of freedom (DOF). Additionally, the statistical distributions of the efficiency factors are investigated to develop a systematic method for robot selection. Finally, specifications exhibiting strong correlations are compared in pairs using regressions to find out trends and relations between them, within each company and across them all. The investigation of the distribution of specifications demonstrates that the focus of the industry and robot makers is mostly on articulated industrial robots and cobots with higher reach, lower payload capacity, lower weight, better repeatability, lower angular speed, and six degrees of freedom. The regressions reveal that the weight of robots increases exponentially as the reach increases, primarily due to the added weight and torque resulting from the extended reach. They also indicate that the angular speed of robots linearly decreases with increasing reach, as robot manufacturers intentionally reduce the angular speed through reductive gearboxes to compensate for the additional torque required as the reach extends. The trends obtained from the regressions explain the reasons behind these interrelationships, the design purpose of robot makers, and the limitations of industrial robots and cobots. Additionally, they help industries predict the dependent specifications of articulated robots based on the specifications they require. Moreover, an accompanying program has been developed and uploaded on to GitHub, taking the required specifications and returning a list of proper and efficient robots sourced from different companies according to the aforementioned selection method.

An Analysis of Air Conditioning System Operation Patterns on Droplet Particle Distribution in a Classroom-A CFD Approach

In the classroom context, the transmission of pathogens among students is a significant concern. Therefore, it is important to determine appropriate airflow patterns, the placement of supply and exhaust ventilation, and the optimization of classroom design to reduce the risk of pathogen transmission. This research aims to determine the performance of two air conditioning (AC) operating patterns—low speed and high speed—in six scenarios involving window and door configurations and identify the most effective strategies for minimizing virus exposure to occupants in classrooms. The method used in this research is numerical simulation with the 3D unsteady k-ε RNG model to simulate air flow and the Eulerian-Lagrange approach to capture the movement of SARS-CoV-2 aerosol droplets. The results of this research show that of the six scenarios determined by the researchers, the low-speed AC operating pattern with an incoming air speed of 3.5 m/s occurs in scenario 5, that is, all windows open and doors closed. This is based on the lowest number of students exposed to the virus, which is 22.22%. Meanwhile, the high-speed AC operating pattern with an incoming air speed of 6 m/s occurs in scenario 2, that is, all windows closed and doors open. This is based on the lowest number of students exposed to the virus, which is 22.22%, so it can be concluded that increasing the air flow speed originating from the AC will speed up the droplets to leave the room through the outlet. Meanwhile, increasing the outlet capacity will shorten the particle path, thereby shortening the time when the droplets are in the classroom.

Frictional Wear Behavior of Water-Lubrication Resin Matrix Composites under Low Speed and Heavy Load Conditions.

Resin matrix composites are commonly utilized in water-lubricated stern tube bearings for warship propulsion systems. Low-speed and high-load conditions are significant factors influencing the tribological properties of stern tube bearings. The wear characteristics of resin-based laminated composites (RLCs), resin-based winding composites (RWCs), and resin-based homogeneous polymer (RHP) blocks were investigated under simulated environmental conditions using a ring-on-block wear tester. Simulated seawater was prepared by combining sodium chloride with distilled water. The wetting angle, coefficient of friction (COF), and mass loss were measured and compared. Additionally, their surface morphologies were examined. The results indicate a significant increase in the COFs for the three materials with an increased speed or load under dry conditions. The COF of the RLCs is the lowest, indicating that it has superior self-lubricating properties. In wet conditions, the COFs of the three materials decrease with an increasing speed or load, exhibiting a pronounced hydrodynamic effect. The COF and mass loss of RWCs are the highest, while RLCs and RHP exhibit lower COFs and mass loss values. The reticulated texture and flocculent fibers on the surface of RLC enhance the heat diffusion and improve the material wettability and water storage capacity. The surface of RWC is dense, and the friction area under dry conditions is melted and brightened. The surface of RHP is smooth, while the worn material forms an agglomerate and exhibits susceptibility to burning and blackening under dry conditions. The laminated formation method demonstrates superior tribological performance throughout the wear evolution process.

Morphodynamics of melting ice over turbulent warm water streams

We investigate the morphodynamics of an ice layer over a turbulent stream of warm water using numerical simulations. At low water speeds, characteristic streamwise undulations appear, which can be explained by the Reynolds analogy between heat and momentum transfer. As the water speed increases, these undulations combine with spanwise ripples of a much greater length scale. These ripples are generated by a melting mechanism controlled by the instability originating from the ice–water interactions, and, through a melting/freezing process, they evolve downstream with a migration velocity much slower than the turbulence characteristic velocity.

Reversing accidents involving pedestrians: an epidemiological investigation and cluster analysis using a novel database derived from Swedish National Register data

Objectives In contemporary urban environments, the intersection between Vulnerable Road Users, specifically unprotected pedestrians, and motor vehicles poses a persistent challenge to road safety. Reversing accidents, characterized by vehicles moving backward, often result in severe consequences for pedestrians due to limited visibility and inherent blind spots for the driver. This paper aims to provide a thorough examination of reversing accidents involving pedestrians in Sweden between 2000–2021; shedding light on the magnitude of the problem, contributing factors, consequences, and potential mitigation strategies. Method Using a national database, reversing accidents were compiled by classifying free text descriptions of traffic accidents reported to the Swedish Traffic Accident Data Acquisition. The database was then used to describe reversing accidents and their consequences for struck pedestrians using descriptive epidemiology and cluster analysis. Results The results show that reversing accidents accounted for 12% of all pedestrians injured in a collision with a motor vehicle in Sweden during the studied period. In terms of personal characteristics, the struck pedestrians were more often female and of old or young age, whilst the drivers of the reversing vehicles were more often between 18–54 years and men. Most accidents were non-fatal, with only roughly 2% resulting in fatalities. Through a cluster analysis, four distinct accident types were identified. Two of these were identified as particularly important to prioritize in future preventative work: accidents that are characterized by occur during daylight hours in the urban environment (often low speeds) and often result in fatality or serious injury. Conclusions Due to the low speeds, reversing accidents are rarely fatal. However, they account for a large proportion of accidents with pedestrians and can be grouped into clearly distinguishable accident types that can function as templates in road safety development in Sweden.

Enhancing work zone crash severity analysis: The role of synthetic minority oversampling technique in balancing minority categories

Road work zones are becoming increasingly common due to the aging infrastructure and the need for capacity enhancement. They present significant safety risks due to narrow lanes, uneven traffic flow, lower speed, and reduced visibility. It is particularly important to understand the role of human behavioral factors in WZ crash injury severity due to difficulty navigating such areas. Furthermore, the crash injury data available is mostly imbalanced, primarily due to the lower incidence of high-cost fatal and severe injuries, and can benefit from the use of emerging analysis techniques. This research study examines a unique dataset comprising 7,855 WZ crashes in Tennessee from 2018 to 2022 as a case study to provide useful insight into the behavioral factors associated with injury severity and how they change after adjusting for the underrepresented fatal and serious injuries within the dataset. The study applies frequentist methods and a machine learning technique enhanced with the Synthetic Minority Oversampling Technique (SMOTE), addressing the data imbalance (relatively fewer fatal and serious injuries) for useful inferences and predictions. The study results indicate that aggressive driving, overspeeding, and drunk driving significantly elevate injury severity. Additionally, after balancing the minority categories of crash injury severity levels, the importance of contributing factors changes. The study offers engineers and data analysts a framework for analyzing imbalanced data, a prevalent issue in crash injury severity analysis. By exploring key behavioral factors responsible for injury severity in WZ crashes, the study provides useful insight and valuable information to traffic safety engineers, transportation agencies, and policymakers to implement enhanced safety measures in WZ design and management, ultimately aiming to mitigate injury severity and to improve overall safety for road users.

Strategic selection of wind turbines for low wind speed regions: Impact on cost and environmental benefits

ABSTRACT Integrating renewable energy sources into the power system is essential for rapid and cost-effective decarbonization. This study evaluates the potential of a wind farm by analyzing three turbine models – VESTAS, GAMESA, and W2E – with power capacities from 2.5 MW to 8 MW. The analysis focuses on Region III, characterized by wind speeds below 7.5 m/s. Using the RETScreen model, the study identifies an optimized wind-rated power (OWRP) that balances financial viability, technical performance, and capacity factors. Monte Carlo simulations and sensitivity analyses assess financial indicators such as the levelized cost of energy, net present value, and equity payback period. The framework also considers greenhouse gas (GHG) credits. Results show that turbines with 4.5 MW power, rotor diameters of 105–128 m, and hub heights of 150 m are the most feasible. The project would reduce annual CO2 emissions by 187,097 tons and avoid 82,031 tons of fossil fuel consumption, equivalent to 17,559 hectares of forest CO2 absorption or 190,915 people cutting energy use by 20%. Without GHG credits, the equity payback period is 6.2 years; with a €50/tCO2 credit, it drops to 2.7 years. These findings offer policymakers in Albania and similar low-wind regions a guide to meeting 2050 energy and climate targets.

Links between atmospheric aerosols and sea state in the Arctic Ocean

Sea spray emission is the largest mass flux of aerosols to the atmosphere with important impact on atmospheric radiative transfer. However, large uncertainties still exit in constraining this mass flux and its climate forcing, in particular in the Arctic, where sea ice and relatively low wind speed in summer constitute a significantly different regime compared to the global ocean. Sea state conditions and marine boundary layer stability are also critical variables, but their contribution is often overlooked. Here we present concurrent observations of sea state using a novel stereo camera system, of sea spray through coarse mode aerosols, and of meteorological variables to determine boundary layer stability in the Barents and Kara Seas during the 2021 Arctic Century Expedition. Our findings reveal that aerosol concentrations were highest over open waters, closely correlating with wave height, followed by wind speed, wave steepness, and wave age. Notably, these correlations were stronger under unstable marine boundary layer conditions, reflecting immediate sea spray generation. By analysing various combinations of sea and atmospheric variables, we identified the wave height Reynolds number as the most effective indicator of atmospheric sea spray concentration, explaining 57% of its variability in unstable conditions. Our study underscores the need to consider sea state, wind, and boundary layer conditions together to accurately estimate atmospheric sea spray concentrations in the Arctic.

Effect of ignition timing on combustion characteristics and emissions of an X-type rotary engine with the high efficiency hybrid cycle

X-type rotary engines (XREs), using the high efficiency hybrid cycle, possess advantages of simple structure, high power-to-weight ratio, and high theoretical efficiency, making XREs as potential power sources in hybrid vehicles and small unmanned aerial vehicles. Typically, ignition timing has a promising potential to improve the combustion performance of spark ignition engines. In this work, the effects of ignition timing on flame propagation, combustion characteristics, and pollutants formation were studied adopting a three-dimensional simulation method. The results showed that at different engine speeds, significantly different flow forms and flow velocities in the larger chamber recess of the XRE were formed, resulting in large differences in flame propagation velocities at leading side and trailing side of the combustion chamber. Advancing ignition timing increased the flame propagation velocity at the given engine speed. Ignition timing had a more significant effect on peak pressure at medium-high speeds compared to low engine speeds. At 3000 RPM and 5000 RPM, the peak pressure was increased significantly with advancing ignition timing, but when ignition timing was advanced to -30 °CA, the increment in the in-housing pressure was minimal. As ignition timing was retarded, the ignition delay was slowly reduced. The effect of ignition timing on ignition delay was more significant for low speeds than for medium-high speeds. However, the influence of ignition timing on combustion duration showed the opposite trend. Delayed ignition showed a slight increase in indicated thermal efficiency and indicated mean effective pressure at low speeds, while the opposite was true at medium-high speeds. Nevertheless, the effect of ignition timing and engine speed on indicated specific fuel consumption is opposite to the trend of the above laws. With the increase of ignition timing, the NOx mass fraction first increased and then decreased at low speeds, with the maximum occurred at -30 °CA, but the NOx mass fraction continued to increase at high speeds. Soot and CO productions were slightly affected by ignition timing. To sum up, this XRE, setting the ignition timing of -30 °CA, achieved better flame propagation and engine performance at the price of a smaller increment of NOx emissions.

Evaluation of magnetic orientation in dual-stator linear permanent magnet vernier machine for wave energy conversion

The Permanent Magnet Vernier Machine (PMVM) is favored for wave energy conversion due to its high torque production at low speeds and straightforward design. This study introduces the innovative Dual Stator Linear Permanent Magnet Vernier Machine (DSLPMVM) with concentrated winding. In this design, permanent magnets (PMs) are strategically placed on both the stator and a segmented translator, enhancing system reliability. The stator utilizes a simple PM layout, while the translator features a Halbach array. This research advances the DSLPMVM’s performance through the optimal placement and orientation of magnets, alongside a meticulous selection of tooth types. The paper rigorously evaluated all possible magnetic orientations and eight distinct stator tooth models. Detailed comparisons of flux linkage, back electromotive force (back-EMF), inductance, efficiency, power factor (PF), and force were conducted to identify the most effective designs.

Toward green container liner shipping: joint optimization of heterogeneous fleet deployment, speed optimization, and fuel bunkering

AbstractContainer liner shipping companies, under the international shipping carbon reduction indicators proposed by the International Maritime Organization, must transform two key aspects: technology and operations. This paper defines a green liner shipping problem (GLSP) that integrates the deployment of a heterogeneous fleet, speed determination, and fuel bunkering. The objective is to achieve low‐carbon operations in liner shipping, taking into consideration the diversification of power systems, the use of alternative fuels in ships, and the continuous improvement of alternative fuel bunkering systems. For this purpose, we present a bi‐objective mixed integer nonlinear programming model and develop two methodologies: an epsilon‐constraint approach and a heuristic‐based multi‐objective genetic algorithm. We validate the effectiveness of our model and methods through a case study involving container ships of various sizes deployed on intra‐Asian short sea routes by SITC International Holdings Co., Ltd. The experimental results highlight the crucial role of dual‐fuel (DF) ships in the pursuit of low‐carbon strategies by liner companies, with liquefied natural gas and ammonia DF ships being the most widely used. Additionally, fuel cell (FC) ships, particularly those powered by ammonia and hydrogen, demonstrate significant carbon reduction potential. Furthermore, ships with larger container capacities have a greater cost advantage. For the GLSP, speed determination is an auxiliary decision, and the lowest speed is not necessarily the optimal choice. Decision‐makers must carefully balance competing economic and carbon emission reduction objectives, as deploying more alternative fuel ships may increase fuel bunkering and fuel consumption, resulting in a higher total operating cost.

Design of a six-phase surface mounted permanent magnet synchronous motor with application to electric trucks

As we have known, permanent magnet synchronous motors (PMSMs) have garnered widespread interest across various industrial applications thanks to their advantages such as high efficiency, reliable performance, simple structure, and adaptability to various shapes and sizes. Due to characteristics of the high torque and low speed, the PMSMs make particularly well-suited for traction applications such as trucks, ship propulsion, mining, and more. In this context, a combination of the analytical method and finite element method (FEM) is proposed for designing and simulating a six-phase surface-mounted PMSM. Firstly, a model of the six-phase PMSM is analytically design to make required/main dimensions. The FEM is then applied to analyse and verify electromagnetic parameters such as of the current waveform, back electromagnetic force (EMF), magnetic flux density in the air gap, flux linkage, torque, cogging torque, torque ripple and harmonic components. Via the obtained results, the research will give a contribution of valuable insights for optimizing the design, performance and reliability for this motor in diverse industrial applications.

The Effectiveness of Moringa Oleifera Seed Powder and Mixing Time (Fast-Low Speed) Using Jartest in Reducing Nitrate Levels in River Water

Background:Moringa oleiferais a fast-growing, long-lived plant that blooms throughout the year and can withstand extreme arid conditions. Objective:This study aims to examine the effectiveness of Moringa oleiferaseed powder in reducing nitrate levels in river water. Method:The research method employed in this study involved analysis using the Paired Sample Statistical Test. Result:The statistical test results revealed a significance value of 0.017 (p &lt; 0.05) and a mixing time variation significance of 0.011 (p &lt; 0.05). These values indicate that the null hypothesis (H0: there is no relationship between the independent and dependent variables) is rejected, while the alternative hypothesis (Ha: there is a relationship between the independent and dependent variables) is accepted. This implies a significant difference in the reduction of nitrate levels between the pretest and posttest data, demonstrating that the use of Moringaseed powder is effective in reducing nitrate levels. Conclusion:This study concludes that the administration of Moringaseed powder at a dose of 400 mg/L, with a mixing time of 2 minutes at a fast speed (80 rpm) and 20 minutes at a low speed (40 rpm), is most effective in significantly reducing nitrate levels in river water. Keywords:Moringa oleifera; nitrate levels; river water; Indonesia