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Ducted wind turbines are a kind of small wind turbine having a diffuser or any other shape around the rotor which increases the air flow through the blades and absorbs more power. In the present study, a small wind turbine was ducted with a relatively simple ring and its performance was investigated in a wind tunnel. The duct is shaped using rolling steel sheets on a sloping surface and finally fabricated in double-glazed surfaces. The turbine utilizes polyester resin glass fiber-armed composite hollow blades. Bare turbine produces 165 watts in its highest power generation mode which can reach 282 watts when it is ducted. The evaluation of the system in the wind tunnel showed that the power generation of the ducted system compared to a conventional turbine was 14 % higher on average. Furthermore, the rotor speed of the ducted turbine was 45 % higher than the bare one which increases the tip speed ratio (TSR). In this study, TSR increment raised the absorbed power in the developed wind turbine.

The radial reduction of a billet in a radial-forging machine (RFM) with the jigging motion of levers with heads is considered. The maximum metal feed in forging is determined to effectively choose the machine drive elements. To this end, we derive expressions to describe the motion of working tool during radial forging in RFM and equations for the drive power balance and the nonuniformity of machine running. In addition, the condition for the acceleration of the drive flyweight during the idle time of RFM is determined. Parametric analysis is performed to determine the maximum billet feed into heads for a number of electric engines and various reduced flywheel weights used in RFM with the jigging motion of heads. [ABSTRACT FROM AUTHOR]

• A new strategy is proposed for vibration control of flexible pendulums. • We introduce a flywheel to control flexible pendulum vibration. • The control method has robustness and is effective for nonlinear forced vibration. • An experiment platform is built to validate the proposed control strategy. Flexible inverted pendulums have found wide applications in mechanical systems, but their stability is susceptible to external disturbances. In this study, a new strategy that employs a flywheel to suppress vibration of flexible inverted pendulums is proposed. We develop the theoretical dynamic model of flexible pendulums with a flywheel by the Euler-Bernoulli beam theory, where the axial displacement of the pendulum and geometric nonlinearities are considered. An active control method based on the Bézier trajectory is proposed, where the acceleration of the flywheel is set as the input. Additionally, the equivalent damping ratio of the system including flywheel's motion is derived. The relationship between the parameters in the control equation and the suppression effect is obtained through the simulation of the equivalent damping ratio. Then, an experimental platform is built. The experimental results show that the present control strategy has good suppression effect on the vibration of the flexible inverted pendulums when selecting appropriate parameters. Meanwhile, the results of anti-disturbance test show that the present method has a certain robustness. Finally, the simulation results show that this strategy is also effective for nonlinear forced vibration under different excitation frequencies. [ABSTRACT FROM AUTHOR]

A hydraulic excavator (HE) is a typical piece of construction equipment and is widely used in various construction fields. However, the poor energy efficiency of HEs results in serious energy waste and has aroused the attention of researchers. Furthermore, rising fuel prices and increasing stringent waste gas emission legislation sparked demand for ways to improve energy efficiency. Recovering the otherwise wasted boom potential energy of a conventional HE by proper methods offers the potential to improve the fuel efficiency of HEs. In this paper, a mechanical energy recovery system consisting of a pump/motor and a flywheel is presented for HEs using a load sensing system. When the boom moves down, the boom potential energy is converted into mechanical energy by the boom cylinder and the pump/motor to accelerate the flywheel. When needed, the captured energy stored in the flywheel is converted back into a form of pressure energy to directly drive the boom cylinder up without throttling the main valve. In the lifting process, a compound circuit that consists of a throttling control circuit and a displacement control circuit is presented. A control strategy is proposed to optimize the energy recovery and reuse procedure. A 4-t HE is used as a study case to investigate the energy-saving potential of the proposed system. Numeric simulations show that the proposed system, when compared with a conventional load sensing system, can reduce as much as 48.9% energy consumption in a non-loaded cycle of boom lifting and lowering process. As to a fully loaded case, the energy-saving rate is 16.9%. This research indicates the flywheel-based scheme is promising for developing an energy-efficient fluid power system for HEs and reducing energy consumptions.

In this paper, the technical data provided by the sellers of an exercise bike FALCON SG-911B SAPPHIRE have been verified. After dismantling the bike, the dimensions of the components of the transmission of motion were measured and the mass parameters of the flywheel were set. In order to increase the mass moment of inertia reduced to an axis of the crankshaft, construction changes were proposed. The values of the braking torque of the magnetic brake at subsequent resistance levels were measured. The cycling test was performed and the distance, calories burned and heart rate read from the counter were verified computationally.

The primary aim of this study was to investigate the intra- and inter-day reliability of flywheel cluster set training in concentric power (CON), eccentric power (ECC), and ECC overload during the Romanian deadlift exercise (RDL). A secondary aim was to assess the acute effect of internal and external attentional focus instructions on mean power when performing the flywheel RDL. Fourteen collegiate male field sport athletes (age, 23.3 ± 3.7 years; mass, 80.8 ± 9.9 kg; height, 1.79 ± 0.06 m) were randomized into internal ( n = 7) or external ( n = 7) attentional focus groups and attended four testing sessions, with a between-session separation of 7 days. Sessions consisted of four cluster sets of fifteen repetitions "excluding momentum repetitions" (4 × (5 + 5 + 5)) using a specific inertial load (0.025, 0.050, 0.075, and 0.100 kg·m -2 ) for a given set in a randomized ascending or descending order. Cluster sets were separated by a 45 s intra-set rest period. Both instructional focus groups attained familiarization, although the time taken to achieve familiarization (outcome stability) differed between groups. The external instructional group attained familiarization post-session 2 (Cohen's d (ES), ES = 0.11-0.65) with little volatility between performance measures (CV% = 4.61-9.59). Additionally, the internal group reported inconsistencies among all inertial loads, reporting large differences in MP in the 0.100 kg·m -2 inertial load from day 2 to day 3 (ES = 1.22) and both 0.050 kg·m 2 ( p = 0.010) and 0.075 kg·m -2 ( p = 0.016) between day 3 and day 4. The flywheel RDL cluster set approach is a reliable training modality for maintaining mean power output during cluster set repetitions.

In this paper, the integration of the dynamic behavior of the flywheel system into the load simulation tool OpenFAST is presented. The flywheel system enables a wind turbine to vary the inertia of its rotor blades to control the power production and, most importantly, to affect the vibratory behavior of wind turbine components. Consequently, in order to simulate the behavior of a wind turbine with a flywheel system in its rotor, the variable blade characteristics need to be considered in the load simulation tool. Currently, computer-aided engineering tools for simulating the mechanical loads of wind turbines are not designed to simulate variable blade inertia. Hence, the goal of this paper is to explain how variable inertias of rotor blades are implanted in such load simulation tools as OpenFAST. OpenFAST is used because of it is free, publicly available, and well documentation. Moreover, OpenFAST is open source, which allows modifications in its source code. This add-on in the load simulation is applied to correct rotor mass imbalance. It can also be applied in many cases related to the change in the inertia of wind turbine rotor blades during its operation as, for example, atmospheric ice accretion on the blades, smart blades, etc.

Wind power penetration increases in most grids and the sizes of wind turbines increase. This leads to increasingly tough requirements, which are imposed on wind turbines, both from the grid as well as from economics. Some of these partially contradictory requirements can only be satisfied with additional control mechanisms in the wind turbines. In this paper, such a mechanism, i.e., a hydraulic–pneumatic flywheel system in the rotor of a wind turbine, is discussed. This flywheel system supports a wind turbine in providing grid services such as steadying the power infeed, fast frequency response, continuous inertia provision, power system stabilization, and low voltage ride-through. In addition, it can help mitigate the stress on the mechanical structure of a wind turbine, which results from varying operating points, imbalances in the rotor, gravitation that acts on the blades, in-plane vibrations, and emergency braking. The study presented in this paper is based on simulations of a publicly available reference wind turbine. Both the rotor blade design as well as the design of the flywheel system are as previously published. It is discussed how the aforementioned grid services and the stress reduction mechanisms can be combined. Finally, it is concluded that such a flywheel system broadens the range of control mechanisms of a wind turbine substantially, which is beneficial for the grid as well as for the wind turbine itself.

Flywheel energy storage system (FESS) is new advanced machinery which is intended for electric power storage and release. A FESS, which is suitable for the small flywheel, was developed with a permanent magnet bearing (PMB) and a single point flexible support, and its friction loss is very low. By means of the Lagrange theory, a dynamic model was established. The Campbell diagram, mode shapes, modal damping ratios and critical speeds were designed after the flywheel data at different operating speeds was obtained by numerical simulation. Based on the excitation test and single freedom vibration theory, the stiffness and damping coefficient of the upper and lower damper was measured. The influences of damper dynamic parameters on modes of flywheel rotor bearing system were discussed in detail. The comparison between the calculated unbalance response and the experimental response indicates that the dynamic model is appropriate. The results showed that the lower damper absorbed vibration energy of the flywheel rotor, which increased vibration of the damping body. And the bigger damping coefficient had better vibration absorption effect. The developed FESS is simple, stable and efficient in structure. [ABSTRACT FROM AUTHOR]

Summary: The demand of electric energy is increasing globally, and the fact remains that the major share of this energy is still being produced from the traditional generation technologies. However, the recent trends, for obvious reasons of environmental concerns, are indicating a paradigm shift towards distributed generation (DG) incorporating renewable energy resources (RERs). But there are associated challenges with high penetration of RERs as these resources are unpredictable and stochastic in nature, and as a result, it becomes difficult to provide immediate response to demand variations. This is where energy storage systems (ESSs) come to the rescue, and they not only can compensate the stochastic nature and sudden deficiencies of RERs but can also enhance the grid stability, reliability, and efficiency by providing services in power quality, bridging power, and energy management. This paper provides an extensive review of different ESSs, which have been in use and also the ones that are currently in developing stage, describing their working principles and giving a comparative analysis of important features and technical as well as economic characteristics. The wide range of storage technologies, with each ESS being different in terms of the scale of power, response time, energy/power density, discharge duration, and cost coupled with the complex characteristics matrices, makes it difficult to select a particular ESS for a specific application. The comparative analysis presented in this paper helps in this regard and provides a clear picture of the suitability of ESSs for different power system applications, categorized appropriately. The paper also brings out the associated challenges and suggests the future research directions. [ABSTRACT FROM AUTHOR]

This paper investigates the development and application of a nonlinear adaptive intelligent controller with superior disturbance-rejection capability for a doubly-fed-induction-machine driven flywheel energy storage system (FESS), to mitigate the intermittency in wind power injection, as well as enhance the transient stability of the connected multimachine power system thereby isolating the grid power from fluctuations. Intelligent supervisors for the rotor-side-converter of the FESS have been constructed using a fuzzy rule set. The consequent part in every rule includes a wavelet function for function learning. The novel normalized gradient descent algorithm with adaptive learning rate has been used to derive the update laws for unknown controller parameters. The control law has been derived by minimizing the predictive performance index. Convergence of the developed algorithm is guaranteed as proven via the Lyapunov stability method. Realistic wind speed profile has been used to test the efficacy of the developed control scheme. The sizing strategy has been devised for optimal sizing of FESS for its efficient utilization. Modified WSCC nine-bus test system has been used for the nonlinear time-domain simulations and novel indices have been used for evaluation of controller performance against its predecessors. $\boldsymbol{OP}{\text{5600}}$ Real-Time-Digital-Simulator has been used to demonstrate the real-time implementation of the suggested scheme. [ABSTRACT FROM AUTHOR]

This paper investigates the physical capability of double‐fed induction generator (DFIG) wind turbines for inertial support of frequency response. Frequency stability is modeled using the DFIG electromechanical and generator controller dynamics, and a destabilizing effect is demonstrated in low‐inertia systems. To improve response, a synchronous reference frame DFIG controller is proposed that acts by following low‐frequency grid dynamics and adds a fast acting proportional plus integral (PI)‐controlled frequency‐responsive component to existing qd current commands. The proposed controller is derived in a straightforward manner using only the DFIG dynamic equations and is designed using pole/zero placement techniques. Laboratory experiments using a micro‐scale DFIG wind turbine with hub‐emulating flywheel prove better capability for transient frequency regulation even under extreme load change. The result is a DFIG controller that balances the appearance of transients in electrical and mechanical systems. Value is achieved in providing immediate continuous inertial response to support load change. The proposed frequency response can improve the use of existing physical inertia from wind turbines. [ABSTRACT FROM AUTHOR]

The Jovian flywheel model was developed to explain the remarkable steadiness of the observed corotation lag in Jupiter's magnetosphere. The key conclusion of that research was that the observed lag is primarily due to slippage within the neutral atmosphere, with only a small fraction of it arising from slippage between the thermosphere and magnetosphere. Moreover, the neutral wind profile in the atmosphere responds very slowly, so it acts as a mechanical flywheel to dampen out temporal variations with timescales less than several months. We adapt the model for Saturn by allowing the Pedersen conductance to differ in the northern and southern hemispheres. In steady state, the two neutral thermospheres then have different rotation rates that can slowly vary with the season on Saturn as solar illumination of the poles varies. Plain Language Summary: The time for Saturn to rotate once is difficult to measure from Earth. For many questions, the key is the magnetic field's rotation period, which is fixed to the planet's core. Voyager measured regular variations in the magnetic field and radio waves that implied a rotation period of 10 hr, 40 min, which was accepted as Saturn's period for over two decades. When Cassini arrived, the rotation period was 10 min longer and slowly varied over the next 13 years. Additional data showed that the north and south hemispheres actually have different varying slowly periods. We propose an explanation. As charged particles move through Saturn's magnetic field (its "magnetosphere"), they change rotational speed, just as ballet dancers change speed by shifting their limbs. This puts electromagnetic stress on the planet's atmosphere and causes a high‐altitude layer to rotate more slowly. The summer hemisphere is more directly exposed to solar ultraviolet radiation, which makes it conduct electricity better. Electrical currents go preferentially to that hemisphere, which slows the atmosphere more than in the winter hemisphere. The result is a longer summer period compared to the winter. As the seasons change, the rotation periods should swap between North and South, as is observed. Key Points: Seasonal ionospheric conductivity variations cause magnetospheric plasma dynamics to exert unequal torques on Saturn's neutral atmosphereThe northern and southern thermospheres acquire unequal rotation periods that vary slowly because of their very large moments of inertiaEffects of ionosphere‐thermosphere coupling can show simultaneous, unequal periods, thus explaining the observed variable dual periodicity [ABSTRACT FROM AUTHOR]

In this paper, the impact on the mechanical loads of a wind turbine due to a previously proposed hydraulic‐pneumatic flywheel system is analysed. Load simulations are performed for the National Renewable Energy Laboratory (NREL) 5‐MW wind turbine using fatigue, aerodynamics, structures, and turbulence (FAST). It is discussed why FAST is applied although it cannot simulate variable rotor inertia. Several flywheel configurations, which increase the rotor inertia of the 5‐MW wind turbine by 15%, are implemented in the 61.5‐m rotor blade. Load simulations are performed twice for each configuration: Firstly, the flywheel system is discharged, and secondly, the flywheel is charged. The change in ultimate and fatigue loads on the tower, the low speed shaft, and the rotor blades is juxtaposed for all flywheel configurations. As the blades are mainly affected by the flywheel system, the increase in ultimate and fatigue loads of the blade is evaluated. Simulation results show that the initial design of the flywheel system causes the lowest impact on the mechanical loads of the rotor blades although this configuration is the heaviest. [ABSTRACT FROM AUTHOR]

Seaports are specifically designed for trading purposes. They are equipped with facilities for handling industrial and commercial goods as well as raw materials stored in containers. These facilities are often based on diesel cranes, which are noisy and produce air pollution. A possible solution to address this problem is replacing the diesel-power cranes with the electric ones. This idea, however, demands a high power connection to the grid in the seaport. This paper presents a cost-effective and environmentally friendly solution based on an electrical flywheel system to reduce electricity consumption from the electrical power network while improving system efficiency by using already existing technologies. Besides, this study presents a new method for controlling electrical drives using flywheel energy storage systems in harbor crane applications by exploiting the energy harvested from the cranes. The system model, including the electrical grid, cranes, power electronic drives, and flywheels as energy storages, is presented and an effective control methodology is developed. Simulation results of a practical crane system are presented and discussed. Practical lab-scale setup is also built and tested. The results have shown that by using the proposed method, the energy can be effectively harvested from the crane into the flywheel energy storage system during its operation, which significantly enhances the harbor power system efficiency as well as supply quality. [ABSTRACT FROM AUTHOR]

In order to improve the energy recovery rate of the electric vehicle flywheel auxiliary energy storage system, the structure of the flywheel of the key component of energy storage is optimized. Under the condition of safety factor of 2, the improved differential evolution algorithm is used to optimize the design of the flywheel structure by Matlab combined with Ansys finite element analysis software. The flywheel structure with the highest energy storage density is obtained through algorithm optimization. Based on the algorithm-optimized flywheel, the spoke structure is designed to improve the radius of gyration. Finally, through the strength check, it can be concluded that the spokes structure can obviously improve the mass energy storage density, but the number of spokes has little effect on improving the mass energy storage density. The research shows that the improved differential evolution algorithm and the spoke structure jointly optimize the design of the flywheel, which can effectively improve the energy storage density of the flywheel, and provide a new idea for designing the structure of the flywheel. [ABSTRACT FROM AUTHOR]

The present study investigated the effects of in-season enhanced negative work-based training (ENT) vs weight training in the change of direction (COD), sprinting and jumping ability, muscle mass and strength in semi-professional soccer players. Forty male soccer players participated in the eight-week, 1 d/w intervention consisting of 48 squat repetitions for ENT using a flywheel device (inertia=0.11 kg•m-2) or weight training (80%1 RM) as a control group (CON). Agility T-test, 20+20 m shuttle, 10 m and 30 m sprint, squat jump (SJ) and countermovement jump (CMJ), lean mass, quadriceps and hamstrings strength and the hamstrings-to-quadriceps ratio were measured. Time on agility T-test and 20+20 m shuttle decreased in ENT (effect-size =-1.44, 95% CI -2.24/-0.68 and -0.75, -1.09/-0.42 respectively) but not in CON (-0.33, -0.87/0.19 and -0.13, -0.58/0.32). SJ and CMJ height increased in both ENT (0.71, 0.45/0.97 and 0.65, 0.38/0.93) and CON (0.41, 0.23/0.60 and 0.36, 0.12/0.70). Overall, quadriceps and hamstrings strength increased in both ENT and CON (0.38/0.79), but the hamstrings-to-quadriceps ratio increased in ENT (0.31, 0.22/0.40) but not in CON (0.03, -0.18/0.24). Lean mass increased in both ENT (0.41, 0.26/0.57) and CON (0.29, 0.14/0.44). The repeated negative actions performed in ENT may have led to improvements in braking ability, a key point in COD performance. Semiprofessional soccer players may benefit from in-season ENT to enhance COD and the negative-specific adaptations in muscle strength and hamstrings-to-quadriceps ratio. [ABSTRACT FROM AUTHOR]

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For years, engineers and designers have capitalized on electrochemical batteries for long-term energy storage, which can only last for a finite number of charge–discharge cycles. More recently, compressed hydrogen is being scrutinized as a large-scale storage medium but this poses the risk of spreading high-pressure vessels with inflammable content. Historically, flywheels have provided an effective way to smooth out speed fluctuations in irregular machines and mechanisms. With advancements in composite materials, magnetic bearings, and mechatronic drives, flywheels have become the subject of extensive research as power storage devices for mobile or fixed installations. Flywheel energy storage systems are considered to be an attractive alternative to electrochemical batteries due to higher stored energy density, higher life term, deterministic state of charge and ecological operation. The mechanical performance of a flywheel can be attributed to three factors: material strength, geometry, and rotational speed. Focusing on the simple relationship between these variables, this paper reviews the literature of flywheel technology and explores the merits of four simple but unconventional flywheel configurations that have not been examined so far. Two geometries assume the use of monolithic isotropic materials two solutions are based on the use of high-strength strips or tapes wound up to form a multilayered structure. [ABSTRACT FROM AUTHOR]

In this article, a methodology is presented for the design of a hydraulic-pneumatic flywheel integrated in a wind turbine rotor. The flywheel enables wind turbines to contribute to power system inertia and it can be used for mitigating loads on the wind turbine. The methodology is applied to the geometry of an existing blade design of a 5-MW wind turbine, but is valid for any arbitrary rotor blade. Several flywheel configurations are derived causing an increase in rotor inertia of the 5-MW wind turbine by 15%, but differ in the position, dimensions and masses of the hydraulic components. These parameters determine the total mass of the hydraulic-pneumatic flywheel, and hence the impact on the mechanical loads on the wind turbine. As a result, a weight-optimized configuration for a flywheel integrated in a wind turbine rotor is derived. [ABSTRACT FROM AUTHOR]

Bias and harmonic currents, which are caused by rotor gravity, mass imbalance and sensor runout, are the dominant disturbances of the hybrid magnetic bearing (HMB) systems. To reject these disturbances and realize the low power control, a novel internal model control method based on positive current feedback and repetitive control is proposed. The positive current feedback can tune the levitation position of the rotor adaptively so that the rotor gravity can be supported precisely by the force resulting from the permanent magnet in the HMB. To suppress the harmonic currents caused by the mass imbalance and sensor runout, a novel plug-in repetitive controller is proposed. Compared to the conventional repetitive controller, the low-pass filter is removed from the internal time lag loop outside so as to improve the system stability and reduce the elimination error of the high-order current harmonics. The absolute stability of the whole closed-loop system is analyzed by using the Nyquist criterion to the time-delay system with the help of the regeneration spectrum method. Upon the phase-frequency characteristic, phase compensators in low, middle, and high frequencies are designed, respectively. Both simulations and experiments are carried out to demonstrate the validity of the proposed control method. [ABSTRACT FROM AUTHOR]

In this research, we studied the rigidity of superconducting magnetic bearings (SMBs) due to the difference in superconductor arrangement. I The SMB with one large superconductor fabricated in a previous study and the SMB with two small superconductors arranged separately in this study were compared. The rigidity in the axial direction, radial direction, and pitching direction of each bearing were measured. However, since the total volume of the superconductor used for the two SMBs is different, the rigidity per unit volume was compared. The results confirmed that the rigidity per unit volume in all directions is larger when a plurality of small superconductors is used. In addition, this study verified the characteristics of each SMB by preparing a flywheel with two SMBs and rotating them. [ABSTRACT FROM AUTHOR]

Transmotor-based flywheel energy exchange is a low-cost yet highly efficient method of energy transfer between vehicle wheels and a lightweight flywheel. This method utilizes one dual-rotor electric machine that enables us to overcome some of the shortcomings of the conventional electric kinetic energy recovery systems (KERS).The proposed system is capable of capturing far more mechanical power than its electrical power ratings. Furthermore, since a significant part of the energy exchange takes place in mechanical form, only a small fraction of the initial kinetic energy needs to be processed by the electrical energy storage device and the power electronic drive system. In this paper, the proposed Transmotor-based KERS has been compared with the conventional electric KERS. Mathematical modeling and simulations were performed using a space vector modeling method for both conventional electric KERS and the proposed system. Results show that the proposed system is capable of capturing a great part of kinetic energy of a vehicle during deceleration and storing it in a lightweight flywheel to be used for the next acceleration while keeping the electrical ratings of the KERS relatively low. Experimental results are also presented for the proof of the concept. [ABSTRACT FROM AUTHOR]

This paper presents the development of a switched-reluctance machine (SRM) driven flywheel system, its charging/discharging controls, and performance evaluations. By properly setting and tuning the winding commutation instant, the same SRM can be operated as a motor and a generator in the SRM-driven flywheel system with satisfactory performances. Moreover, the hysteresis current controlled pulsewidth modulation scheme with hard freewheeling and the commutation angle dynamic shift controller are proposed to enhance the flywheel discharging generating performance. For interfacing the flywheel system to the dc microgrid, a half-bridge bidirectional dc–dc interface converter is developed. It is operated in a buck mode under flywheel charging and in a boost mode under flywheel discharging. The dynamic modeling and controller design are conducted to yield well-regulated dc output voltage under varying flywheel-driven switched-reluctance generator (SRG) speed. Finally, the measured results are given to verify the performances of the established flywheel and its interconnected operation to a wind SRG-based dc microgrid. [ABSTRACT FROM AUTHOR]

The cutting process of textile materials for costumes of hospitality facilities at the expense of use a new flywheel design is described in the article. A series of experiments was conducted, which allowed to explore the cutting process from point of view of equipment energy efficiency. Maximum values of energy consumption for layers from variety of materials for costume and coat fabrics were determined. Comparison of existing press equipment with improved allowed to establish the economic efficiency of its application. [ABSTRACT FROM AUTHOR]

This paper deals with the complete design procedure, implementation and control software realization for a multi-converter charging station with reduced grid impact due to local electromechanical energy storage. In particular, energy storage is accomplished by a dedicated flywheel designed and built for this purpose. The proposed charging station was designed for ultra-fast charging procedures presenting a strongly reduced impact on the electrical grid. Modes of operations are described with reference to pure electric buses in public transportation applications.

Electrification of transportation is an effective way to tackle climate change. Public transportation, such as electric buses, operate on predetermined routes and offer quiet operation, zero local emissions and high energy efficiency. However, the batteries of these buses are expensive and wear out in use. The battery ageing is expedited by fast charging and power spikes during operation. The contribution of this paper is the reduction of the power spikes and thus a prolonged battery lifetime. A novel hybrid energy storage system for electric buses is proposed by introducing a flywheel in addition to the existing battery. A simulation model of the hybrid energy storage system is presented, including a battery ageing model to measure the battery lifetime. The bus was simulated during its daily driving operation on different routes with different energy management strategies and flywheel configurations. These different flywheels as well as the driving cycle had a significant impact on the battery life increase. The proposed hybrid battery/flywheel storage system resulted in a battery lifetime increase of 20% on average.

With an increase in renewable energy generation in the United States, there is a growing need for more frequency regulation to ensure the stability of the electric grid. Fast ramping natural gas plants are often used for frequency regulation, but this creates emissions associated with the burning of fossil fuels. Energy storage systems (ESSs), such as batteries and flywheels, provide an alternative frequency regulation service. However, the efficiency losses of charging and discharging a storage system cause additional electrical generation requirements and associated emissions. There is not a good understanding of these indirect emissions from charging and discharging ESSs in the literature, with most sources stating that ESSs for frequency regulation have lower emissions, without quantification of these emissions. We created a model to estimate three types of emissions (CO2, NOX, and SO2) from ESSs providing frequency regulation, and compare them to emissions from a natural gas plant providing the same service. When the natural gas plant is credited for the generated electricity, storage systems have 33% to 68% lower CO2 emissions than the gas turbine, depending on the US eGRID subregion, but higher NOX and SO2 emissions. However, different plausible assumptions about the framing of the analysis can make ESSs a worse choice so the true difference depends on the nature of the substitution between storage and natural gas generation.

The purpose of this preliminary study was to describe changes in physical function and torque capacity in adults with chronic kidney disease (CKD) in response to a novel progressive eccentric-overload resistance exercise (ERE) regime. Participants included men (n = 4) diagnosed with CKD according to estimated glomerular filtration rate (eGFR) between 59 and 15 mL/kg/1.73 m2 and not requiring dialysis. Physical function was determined by the Short Physical Performance Battery (SPPB), five repetitions of a sit-to-stand (STS) task, and timed-up and go (TUG). Knee extensor strength was assessed using both isometric and isokinetic contractions and performance fatigability indexes were calculated during a 30-s maximal isometric test and a 30-contraction isokinetic test at 180°/second. None of the patients exhibited significant worsening in their health status after training. Participants demonstrated improvements in several measures of physical function and torque capacity following 24 sessions of ERE. Following training, performance fatigability remained relatively stable despite the increases in torque capacity, indicating the potential for greater fatigue resistance. These findings provide initial evidence for ERE as a potential treatment option to combat declines in physical function and neuromuscular impairments in people with CKD. Future research is required to determine optimal progression strategies for maximizing specific neuromuscular and functional outcomes when using ERE in this patient population.

Di zaman yang semakin modern ini banyak kebutuhan yang semakin meningkat, salah satunya adalah energi. Energi fosil yang digunakan pada mesin-mesin sebagai bahan bakar utama telah banyak digunakan. Pemanfaatan energi yang dilakukan secara berlebihan semakin menurunkan ketersediaan energi fosil tersebut. Untuk mengurangi ketergantungan pada energi fosil yang pembentukannya sangat lama dan cepat habis, maka dari itu dibutuhkan adanya pemanfaatan energi alternatifyang lebih ramah lingkungan dan mudah didapat.Penggunaan sepeda sebagai moda transportasi yang mudah dan bermanfaat menjadi salah satu pilihan. Memanfaatkan putaran roda untuk memutar alternerator yang nantinya akan menghasilkan listrik, kemudian energi listrik tersebut disimpan pada akumulator. Pada saat akan digunakan maka energi listrik pada akumulator disalurkan pada mesin saat berfungsi sebagai motor listrik untuk memutar roda belakang. Proses dalam menghasilkan energi listrik ini yang dimanfaatkan sebagai energi terbarukan pada penggunaan sepeda. Selain memanfaatkan putaran pada roda belakang yang disambungkan pada alternerator, bisa juga dengan memanfaatkan fly wheel yang disambungkan dengan transmisi rantai pada sepeda. Fly wheel tersebut dimanfaatkan putarannya pada saat sepeda berhenti atau melakukan pengereman. Beban berat pada fly wheel membuatnya bisa berputar terus dan membutukan waktu yang cukup lama untuk berhenti walaupun sumber tenaga pemutar telah berhenti. Hal ini yang dimanfaatkan dalamKinetic Energy Recovery System (KERS) pada mobil formula one dan diaplikasikan pada pengereman sepeda sebagai penghasil energi untuk memutar alternerator, agar pengisian akumulatortetap bisa dilakukan pada saat mengerem dan berhenti dari kecepatan tinggi. Dari hasil perhitungan, Dengan daya 1801 W pada kecepatan 25 km/jam energi kinetik flywheel sebesar 101,2 joule dan dapat menghasilkan arus listrik sebesar 0,78 amper pada putaran alternator 1661,83 rpm. Dengan menggunakan panjang rantai 1,49 meter pada roda belakang menuju flywheel dan 0,67 meter pada flywheel menuju alternator