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This paper presents a comprehensive review of the state-of-art high-speed dynamic comparators. The comparator is a critical block of high-speed, low-power analog-to-digital converters, determining the speed and overall power consumption. Therefore, the design of a high-speed comparator with tolerable offset, noise and power consumption is of utmost importance. Recent work reported on high-speed comparator topologies is investigated in detail with the help of simulations in 65 nm CMOS technology. Various parameters, such as delay, energy consumption, speed, offset, kickback noise, power delay product, etc., are compared. A detailed comparative study is also presented on several design methodologies. [ABSTRACT FROM AUTHOR]

The train operating speed is traditionally limited to lower than 0.7 times the critical speed of the catenary. The material's strength limits the tensile forces of the tension wires, preventing the further improvement of the train speed. A novel super-critical speed operating strategy of the pantograph catenary system (PCS) is proposed, using the relatively low tensile values of the catenary to make the pantograph run at a speed ratio larger than 1. The analytical results of a string under a moving load show the theoretical possibility of the super-critical speed operating strategy in moving load problems. The finite element method (FEM) is adopted for the model of the catenary. The differences between the simple catenary and the stitched catenary running at the super-critical speed regime are compared. Then, the tensile forces designation of the stitched catenary with different speed ratio values beyond 400 km/h is studied. Finally, the dynamic behaviours of the PCS reaching the super-critical speed regime are discussed, consisting of the continuous acceleration process and the transition process from the high-tension section to the low-tension section. The proposed super-critical speed operating strategy may be promising for the next-generation high-speed PCS. [ABSTRACT FROM AUTHOR]

• A chamber model considering pressure distributions of compressors is proposed. • An exhaustive mathematical model and an efficient solution method are provided. • More geometry features and compression mechanisms can be investigated. • Parametric studies are performed using the new model with good trends. Further efficiency improvements of screw compressors rely on computer modeling and mathematical analysis at the design stage. As speed and capacity increase, the uniformity assumption used in the conventional chamber model for twin-screw compressors is no longer suitable. At the same time, CFD simulations are complicated and time-consuming for design optimization. Therefore, in this paper, a chamber model considering pressure distribution is proposed, which is fast enough and more applicable. Each working unit of a screw compressor is considered a one-dimensional compressible transient flow with two moving pistons, which allow the passage of fluid. Numerical methods of the model are verified by a shock wave test. A twin-screw compressor was also simulated and the results of the chamber model were compared with the CFD results. Pressure fluctuations like those in previous experimental studies can be captured in the simulated indicator diagram. General trends with different speeds, suction ports, and wrap angles could also be recognized in the simulation results. The compression process and the influence of structural parameters on the compressor's functioning are revealed intuitively. By combining existing chamber models, the applicability of the new model can be further extended, and it is expected to be a helpful tool for compressor design. [ABSTRACT FROM AUTHOR]

Finite impulse response (FIR) filters are explicitly used in decisive applications such as communication and signal processing areas. Advancement in the latest technologies necessitates specific designs with optimal characteristics. This research work proposes the realization of an efficient distributed arithmetic adaptive FIR filter (DAAFA) architecture using radix-4 and radix-8 computation. Distributed arithmetic (DA) is extensively used to calculate the sum of products without involving a multiplier. The proposed fixed-point realization of a single multiply and accumulate (MAC) FIR adaptive filter is implemented with minimum complex design. The total longest-way computation time is a combination of the delay that occurred in the error calculation module and the delay involved in updating the filter weights. The longest-way computation time of the filter structure is higher, which results in increased latency. In addition, the approximate design of the radix DA multiplier structure is constructed using Booth recoding, partial product formation block and shifting-based accumulation block. Further, the approximate design of DA offers a reduction in complexity and area with respect to the number of slices and enhances the operating speed. The partial product is created using shifters and efficient adders, which further enhances the performance of the realization. This work is implemented in Xilinx and Altera devices and is compared with the present literature. From the synthesis results, it is observed that the propounded design outperforms in terms of complexity, slice delay product and ultimate speed of exertion. The suggested architecture was found to be decisive in terms of area, delay and complexity abatement. The results indicate that the propounded design achieves area reduction (slices) of about 92.03% compared to the existing design. Also, a speed enhancement of about 90.7% is accomplished for the proposed architecture. Nonetheless, the devised architecture utilizes the least means square approach, which enhances the convergence rate notably. [ABSTRACT FROM AUTHOR]

Surface plasmon resonance (SPR) sensors are based on photon-excited surface charge density oscillations confined at metal-dielectric interfaces, which makes them highly sensitive to biological or chemical molecular bindings to functional metallic surfaces. Metal nanostructures further concentrate surface plasmons into a smaller area than the diffraction limit, thus strengthening photon-sample interactions. However, plasmonic sensors based on intensity detection provide limited resolution with long acquisition time owing to their high vulnerability to environmental and instrumental noises. Here, we demonstrate fast and precise detection of noble gas dynamics at single molecular resolution via frequency-comb-referenced plasmonic phase spectroscopy. The photon-sample interaction was enhanced by a factor of 3,852 than the physical sample thickness owing to plasmon resonance and thermophoresis-assisted optical confinement effects. By utilizing a sharp plasmonic phase slope and a high heterodyne information carrier, a small atomic-density modulation was clearly resolved at 5 Hz with a resolution of 0.06 Ar atoms per nano-hole (in 10–11 RIU) in Allan deviation at 0.2 s; a faster motion up to 200 Hz was clearly resolved. This fast and precise sensing technique can enable the in-depth analysis of fast fluid dynamics with the utmost resolution for a better understanding of biomedical, chemical, and physical events and interactions. [ABSTRACT FROM AUTHOR]

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The increasing demand for low voltage, power efficient, high-speed analog-to-digital converters (ADCs) results in the improvement of speed and power of regenerative dynamic comparator. In this paper, a dual-tail dynamic comparator is used with two extra transistors in the latch stage. These extra transistors help in the increase of transconductance of the latch stage, which helps decrease the delay of the proposed comparator. Mathematical analysis is done for the proposed architecture; this gives the idea of reducing the delay of the comparator with an increase in the transconductance of the comparator. The simulation and layout of the proposed comparator are done on the Cadence software with 90 nm CMOS technology. This proposed design is simulated with a 2 GHz clock frequency at supply voltage of 1 V. The proposed architecture consumes a power of 39.19 μ W and a delay of 143.12 ps at 1 V supply voltage, 5 mV input difference voltage and 0.9 V common mode voltage. The Monte Carlo simulation of the proposed architecture for power, delay, power delay product (PDP) and offset is also demonstrated in this paper. Process corner analysis is done for power, delay and PDP. [ABSTRACT FROM AUTHOR]

Electrical machines that can run at high speeds are more and more studied as they can respond to the increasing need of power onboard of aircrafts. However, to allow high-speed operability mechanical handling of the rotating parts need to be insured. In this paper an analytic design process of a novel high-speed induction machine is presented. The analytical magnetic and mechanical models developed are presented and validated with finite element simulations. The magnetic model is based on a classic equivalent electrical diagram of induction machine with a specific adaptation for the rotor leakage inductance as the squirrel cage is buried. The mechanical model is based on a field displacement approach leading to the stress tensor in all the rotating part. A four degrees of freedom vibration analysis model considering gyroscopic effects based on Euler–Lagrange equation allows to identify the critical speeds of the system. It is shown that some geometrical parameters will have opposed effects on the two physics. Thus, an optimization-based coupling between the different physics allows to design rapidly the desired machine regarding any technical specifications as analytical models are being used. [ABSTRACT FROM AUTHOR]

In the domain of high‐performance short‐wave infrared (SWIR) photodetection and imaging, existing technologies predominantly utilize single‐crystal germanium and III‐V semiconductors. Despite their efficacy, these materials are encumbered by laborious synthesis and complex fabrication demands. In this study, the synthesis of large‐area, high‐crystallinity Se0.2Te0.8 thin films through a CMOS‐compatible vacuum thermal evaporation process is reported. A high‐speed, broad‐spectrum photodetector engineered with an innovative Gr/Se0.2Te0.8/GaAs vertical heterostructure is presented, which capitalizes on the augmented carrier mobility and employs graphene innovatively as both a carrier collection interface and an electrode. This configuration facilitates a remarkably swift response time of 800 ns/1 µs at the crucial 1310 nm wavelength for optical communications. Moreover, the fabrication of a 5 × 5 array device demonstrates substantial SWIR imaging capabilities at ambient conditions, marking a paradigm shift in uncooled infrared imaging and communication technologies. This work not only extends the boundaries of SWIR photodetector performance but also underscores the potential of novel material systems in high‐speed optical applications. [ABSTRACT FROM AUTHOR]

We present a novel photon-acid diffusion method to integrate polymer microlenses (MLs) on a four-channel, high-speed photo-receiver consisting of normal-incidence germanium (Ge) p-i-n photodiodes (PDs) fabricated on a 200 mm Si substrate. For a 29 µm diameter PD capped with a 54 µm diameter ML, its dark current, responsivity, 3 dB bandwidth (BW), and effective aperture size at −3 V bias and 850 nm wavelength are measured to be 138 nA, 0.6 A/W, 21.4 GHz, and 54 µm, respectively. The enlarged aperture size significantly decouples the tradeoff between aperture size and BW and enhances the optical fiber misalignment tolerance from ±5 µm to ±15 µm to ease the module packaging precision. The sensitivity of the photo-receiver is measured to be −9.2 dBm at 25.78 Gb/s with a bit error rate of 10−12 using non-return-to-zero (NRZ) transmission. Reliability tests are performed, and the results show that the fabricated Ge PDs integrated with polymer MLs pass the GR-468 reliability assurance standard. The demonstrated photo-receiver, a first of its kind to the best of our knowledge, features decent performance, high yield, high throughput, low cost, and compatibility with complementary metal-oxide-semiconductor (CMOS) fabrication processes, and may be further applied to 400 Gb/s pulse-amplitude modulation four-level (PAM4) communication. [ABSTRACT FROM AUTHOR]

Complementary metal oxide semiconductor (CMOS) comparators play a pivotal role in analog and mixed‐signal circuits, finding diverse applications across electronic systems. In data converter circuits, the significance of high‐speed, low‐power comparators is pronounced. They ensure swift and precise signal comparisons, minimizing energy usage for dependable analog‐to‐digital and digital‐to‐analog conversions. This paper introduces an advanced CMOS dynamic comparator, optimized for data converter circuits using a 45 nm CMOS process. The comparator integrates two novel designs tailored for operation at 0.8 and 1 V power supplies, functioning at 1 GHz. One design incorporates a cascode differential amplifier in the pre‐amplifier stage, enhancing speed and sensitivity by augmenting gain, linearity, and output swing. This approach achieves a delay of 73.53 ps and consumes 9.95 μW at a 1 V supply voltage. The second design employs a simple charge pump in the pre‐amplifier stage, further elevating speed and sensitivity through amplified voltage levels and enhanced slew rate, resulting in a 57.24 ps delay and 9.03 μW power consumption at 1 V. Simulations underscore the proposed comparator's superiority over conventional counterparts, showcasing significant enhancements in speed and power efficiency, all while preserving precision and dependability. [ABSTRACT FROM AUTHOR]

The graphene adjustable-barriers phototransistor is an attractive novel device for potential high speed and high responsivity dual-band photodetection. In this device, graphene is embedded between the semiconductors silicon and germanium. Both n-type and p-type Schottky contacts between graphene and the semiconductors are required for this device. While n-type Schottky contacts are widely investigated, reports about p-type Schottky contacts between graphene and the two involved semiconductors are scarce. In this study, we demonstrate a p-type Schottky contact between graphene and p-germanium. A clear rectification with on–off ratios of close to 103 (±5 V) and a distinct photoresponse at telecommunication wavelengths in the infrared are achieved. Further, p-type silicon is transferred to or deposited on graphene, and we also observe rectification and photoresponse in the visible range for some of these p-type Schottky junctions. These results are an important step toward the realization of functional graphene adjustable-barrier phototransistors. [ABSTRACT FROM AUTHOR]

To clarify the transmission characteristics of a traction drive operating at a high rotational speed, the traction coefficient for an actual drive was measured and was found to decrease by 20% at 50000 rpm. Therefore, a traction model was created to design a roller with a higher traction coefficient. Empirical equations were derived to represent the three characteristic values required for the model. By adjusting the coefficients in the equations to match the measured values of the traction coefficient, the traction coefficient could be predicted with a maximum error of 7% regardless of the conditions. [ABSTRACT FROM AUTHOR]

Abstract Surface plasmon resonance (SPR) sensors are based on photon-excited surface charge density oscillations confined at metal-dielectric interfaces, which makes them highly sensitive to biological or chemical molecular bindings to functional metallic surfaces. Metal nanostructures further concentrate surface plasmons into a smaller area than the diffraction limit, thus strengthening photon-sample interactions. However, plasmonic sensors based on intensity detection provide limited resolution with long acquisition time owing to their high vulnerability to environmental and instrumental noises. Here, we demonstrate fast and precise detection of noble gas dynamics at single molecular resolution via frequency-comb-referenced plasmonic phase spectroscopy. The photon-sample interaction was enhanced by a factor of 3,852 than the physical sample thickness owing to plasmon resonance and thermophoresis-assisted optical confinement effects. By utilizing a sharp plasmonic phase slope and a high heterodyne information carrier, a small atomic-density modulation was clearly resolved at 5 Hz with a resolution of 0.06 Ar atoms per nano-hole (in 10–11 RIU) in Allan deviation at 0.2 s; a faster motion up to 200 Hz was clearly resolved. This fast and precise sensing technique can enable the in-depth analysis of fast fluid dynamics with the utmost resolution for a better understanding of biomedical, chemical, and physical events and interactions.

Electrification is progressing across different fields such as automobiles and construction machinery. Motors for electric systems are required to be compact and achieve high power density. In this study, we developed a small motor with rotation speed of 22,000 r/min by reducing stress concentration. Each pole has three magnets in the circumferential direction, and the magnets are arranged in a U‐shape. The magnet insert slots are comprised of expanded flux barriers on the inner diameter side and a guide‐less structure. The magnet slots reduce stress concentration. Additionally, the rotor has two dents on the outer diameter surface and expanded flux barriers on the outer diameter side. The dents have different shapes between the North (N) and South (S) poles. The structures reduce the torque ripple. [ABSTRACT FROM AUTHOR]

A novel high-speed and process-compatible carrier-stored trench-gate bipolar transistor (CSTBT) combined with split-gate technology is proposed in this paper. The device features a split polysilicon electrode in the trench, where the left portion is equipotential with the cathode. This design mitigates the impact of the anode on the trench gate, resulting in a reduction in the gate-collector capacitance (CGC) to improve the dynamic characteristics. On the left side of the device cell, the P-layer, the carrier-stored (CS) layer and the P-body are formed from the bottom up by ion implantation and annealing. The P-layer beneath the trench bottom can decrease the electric field at the bottom of the trench, thereby improving breakdown voltage (BV) performance. Simultaneously, the highly doped CS layer strengthens the hole-accumulation effect at the cathode. Moreover, the PNP doping layers on the left form a self-biased pMOS. In a short-circuit state, the self-biased pMOS turns on at a certain collector voltage, causing the potential of the CS-layer to be clamped by the hole channel. Consequently, the short-circuit current no longer increases with the collector voltage. The simulation results reveal significant improvements in comparison with the conventional CSTBT under the same on-state voltage (1.48 V for 100 A/cm2). Specifically, the turn-off time (toff) and turn-off loss (Eoff) are reduced by 38.4% and 41.8%, respectively. The short-circuit current is decreased by 50%, while the short-circuit time of the device is increased by 2.46 times. [ABSTRACT FROM AUTHOR]

In this paper, a novel high-speed and energy-efficient 4–2 compressor cell is proposed using carbon nanotube field-effect transistors. The proposed compressor is realized efficiently based on NAND–NOR gates and multiplexers. To estimate the performance of the presented design, simulations are carried out using Synopsis HSPICE under different conditions. The results demonstrate the improvement of the proposed design compared to the best reference designs in terms of delay and energy consumption, by 20–26%, respectively. Also, the susceptibility of the proposed design against the process, voltage, temperature (PVT), and noise variations is examined. It is robust against PVT variations and high amplitude of noises compared with its counterpart. Further, embedding the proposed compressor in an 8 × 8-bit binary multiplier demonstrates that it has better speed and energy consumption with regard to its counterparts. [ABSTRACT FROM AUTHOR]

The high-speed turnout is a key part of railway track infrastructure. A process of wheel-load transition and single-wheel/multi-track contact take place in the turnout area, causing significant wheel-rail interaction. Most high-speed turnouts include movable-point crossings. To investigate the wheel-rail transient rolling contact behaviour in movable-point crossings, a 3D finite element (FE) model of a wheelset rolling over a crossing was introduced. The actual geometrical profile of the wheel and the rails in turnouts, the nonlinear materials, the actual relative motion between the point/wing rail, and the moving postures of the wheelset were considered. The simulated mode shape was compared with the experimental mode shape to verify the wheel-rail coupling model. Precise frictional rolling contact solutions and dynamic response, including wheel-rail force, contact stress, equivalent stress, equivalent plastic strain, and stick-slip distribution of the contact patches, were all studied. After this, the parametric analysis of dynamic wheel-rail contact behaviour was carried out. The simulated results indicate that the proposed explicit finite element method can characterise wheel-rail coupled dynamic interaction and mesoscopic rolling contact behaviour well, and improve the understanding of wheel-rail contact behaviour in the movable-point crossing panel of the high-speed turnouts. [ABSTRACT FROM AUTHOR]

To reduce the power consumption of a TDC in high-speed applications, a TDC architecture applied to SS ADC is proposed to reduce redundant counting. This structure can remove the identical part between two rows of pixel signals in a CMOS image sensor by adjusting the start and stop signal of the TDC, which will reduce the number of flipping of D flip-flops in the TDC. This structure requires the simultaneous readout of two rows of pixels in the high-speed CMOS image sensor. In the 110 nm CMOS process, simulation results show that the designed 5-bit TDC achieves an effective number of bits (ENOB) at 4.72 bits and a figure-of-merit (FOM) at 104.7–162.3 fJ/step, with a power consumption ranging from 60 µW to 93 µW. Compared with traditional counting methods, the proposed TDC can reduce counting power consumption by 30%. [ABSTRACT FROM AUTHOR]

The rail vehicle industry wants to produce vehicles with higher speeds, to maintain and increase its market share. However, when the speed of the vehicle increases, it may have an undesirable effect on ride comfort, in terms of ride dynamics. Recent developments towards lighter and faster vehicles make the problem of ride comfort at higher speeds increasingly important. Focusing on the behavior of flexible rather than rigid body behavior should not be neglected when designing long and light car bodies. There are several approaches to incorporate body flexibility in multibody simulations and they have some superiorities and weaknesses. In this study, an efficient and accurate vertical dynamic model for the ride comfort analysis is developed and implemented in a commercial object-oriented modeling (OOM) software Dymola (2015 FD01) which uses the open-source code Modelica. This model includes car body flexibility with the assembling of a rigid body approach. The developed model is compared to a three-dimensional vehicle model in the commercial Vampire software (Pro V5.50) at different velocities. For the vertical ride comfort analysis, the ISO 2631-1 standard was used for both the developed model and the three-dimensional model. The results are presented as acceleration history and a w r m s —weighted r.m.s (root mean square) of accelerations—as required by the standard. The developed model has shown its feasibility in terms of its efficiency and accuracy for the vertical ride comfort analysis. The accuracy of the model is evidenced by the fact that the car body vibration level at high speeds shows minor differences compared to the results of the Vampire, which is a validated commercial software in the area of rail vehicle dynamics. The approach involving the assembly of rigid bodies is applied for the first time for high-speed trains in dynamical modelling, with flexible car bodies for ride comfort analysis. Furthermore, it can be used for parametrical studies focusing on ride comfort, thereby offering a quite beneficial framework for addressing the challenges of ride comfort analysis in high-speed rail vehicles. Improvements for and analyses of other aspects are also possible, since the optimization and other useful libraries are readily available in Dymola/Modelica. [ABSTRACT FROM AUTHOR]

Medical image compression is vital for preserving image quality and optimizing storage and transmission in healthcare facilities. FPGA design faces challenges in balancing compression ratios, speed, and power consumption. This study proposes a novel approach using the Selfish Herd Optimization (SHO) algorithm to cluster medical image data based on anatomical features. A hybrid deep convolutional neural network generates optimal predictors for each cluster, extracting features from the image data and generating predictions for each pixel based on its neighbors. The proposed system achieves low power and high-speed FPGA design while ensuring reliability and accuracy. Experimental results on Virtex-7 VC709 and Virtex-5QV130FX FPGAs demonstrate impressive improvements, including a 244.08% increase in frequency, 210.04% increase in speed, 200.90% increase in throughput, 61.37% increase in efficiency, and significant reductions in resource utilization and power consumption. This design promises efficient lossless medical image compression with enhanced performance. [ABSTRACT FROM AUTHOR]

Currently, Indonesia has entered a new phase in the development of modern transportation infrastructure, namely high-speed trains initiated by PT Kereta Cepat Indonesia China. The design of the facility operated is an Electrical Multiple Unit (EMU) CR400AF that can drive up to speeds of 350 km / h. Of course, high train speed requires the reliability of railway road infrastructure, including the geometry and components of rail roads. The technical specifications of high-speed rail roads have been regulated in the Minister of Transportation Regulation Number 7 of 2022. The type of rail used by high-speed railway line components with a rail road width of 1435 mm is type R60 rail. However, the determination of the type of high-speed railway in Indonesia has not been completed by analyzing the strength of the rail structure in bearing the load working on it. Thus, this study discusses the influence of rail road geometry on the speed of facilities and evaluates the strength of Type R60 rail structures in receiving high-speed train loads. The analysis method uses the Beam on Elastic Foundation (BOEF) method which assumes the behavior of rails as continuous beams that receive loads on elastic foundation pedestals. The results of the study found that the value of the realized radius and minimum radius of the horizontal arch respectively amounted to 9,500 m and 8,502.94 m greater than the horizontal arch permit radius of 7,000 m, while for the value of the permit radius and vertical radius of the vertical arch of 25,000 m. So that the optimization of the horizontal curved radius to 8,502.94 m to be more in line with the ability of the path to serve passing facilities and is expected to be more effective and efficient in planning. The static load and dynamic load of the EMU wheel CR400AF of 81,662.50 N and 243,522.90 N. The maximum voltage and rail clearance voltage were obtained at 134.53 N/mm2 and 228.57 N/mm2. The strength of the rails is written in the form of a safety factor (SF) number. The calculation results show that the most critical SF value of the rail in receiving the load of high-speed trains is 1.70. Based on the results of BoEF calculations, R60 type rails have a high safety value in withstanding static loads and dynamic loads of high-speed trains. [ABSTRACT FROM AUTHOR]

Developed High speed-rotating machinery is used in agriculture for various processes. This machinery runs using the tractor PTO operated at variable speed. Operating systems of machinery were depends on the skill of the driver. Due to jerks during operation and lack of maintenance such machinery gets fails. To increase the life of rotating components, Ni-Cr based self-lubricating composite bearings were developed and used for the actual application. Self-lubricating composite was tested under the different velocities of 3.14, 3.77, 4.71, and 6.28m/s up to a maximum of 8 Hours. The average wear rate of 7.2%MoS2 content composite is less than the other compositions of Ni-Cr-wt% of MoS2 self-lubricating composite. The result of the actual trial shows that the average wear rate of Ni-Cr- 7.2 wt%MoS2 at velocities 3.14m/s,3.77m/s,4.71m/s, and 6.28m/s is 5.74*10-9mm3/Nm, 6.09*10-9mm3/Nm, 6.30*10-9mm3/Nm, and 6.44*10-9mm3/Nm respectively.

In order to solve the problem of limited driving speed of piezoelectric actuators when the piezoelectric components are small and the driving frequency is low. This paper proposes a bi-directional piezoelectric stick-slip actuator, which mainly utilizes the combination of flexible drive foot and lever amplification mechanism to realize the displacement amplification function, thus improving the driving performance. Firstly describe the structure and working principle of the proposed actuator, and carries out theoretical analysis and mathematical modeling of the flexible stator. Then the driving process of the proposed actuator is simulated and analyzed with COMSOL Multiphysics simulation software, and the feasibility of the driver structure is preliminarily verified. Finally, establish an experimental system to test the basic characteristics of the prototype. The experimental results confirm that under the piezoelectric stacks elongation of $5\mu $ m, the driving frequency of 610Hz, the maximum drive speed of the actuator is 11.21mm/s. The maximum load capacity is 0.78N and the forward and backward displacement deviation within 10 cycles is $0.99\mu $ m under the locking displacement of $10\mu $ m. The proposed stick-slip actuator is capable of realizing a large driving speed when the elongations of the piezoelectric stacks are small and the driving frequency is low.

A bridgeless rotor of a synchronous reluctance machine is proposed to enhance the performance of high-power and -speed synchronous reluctance machines (SynRMs). Unlike traditional transversally laminated designs that rely on radial and tangential ribs or bridges to provide mechanical integrity for the rotor, the suggested rotor incorporates separate flux guides attached to non-magnetic back plates to form SynRM rotor modules that are stacked on the shaft of the machine. This innovative structure eliminates the need for radial and tangential bridges which form a performance-deteriorating bottleneck in the design of high-power SynRMs. The paper presents a detailed analysis of the electromagnetic and mechanical aspects of the proposed bridgeless rotor synchronous reluctance machine (BLRSynRM). Furthermore, a comprehensive optimization method is implemented to demonstrate the capabilities of the proposed BLRSynRM along with comparison with conventional transversally laminated SynRM. The results show a significant increase in torque and power factor compared with conventional structure rotor. However, the proposed bridgeless structure introduces new electromagnetic and mechanical challenges to machine design and they are explained and overcome in this research.

Slotted and slotless stators are two main stator topologies in high-speed permanent magnet brushless direct current (PMBLDC) motors. Both have their own advantages and drawbacks. The electromagnetic loss of slotted and slotless motors have different characteristics in different speed range. Therefore, the comparison of slotted and slotless motors must consider different speed ranges. The performances of slotted and slotless high-speed PMBLDC motors in the full speed range up to 480 krpm are compared in this paper. The no-load and load electromagnetic performances of slotted and slotless motors are studied. The electromagnetic losses of slotted and slotless motors in the full speed range are investigated and compared. Meanwhile, based on the loss calculation results, the thermal characteristics of slotted and slotless motors are studied. The comparison results are summarized considering the electromagnetic, loss and thermal characteristics comprehensively. Finally, a prototype of high-speed PMBLDC motor is manufactured and tested to validate the analysis results.

Industry is increasingly adopting high-speed electric machines due to their high-power density and low cost. However, increasing the speed leads to many challenges that are worth to study since they have relevant impact on the design of the machine. One of these challenges is the losses in stator winding assembly. At low frequency, losses in windings are usually assumed equal to DC losses. However, at high frequency some phenomena become noticeable and worth evaluating since they lead to noticeable losses. AC losses in windings are due to skin effect, proximity effect, and circulating currents. The main models of AC losses in windings in the literature are presented for both circular and rectangular wires. These models are compared using both interior and surface-mounted permanent magnet synchronous machines. Results show that for proximity effect, analytical model is convenient when considering armature reaction only, however, when considering on load case, hybrid model with simple FEA is suitable thanks to its interesting trade-off between accuracy and computation time, which makes it suitable for large-scale optimization. For circulating currents effect, finite element model is unavoidable. Moreover, two important properties concerning circulating currents are stated as well as their mathematical proofs.

The development of modern process CMOS integrated circuits has reduced the feature sizes and thus the reliability of the chip continuously. First, this paper proposed two kinds of single-node upset self-recovery feedback loops with low overhead. One is called P-RFL which is composed of P-type complementary element (CP) and Clocked CP (C2P), and the other is called N-RFL which is composed of N-type complementary element (CN) and Clocked CN (C2N). Second, in order to fully tolerate triple-node upsets (TNUs), this paper presents three TNU-hardened latches: C2P-C2N, DMR-C2P and DMR-C2N. Using the blocking ability of the C-element, the outputs of two RFLs are connected to the C-element array. Therefore, when any three nodes upset at the same time, the transient pulse propagates inside the latch step by step, and disappears after being blocked by the C-element, ensuring that the TNU-hardened latches can restore to the correct logic state. HSPICE simulations show that all the three proposed latches achieve lower power, delay and APDP, compared with other six TNU-hardened latches. DMR-C2N achieves the lowest power, delay and APDP. In addition, the PVT variations analysis show that three proposed TNU-hardened latches are less sensitive to the variations of process, voltage and temperature. [ABSTRACT FROM AUTHOR]

To determine the timing of inflammation in gas and gasoline combustion engines, the point of 10% mass fraction conversion of fuel (MFB10) is commonly used. The MFB10 can be determined from the heating curve, which in turn is calculated from the in-cylinder pressure curve. However, the cylinder pressure is an indirect parameter with regard to inflammation, as it is the result of the combustion that follows the inflammation. An attempt is made to derive a new, direct parameter of inflammation based on optical measurements in order to detect inflammation more rapidly and accurately. The background-oriented Schlieren technique (BOS) in combination with high-magnification optics and a high-speed camera is used to detect local density changes coming from the particle wave around the ignition kernel of a hydrogen combustion inside a combustion chamber. Via BOS and regular high-magnification high-speed imaging, the influence of ignition coil dwell time and in-cylinder pressure on the spark phases and the inflammation itself are evaluated. As a potential direct parameter for inflammation, the size of the particle wave resulting from the expanding ignition kernel is evaluated. It was found that a higher coil energy supports a faster propagation of the particle wave at ambient pressure. At higher pressures, general combustion effects override the effect of the influence of the coil energy on the propagation speed of the particle wave. In addition, the presence of successful inflammation was found to influence the spark phases. A directly measurable parameter for ignition could be found at a basic level, which will serve as a starting point for further detailed investigations. [ABSTRACT FROM AUTHOR]

Forward body biasing (FBB) has often been exploited in the literature for improving the performance of both analog and digital building blocks. Recent works have explored the application of FBB variants to mixed-signal electronics and in particular to dynamic comparators, where these techniques can help to relax the trade-off between speed and power consumption at medium and low supply voltages. However, the literature lacks a structured analysis of the solutions that have been developed and of the trade-offs that affect them. This work attempts to fill the gap by providing a survey of the application of FBB techniques to dynamic comparators. The analysis focuses on the two most popular dynamic comparator topologies, the Strong Arm latch and Elzakker's comparator. Several FBB variants are examined from a theoretical point of view. Moreover, the benefits and the limitations of the different approaches are assessed in terms of the main figures of merit through a systematic campaign of simulations in a 55 nm CMOS technology. [ABSTRACT FROM AUTHOR]

• A novel method modifying suction port based on non-uniform pressure was proposed. • The suction delay was studied with different radial ports and speeds. • The effect mechanism of suction bearing distance was clarified. • Two modified machines with new suction arrangement were tested to prove the method. To improve the efficiency of the twin-screw refrigeration compressor at a high speed of about 3000 rpm, the suction arrangement was investigated in this paper. Several simplified CFD models of a twin-screw refrigeration compressor for chillers were established to parametrically analyze the influence of the suction delay, rotor wrap angle, and suction bearing distance. The parametric studies showed that the volumetric efficiency could be improved by 3 % by a suction delay of 18°, and more volumetric efficiency could be improved by shortening the length of it. The optimal delay angle was found to be linear with the rotational speed. Increasing the wrap angle from 300° to 330°, the volumetric efficiency decreased by 2–3 %, and the adiabatic efficiency increased by about 0.2 %. By increasing the distance between the suction bearings and the rotor end face from 5 mm to 80 mm, the isentropic efficiency increases by about 1.4 %. Based on the parametric studies, two modified machines were built and tested by experiments. Experimental results showed that the volumetric efficiency of machines #1 and #2 increased by 1.5 % at 3000 rpm. The isentropic efficiency of machine #2 increased by 0.78 % at 3000 rpm and 1.27 % at 3300 rpm. [ABSTRACT FROM AUTHOR]

The ongoing study of blast waves and blast wave mitigation continues to play an essential role in protecting structures and personnel. The methodology, however, for capturing far-field blast waves in large-scale tests has remained largely unchanged for three decades, relying on large arrays of pressure transducers connected by hundreds of meters of cabling and requiring a considerable amount of time to set up. This paper evaluates the use of a modern low-cost microprocessor with high computational power to capture blast waves with sufficient fidelity to provide scientists and engineers with credible data. The system utilizes an ARM Cortex M7 processor as an experimental data acquisition (DAQ) system for measuring far-field blast waves in an open-air blast arena at sampling speeds of up to 1.8 Msps (megasamples per second). The experimental system's performance was evaluated by comparing it to a traditional commercial system used for measuring blast waves. The comparison showed an average Spearman correlation coefficient r of 0.928 between the two systems, suggesting a low variance between the commercial and experimental DAQ systems. This suggests that, despite its simplicity, the experimental system is an effective and low-cost alternative for accurately measuring blast waves. [ABSTRACT FROM AUTHOR]

Increased welding speeds are often used to achieve high welding efficiency. However, welding defects, including pores and humps, can easily be formed under high-speed welding conditions. Therefore, a numerical calculation method is proposed to analyze the molten pool dynamic behaviors during high-speed oscillation laser welding with the aluminum alloy. The experiments on high-speed oscillation laser welding are conducted to confirm the simulated results, and both are found to be in good agreement. The distribution characteristics of the temperature field under the condition of a high welding speed are discussed. With the influence of the stirring process from the oscillation laser beam, the temperature gradient is reduced and fluid flow velocity is decreased. The fluid flow in non-oscillation laser welding is more intense than that in oscillation laser welding. It is found that the proposed method can be used to guide the selection of the optimal process parameters for improving welding efficiency and quality in the practical welding process. [ABSTRACT FROM AUTHOR]

Developed High speed-rotating machinery is used in agriculture for various processes. This machinery runs using the tractor PTO operated at variable speed. Operating systems of machinery were depends on the skill of the driver. Due to jerks during operation and lack of maintenance such machinery gets fails. To increase the life of rotating components, Ni-Cr based self-lubricating composite bearings were developed and used for the actual application. Self-lubricating composite was tested under the different velocities of 3.14, 3.77, 4.71, and 6.28m/s up to a maximum of 8 Hours. The average wear rate of 7.2%MoS2 content composite is less than the other compositions of Ni-Cr-wt% of MoS2 self-lubricating composite. The result of the actual trial shows that the average wear rate of Ni-Cr- 7.2 wt%MoS2 at velocities 3.14m/s,3.77m/s,4.71m/s, and 6.28m/s is 5.74*10-9mm³/Nm, 6.09*10-9mm³/Nm, 6.30*10-9mm³/Nm, and 6.44*10-9mm³/Nm respectively. [ABSTRACT FROM AUTHOR]

Serverless computing is a new concept as cloud computing, which dynamically manages the networks and is applied in Serverless Wireless Sensor Networks (SWSN) to help the networks. These networks are becoming famous for monitoring various physical and environmental factors. Serverless computing also facilitates the networks by offering an extensive range of applications. Different applications have been designed for monitoring purposes where the sensor nodes sense the data and transmit it to the base station through single or multi-hop routing. However, existing routing protocols cannot manage the sensor nodes’ energy issues because of the complex routing processes and depleted their power before their time. Because of these limitations, the nodes close to BS continuously rely on the network for data forwarding. As a result, these nodes cause energy consumption and lead to a useless state. This paper proposes a serverless architecture and designs an Enhanced Centroid-based Energy Efficient Clustering (ECEEC) protocol for SWSN networks. The proposed serverless architecture provides automated scalability, cost-effective services, and stateless execution. In addition, the proposed protocol offers the cluster head selection and its rotation to maximize the energy efficiency in the network. Furthermore, gateway nodes are chosen in every cluster to overcome the load on the cluster head. Simulation results indicated the excellent performance of the proposed protocol as compared to the existing routing protocols concerning network lifetime and energy consumption. The proposed protocol shows better reliability with nodes failing at 650 rounds compared to 600 rounds, especially with 5 % and 10 % Cluster Heads. The proposed protocol exhibits superior energy efficiency consumption of SNs under varying CH percentages, indicating the protocol’s consistent performance across different scenarios.

Wire rope breakage, as damage easily produced during the service period of wire rope, is an important factor affecting the safe operation of elevators. Especially in the high-speed elevator operation process, the problem of magnetization unsaturation caused by speed effects can easily lead to deformation of the magnetic flux leakage detection signal, thereby affecting the accuracy and reliability of wire breakage quantitative detection. Therefore, this article focuses on the problem that existing wire rope detection methods cannot perform non-destructive testing on high-speed elevator wire ropes and conducts design and experimental research on a high-speed running wire rope breakage detection device based on the principle of multi-stage excitation. The main research content includes simulation research on the multistage excitation, structural design, and simulation optimization of open–close copper sheet magnetizers and the building of a detection device for wire rope breakage detection experimental research. The simulation and experimental results show that the multistage magnetization method can effectively solve the problem of magnetization unsaturation caused by the velocity effect. The multistage excitation device has a good wire breakage recognition effect for speeds less than or equal to 3 m/s. It can detect magnetic leakage signals with a minimum of four broken wires and has good detection accuracy. It is a new and effective wire breakage detection device for high-speed elevator wire rope, providing important technical support for the safe and reliable operation of high-speed elevators. [ABSTRACT FROM AUTHOR]

In order to meet different operational requirements, existing low specific speed centrifugal pumps may have to be run at high speeds. Therefore, it is crucial to understand the transient performance of such centrifugal pumps during high speed starting and stopping. However, there are currently no experiments on the starting and stopping of low specific speed centrifugal pumps. In this paper, transient hydraulic performance experiments during starting and stopping had been carried out on an atypical open impeller centrifugal pump with a rated flow rate of 6 m3/h using an updated test rig. The correlation of speed, flow, head and shaft power with time was obtained for four flow ratios of 0.353, 1.022, 1.654 and 2.343 operating conditions. It was found that the fluctuation of the shaft power curve was the strongest during the starting process, and there was a significant impact phenomenon. The corresponding impact shaft power from small to large flow rates were 0.167 kW, 0.409 kW, 0.234 kW and 0.215 kW, and the shaft power impact phenomenon was the most obvious under rated operating conditions. During the stopping process, the speed, flow rate and head all remain stable for a small period of time, and the time required to decrease to 0 is longer than the time required to reach a stable state during starting. During stopping, the shaft power will instantly decrease, accompanied by varying degrees of fluctuations. [ABSTRACT FROM AUTHOR]

This paper presents a high-speed level shifter with about 500 V/ns power supply slew immunity. In this designed structure, a narrow pulse-controlled current source is adapted to accelerate the voltage conversion and reduce the power consumption. A Fast-Slewing Circuit speeds up the operation of the level shifter based on the current comparison principle. Edge detection technology is used to filter the generated voltage noise and achieve high dV/dt immunity. The proposed level shifter simulated with the 0.18 μm BCD (bipolar-CMOS-DMOS) process shows fast responses with a typical delay of 1.49 ns and 500 V/ns dV/dt immunity in the 200 V high-voltage application, which only occupies a 0.022 mm2 active area with the 0.18 μm BCD process. [ABSTRACT FROM AUTHOR]

To research serious nonlinear coupling problems among aerodynamics, flight mechanics, and flight control during high maneuvers, a virtual flight testing platform has been developed for a large-scale, high-speed wind tunnel, based on the real physical environment, and it can significantly mitigate risks and reduce the costs of subsequent flight tests. The platform of virtual flight testing is composed of three-degrees-of-freedom model support, measuring devices for aerodynamic and motion parameters, a virtual flight control system, and a test model. It provides the ability to realistically simulate real maneuvers, investigate the coupling characteristics of unsteady aerodynamics and nonlinear flight dynamics, evaluate flight performance, and verify the flight control law. The typical test results of a pitch maneuver with open-loop and closed-loop control are presented, including a one-degree-of-freedom pitch motion and a two-degrees-of-freedom pitch and roll motion. The serious pitch and roll-coupled motion during a pitch maneuver at a high angle of attack is revealed, and the flight control law for decoupled control is successfully verified. The comparison of the test results and the flight data of a real pitch maneuver proves the reliability and capability of virtual flight testing. [ABSTRACT FROM AUTHOR]

On‐chip integration of two‐dimensional (2D) materials holds immense potential for novel optoelectronic devices across diverse photonic platforms. In particular, indium selenide (InSe) is a very promising 2D material due to its ultra‐high carrier mobility and outstanding photoresponsivity. Herein, a high‐speed photodetector based on a multilayer 90 nm thick InSe integrated on a silicon nitride (SiN) waveguide is reported. The device exhibits a remarkable low dark current density of ≈40 nA μm−2, a photoresponsivity of 0.38 A W−1, and an external quantum efficiency of ≈48.4%. Tested under ambient conditions at near‐infrared 976 nm wavelength, it exhibits an absorption coefficient of 0.11 dB μm−1. Additionally, the photodetector demonstrates a 3‐dB radiofrequency bandwidth of 85 MHz and an open‐eye diagram at data transmission of 1 Gbit s−1. Based on these exceptional optoelectronic advantages, integrated multilayer InSe enables the realization of active photonic devices for a range of applications, such as short‐reach optical interconnects, LiDAR imaging, and biosensing. [ABSTRACT FROM AUTHOR]

Nickel titanium shape memory alloys are used in many applications owing to their functional and superior mechanical properties. It is widely accepted in the literature that machining of these alloys is quite challenging. Especially the negative effects of machining on the functional and surface integrity yield potential risks in applications like aerospace and biomedical. In this research, room-temperature-austenitic equiatomic NiTi alloy was surface milled using different cutting tool materials. Cutting speed values between 25 and 400 m/min was employed and effects of these variables on the surface integrity and functional integrity were evaluated. When the cutting speed value was increased over 100 m/min, lesser surface roughness value was observed in most of the cutting tools. The lowest surface quality was achieved with CBN cutting tool at the cutting speed of 400 m/min. The results revealed that in all the machined samples, phase transformation enthalpy decreased and the phase transformation temperature hysteresis increased compared the those of unmachined sample. Accordingly, it was observed that increase of cutting speed resulted in a less effect on transformation enthalpy and hysteresis for all the investigated cutting tool materials. Likewise, it is seen that less subsurface hardening effect was present when the cutting speed was increased. Knowing that as-received material microhardness value is 340 HV, machining with carbide cutting tool at the cutting speed of 25 m/min yielded an increase of 57% on this value at the depth of 20 µm below the cutting surface. [ABSTRACT FROM AUTHOR]