AISI 321, an austenitic stainless steel, has high corrosion and temperature resistance, making it useful for aerospace and chemical processing. Cathodic cage plasma nitriding (CCPN) is a versatile ...technique that enhances material surface characteristics. This study aims to investigate the effect of the pulsed duty cycle from 10 % to 60 % on microhardness and tribological properties through CCPN treatment. The X-ray diffraction (XRD) analysis indicates a noticeable shift in the γ-phase towards the lower 2θ angle originating from the expanded austenite phase γN by the lattice expansion at the lowest duty cycle. Nitriding at the lowest duty cycle reduced the average crystallite size from 68 nm (untreated) to 4.5 nm, while increasing the duty cycle led to a decrease in micro-strain. The surface microhardness of the sample that underwent the lowest duty cycle improved to 1288 HV0.01 compared to the untreated sample (210 HV0.01). Moreover, the lowest wear rate is observed for the sample nitrided at a low-duty cycle, which agrees with hardness and strain behavior. The results show that the variable pulsed duty in CCPN can improve the surface hardness and tribological properties of AISI 321, particularly at low-duty cycles.
•Plasma nitriding of austenitic stainless steel AISI 321 in N2: H2 plasma in cathodic cage configuration•Formation of expanded austenitic phase by nitrogen diffusion and thickening of nitrided layer to 7.46 µm at low duty cycle.•Enhancement of surface hardness and wear resistance of AISI 321 at low duty cycle
Here, a simplified predictive torque control strategy based on discrete duty cycle technology is proposed for the voltage source inverter permanent magnet synchronous motor drive system. Combining ...the discrete duty cycle technology, the candidate vectors are synthesised by two adjacent active vectors and zero vectors, and meanwhile, the duty cycles of the two adjacent active vectors and zero vectors are generated directly. Afterwards, an extended control set is constructed to improve the control accuracy of torque and flux. An inverted triangular matrix is constructed to store the duty cycle information, which corresponds to the row and column number of the elements. Also, the inverted triangle matrix is divided into three subregions according to the value of duty ratios. A cost function containing only the stator voltage vector error term is constructed and based on the geometric position of the reference voltage vector, the target region in the inverted triangle matrix is determined and the optimal vector is selected. So, the optimal vector prediction process and the duty cycle calculation process are combined into one, reducing the complexity of obtaining the optimal vector. Finally, the feasibility and effectiveness of the proposed algorithm are verified by experiments.
•The new BTMS has two heat transfer paths, including OHP and liquid cooling plate.•Pulsating flow improves OHP stability through periodic enhanced thermal loads.•Optimal OHP stability lies in 38% or ...62% duty cycles, 0.03–0.05 Hz frequencies.•Stably operating OHP enhances the new system's heat transfer performance.
After a comprehensive review of oscillating heat pipe (OHP) based on battery thermal management system (BTMS), a novel battery liquid-cooling system with a ⊥-shaped OHP is presented to increase the volume utilization efficiency of battery module and the total amount of heat dissipation. The new system retains the heat transfer path of the OHP while incorporating an additional heat dissipation route where the liquid cooling plate is in direct contact with the cells. In this paper, pulsating flow is used to tackle the problem of the OHP failing to operate stably due to the insufficient heat load achieved in the new system. The parametric effects of pulsating flow frequencies, cooling initiation temperatures, and duty cycles on the operational performance of the OHP and the average surface temperature of the battery module (Tb) within the new system were investigated. The results indicate that pulsating flow periodically elevates the heat load on the battery surface, enhancing the OHP working properly. The smaller the pulsating flow frequency, the greater the impact on the temperature fluctuations of the new system. The Tb is lowest when the pulsating flow frequencies range from 0.03 Hz to 0.05 Hz. Beyond a frequency of 0.06 Hz, the OHP cannot operate stably. Additionally, moderately increasing the cooling initiation temperature is beneficial for enhancing the average temperature oscillation amplitude of the OHP. The cooling initiation temperature between 45 °C and 47 °C results in a better Tb. Both pulsating flow duty cycles of 38% and 62% contribute to OHP running effectively. The new system with OHP under optimum pulsating flow condition has the optimal Tb, eventually rising by 17.5 °C, which is a 9.8% decrease in temperature rise compared to the system without OHP. And the battery module's surface temperature uniformity has been improved through a reduction of 1.3 °C in the maximum temperature difference (ΔTmax), amounting to a 17.8% decrease. It has been proved that the improved thermal performance of the new system under pulsating flow is attributed to the stable operation of the OHP.
•Electrochemical deposition of FeCoNiCuZn HEA in aqueous medium has been undertaken.•Duty cycle and pH play a prominent role in deciding characteristics of FeCoNiCuZn.•Surface roughness plays no role ...in deciding any characteristics of HEA thin film.•PC rather than DC electrodeposition leads to better quality HEA thin films.
Low melting point elements are often incompatible with alloy synthesis methods that involve high temperatures, and thus, high entropy alloys containing zinc (Zn) have not been explored much to date, hindering the development of new alloy system investigations. In such cases, electrodeposition can be a useful alternative for the synthesis of multi-component (MCA)/high entropy alloys (HEA) which contain elements with large differences in their melting point and those that cannot be easily synthesized through established conventional/melting-casting routes. Though electrodeposition is an age-old technique, exploration of this synthesis route for fabricating HEAs is recently gaining attention, and more specifically, aqueous medium electrodeposition is still in its infancy. The current work reports a HEA containing Zn, namely, FeCoNiCuZn, through electrodeposition in an aqueous medium utilizing sulfate salts. Electrodeposition was carried out by varying different input parameters, namely, duty cycles (input pulse parameters), pH, and substrate roughness. Through these different input parameters, their effects on the composition, phase, and morphology of the deposited films are a matter of investigation. Observations revealed that the composition of the electrodeposited FeCoNiCuZn thin film is highly dependent on the input pulse parameters and the pH, whereas the substrate roughness played no observable significant role, probably owing to the use of pulsed waveform and the very low film thickness (∼ 500 nm). The compositional characterization of the electrodeposited FeCoNiCuZn showed the presence of a high percentage of Cu (> 50 at.%) at lower duty cycles (< 0.75), whereas higher duty cycle (> 0.75) resulted in FeCoNiCuZn HEAs with all five elements in almost equal proportion. Alternatively, lower pH (≤ 1.5) led to high Cu content in the thin film, whereas higher pH (≥ 2.5) resulted in a multi-elemental deposition.
Conventional model predictive control (MPC) uses a single voltage vector every control cycle which makes the cost function minimized through the enumeration process, which will result in relatively ...high steady-state fluctuation and significant computational overhead. MPC's steady-state performance can be enhanced by adding duty cycle control and generalized double vector control though this increases the complexity of the control algorithm. To enhance the permanent magnet synchronous motor (PMSM) performance while lowering algorithm complexity, an equivalent three-vector-based model predictive current control with duty cycle reconstruction is proposed. This method eliminates the enumeration process and lowers the computational overhead in the modified voltage vector space. The steady-state performance is further enhanced using the three-phase duty cycle reconstruction. The validity and feasibility of the proposed MPC are confirmed by comparing it with a double-vector-based MPC (DV-MPC) and three three-vector-based MPC (TV-MPC).
An all-analogue feedback duty-cycle corrector (DCC) circuit with high precision and frequency is presented to tighten duty cycle into an allowable range and compensate for duty-cycle uncertainties in ...high-speed interfaces. The proposed DCC is employed to calibrate the duty cycle of the clock to reduce the deterministic jitter introduced by the duty-cycle distortion. It extracts the duty-cycle information by a differential duty amplifier detection scheme and corrects the clock distortion by a duty-cycle adjuster through the negative feedback loop. The DCC has improved robustness, correction range and operating frequency as compared with other DCCs. With post-simulated results using 55 nm CMOS technology, the output duty cycle is corrected to 50 ± 0.1% over the input duty-cycle range of 20–80% for 1–5 GHz. It consumes 3.6 mW at 3 GHz using a 1.2 V supply voltage and occupies an area of only 0.00174 mm2.
In this study, H4Ti5O12@CNT ion sieves with an encapsulated structure were fabricated by combining pretreated carbon nanotubes (CNTs) as a template and carbon source, C16H36O4Ti as a titanium source, ...and CH3COOLi as a lithium source. By characterizing and analyzing the pretreated and untreated CNTs, numerous COOH and OH functional groups were introduced into the pretreated CNTs, which improved their dispersion in aqueous solutions and ethanol and facilitated the adsorption of lithium ions. The ion sieves prepared with the precursor roasted at 700 °C showed the best adsorption performance. Moreover, the structural integrity of the ion sieves was not affected by acid washing. For the first adsorption cycle, the ion sieves had a lithium‐ion saturated adsorption capacity of 32.32 mg/g. After five adsorption–desorption cycles, the adsorption capacity only decreased by 5.1% to 30.68 mg/g, which shows that they had good cycling stability.
In this study, H4Ti5O12@CNT composite nanotubes with an encapsulated structure were prepared for use as ion sieves by combining pretreated CNTs as a template and carbon source, C16H36O4Ti as a titanium source, and CH3COOLi as a lithium source; roasting them together at different temperatures; and then washing them with hydrochloric acid to remove the lithium. Roasting and acid washing to remove the lithium were performed at different temperatures and the sample roasted at 700 °C showed the best adsorption performance. Characterization of the specific surface area, scanning electron microscopy, and transmission electron microscopy showed that the structure of the ion sieves was relatively stable and acid washing did not affect their structural integrity. In the first adsorption cycle, the saturation adsorption capacity of the ion sieves was 32.32 mg/g. After five adsorption–desorption cycles, it remained at 30.68 mg/g, exhibiting a reduction of only 5.1%. Therefore, the ion sieves had excellent cycling stability.
Purpose
To identify T1D‐filtering methods, which can specifically isolate various ranges of T1D components as they may be sensitive to different microstructural properties.
Methods
Modified ...Bloch‐Provotorov equations describing a bi‐T1D component biophysical model were used to simulate the inhomogeneous magnetization transfer (ihMT) signal from ihMTRAGE sequences at high RF power and low duty‐cycle with different switching time values for the dual saturation experiment: Δt = 0.0, 0.8, 1.6, and 3.2 ms. Simulations were compared with experimental signals on the brain gray and white matter tissues of healthy mice at 7T.
Results
The lengthening of Δt created ihMT high‐pass T1D‐filters, which efficiently eliminated the signal from T1D components shorter than 1 ms, while partially attenuating that of longer components (≥ 1 ms). Subtraction of ihMTR images obtained with Δt = 0.0 ms and Δt = 0.8 ms generated a new ihMT band‐pass T1D‐filter isolating short‐T1D components in the 100‐µs to 1‐ms range. Simulated ihMTR values in central nervous system tissues were confirmed experimentally.
Conclusion
Long‐ and short‐T1D components were successfully isolated with high RF power and low duty‐cycle ihMT filters in the healthy mouse brain. Future studies should investigate the various T1D‐range microstructural correlations in in vivo tissues.
The growth of thin oxide coatings on the aluminum substrate in water-based sodium tungstate electrolyte by plasma electrolytic oxidation (PEO) is discussed and experimentally illustrated. The growth ...is carried out using a distinctive ultra-low duty cycle pulsed direct current (DC) power supply. During the PEO processing elements present in micro-discharges are identified using standard optical emission spectroscopy (OES) technique. The spectral line shape analysis of the first two hydrogen Balmer lines shows the presence of two types of micro-discharges. Obtained coatings are also characterized with respect to their morphology and chemical and phase composition. It is shown that coatings are composed of Al, O, and W, featuring low roughness and porosity. Partial crystallization of the coatings resulted in identification of WO3, W3O8, and γ-Al2O3 crystalline phases.
•Oxide coatings are formed using ultra-low duty cycle pulsed direct current.•OES revealed the presence of two types of micro-discharges.•Obtained thin oxide coatings possess rather low porosity and roughness.•WO3, W3O8 and γ-Al2O3 phases are identified in the coatings.
In the recent HBM2E IO design, clock is transmitted differentially to the external DRAM and duty cycle distortion (DCD) could add to the differential clock due to traversing multiple stages in DRAM. ...At higher data rates, the DCD from the differential clock imposes restrictions on the timing margins. In the current work, Tx clock path is added with DCC feature to compensate for any DCD errors introduced by the clock network in the external DRAM. Linearity of the DCC is critical metric when the clock is differential and running at high speed. A new programmable delay line with inherent DCC design with good linearity is presented in this paper.
