A novel low power hybrid cache using GC-EDRAM cells

In a typical embedded CPU, large on-chip storage is critical to meet high performance requirements. However, the fast increasing size of the on-chip storage based on traditional SRAM cells makes the area cost and energy consumption unsustainable for future embedded applications. Replacing SRAM with DRAM on the CPU’s chip is generally considered not worthwhile because DRAM is not compatible with the common CMOS logic and requires additional processing steps beyond what is required for CMOS. However a special DRAM technology, Gain-Cell embedded-DRAM (GC-eDRAM)  [1], [2], [3] is logic compatible and retains some of the good properties of DRAM (small and low power). In this paper we evaluate the performance of a novel hybrid cache memory where the data array, generally populated with SRAM cells, is replaced with GC-eDRAM cells while the tag array continues to use SRAM cells. Our evaluation of this cache demonstrates that, compared to the conventional SRAM-based designs, our novel architecture exhibits comparable performance with less energy consumption and smaller silicon area, enabling the sustainable on-chip storage scaling for future embedded CPUs.     

磨料有序排布电镀砂轮的制备及其把持力研究

为解决电镀砂轮磨削加工中容屑空间不足的问题，采用点胶微粘接的方法制备了磨料有序排布的电镀砂轮，分析了磨料粘接效果和镀层力学性能。通过SEM分析了磨料/镀层/导电胶的结合界面，并进行了干磨削试验。研究结果表明，直径约为磨料粒径40%的胶点可粘接住磨料，单个胶点上粘接多颗磨料的占比小于6%；双脉冲电镀工艺制备的镀层显微硬度大于500HV，表层残余应力小于100MPa，磨料/镀层/导电胶之间的界面贴合紧密，无明显缺陷；砂轮在磨削时没有出现磨料脱落现象。     

Microwave hybrid fast sintering of red clay ceramics

This work aimed to examine the performance of the hybrid sintering of clay ceramic in a microwave furnace, compared to the sintering process in a conventional furnace. The raw materials were subjected to X-ray fluorescence, loss on ignition (LOI), X-ray diffraction, particle size distribution, real specific mass, and thermogravimetric analyses. The red clay ceramic mass was prepared, extruded, pre-sintered in a conventional furnace at 600°C/60 min, and sintered at temperatures between 700 °C and 1100 °C. The sintering conventional (resistive oven) was carried out for 60 min with a heating rate of 10°C/min. In the microwave furnace, the sintering times were 5, 10, and 15 min, with a heating rate of 50°C/min, with a sintering chamber coated with silicon carbide (susceptor). The sintered specimens were characterized according to linear shrinkage, water absorption, apparent porosity, apparent specific mass, X-ray diffraction, Raman spectroscopy analysis, spectroscopy analysis in the ultraviolet and visible regions, microhardness, and scanning electron microscopy. The results showed that microwave sintering promoted an increase in the microhardness and apparent specific mass, and reduction in water absorption and apparent porosity values, due to greater densification in the microstructure. The best results occurred for specimens sintered at 1100°C.     

A novel strategy based on salp swarm algorithm for extracting the maximum power of proton exchange membrane fuel cell

Cell temperature and water content of the membrane have a significant effect on the performance of fuel cells. The current-power curve of the fuel cell has a maximum power point (MPP) that is needed to be tracked. This study presents a novel strategy based on a salp swarm algorithm (SSA) for extracting the maximum power of proton-exchange membrane fuel cell (PEMFC). At first, a new formula is derived to estimate the optimal voltage of PEMFC corresponding to MPP. Then the error between the estimated voltage at MPP and the actual terminal voltage of the fuel cell is fed to a proportional-integral-derivative controller (PID). The output of the PID controller tunes the duty cycle of a boost converter to maximize the harvested power from the PEMFC. SSA determines the optimal gains of PID. Sensitivity analysis is performed with the operating fuel cell at different cell temperature and water content of the membrane. The obtained results through the proposed strategy are compared with other programmed approaches of incremental resistance method, Fuzzy-Logic, grey antlion optimizer, wolf optimizer, and mine-blast algorithm. The obtained results demonstrated high reliability and efficiency of the proposed strategy in extracting the maximum power of the PEMFC.     

Zinc doped Fe2O3 for boosting Electrocatalytic Nitrogen Fixation to ammonia under mild conditions

Artificial nitrogen fixation is emerging as a promising approach for synthesis of ammonia at mild conditions. Inspired by biological nitrogen fixation based on bacteria containing iron, zinc doped Fe₂O₃ nanoparticles are proposed as an efficient and earth abundant electrocatalyst for converting N₂ to NH₃. In neutral media, it achieves a maximum Faradaic efficiency (FE) of 10.4% and a large NH₃ yield rate of 15.1 μg h^?1 mg^?1_cat. at ?0.5 V vs. reversible hydrogen electrode. This catalyst also exhibits excellent selectivity and stability. Theoretical calculations suggest the reaction follows the associative enzymatic mechanism and it has a barrier of as low as 0.68 eV.     

Hydrogel photocatalysts for efficient energy conversion and environmental treatment

Photocatalysts have attracted great research interest owing to their excellent properties and potential for simultaneously addressing challenges related to energy needs and environmental pollution. Photocatalytic particles need to be in contact with their respective media to exhibit efficient photocatalytic performances. However, it is difficult to separate nanometer-sized photocatalytic materials from reaction media later, which may lead to secondary pollution and a poor recycling performance. Hydrogel photocatalysts with a three-dimensional (3D) network structures are promising support materials for photocatalysts based on features such as high specific surface areas and adsorption capacities and good environmental compatibility. In this review, hydrogel photocatalysts are classified into two different categories depending on their elemental composition and recent progresses in the methods for preparing hydrogel photocatalysts are summarized. Moreover, current applications of hydrogel photocatalysts in energy conversion and environmental remediation are reviewed. Furthermore, a comprehensive outlook and highlight future challenges in the development of hydrogel photocatalysts are presented.     

Influence of anode current density on carbon parasitic reactions during electrolysis

In the electro-deoxidation process, carbon parasitic reaction (CO₃^2- + 4e^-=C + 3O^2-) usually occurs when using carbon materials as the anode, which leads to increase of the carbon content in the final metal and decrease of the current efficiency of the process. The aim of this work is to reduce the negative effect of carbon parasitic reaction on the electrolysis process by adjusting anode current density. The results indicate that lower graphite anode area can achieve higher current density, which is helpful to increase the nucleation site of CO₂ bubbles. Most of CO₂ would be released from the anode instead of dissolution in the molten CaCl₂ and reacting with O^2- to form CO₃^2-, thus decreasing the carbon parasitic reaction of the process. Furthermore, the results of the compared experiments show that when the anode area decreases from 172.78 to 4.99 cm², CO₂ concentration in the released gases increases significantly, the carbon mass content in the final metal product decreased from 1.09% to 0.13%, and the current efficiency increased from 6.65% to 36.50%. This study determined a suitable anode current density range for reducing carbon parasitic reaction and provides a valuable reference for the selection of the anode in the electrolysis process.     

Pure and complex nanostructures using poly[bis(triiso‐propylsilylethynyl) benzodithiophene‐bis(decyltetradecyl‐thien) naphthobisthiadiazole], carbon nanotubes and reduced graphene oxide for high‐performance polymer solar cells

Crystallization of poly[bis(triiso‐propylsilylethynyl) benzodithiophene‐bis(decyltetradecyl‐thien) naphthobisthiadiazole] (PBDT‐TIPS‐DTNT‐DT) was investigated in supramolecules based on carbon nanotubes (CNTs) and reduced graphene oxide (rGO) and their grafted derivatives. The principal peaks of PBDT‐TIPS‐DTNT‐DT crystals were in the range 3.50°–3.75°. By grafting the surface of the carbonic materials, the assembling of polymer chains decreased because of hindrance of poly(3‐dodecylthiophene) (PDDT) grafts against π‐stacking. The diameters of CNT/polymer and CNT‐g‐PDDT/polymer supramolecules were 160 and 100 nm. The rGO/polymer supramolecules had the highest melting point (T_m = 282 °C) and fusion enthalpy (ΔH_m = 25.98 J g^?1), reflecting the largest crystallites and the most ordered constituents. Nano‐hybrids based on grafted rGO (276 °C and 28.26 J g^?1), CNT (275 °C and 27.32 J g^?1) and grafted CNT (268 °C and 22.17 J g^?1) were also analyzed. T_m and ΔH_m values were significantly less in corresponding melt‐grown systems. The nanostructures were incorporated in active layers of PBDT‐TIPS‐DTNT‐DT:phenyl‐C₇₁‐butyric acid methyl ester (PC₇₁BM) solar cells to improve the photovoltaic features. The best results were detected for PBDT‐TIPS‐DTNT‐DT:PC₇₁BM:rGO/polymer systems having J_sc = 13.11 mA cm^?2, fill factor 60% and V_oc = 0.71 V with an efficacy of 5.58%. On grafting the rGO and CNT, efficiency reductions were 12.01% (5.58%–4.91%) and 9.34% (4.07%–3.69%), respectively. © 2019 Society of Chemical Industry     

Operation of Rh/Ce0.75Zr0.25O2-δ-ƞ-Al2O3/FeCrAl wire mesh honeycomb catalytic modules in diesel steam and autothermal reforming

The Rh/Ce_0·75Zr_0·25O_2–δ-ƞ-Al₂O₃/FeCrAl structured catalytic blocks of length 10, 20, and 60 mm were prepared and tested in the reactions of steam and autothermal reforming of n-hexadecane. It was found in a series of experiments on hexadecane steam reforming with the catalyst heating solely through the reactor wall that the complete conversion of hexadecane at a furnace temperature below 750 °C was not achieved even at GHSV = 10,000 h⁻¹. Under these conditions, the formation of carbon on the catalyst surface was observed. At the reactor wall temperature of 800 °C, the complete conversion of hexadecane was achieved even in the 10 mm long catalytic block (GHSV = 60,000 h⁻¹), accompanied by the formation of various intermediate light hydrocarbons. To achieve complete conversion of these intermediate compounds (mainly 1-alkenes), it is necessary to carry out the steam reforming reaction at GHSV = 10,000 h⁻¹. At hexadecane autothermal reforming, heat is supplied to the reaction zone by exothermic oxidation reaction, which makes this process more efficient. In experiments with the use of additional external heat supply through the reactor wall, complete conversion of hexadecane occurred at GHSV = 120,000 h⁻¹. To convert all by-products (mainly 1-alkenes) and achieve a nearly thermodynamic equilibrium distribution of the main reaction products (H₂, CO, CO₂), the reaction should be carried out at GHSV = 20,000 h⁻¹. Without external heat supply, hexadecane conversion decreased, while the content of light hydrocarbons in the reaction products increased. An increase in the inlet amount of oxygen helps to compensate the heat losses in the reactor and to increase the efficiency of hexadecane autothermal reforming. The performed experiments allow better understanding of the processes which occur during the steam and autothermal reforming of diesel.     

Cu2O nanowires based p-n homojunction photocathode for improved current density and hydrogen generation through solar-water splitting

Hydrogen generation through solar-water splitting is expected to address the global energy crisis by providing a source for a safer and sustainable alternative fuel. Herein, we report a facile synthesis of Cu₂O nanowires and show that the magnetic field could influence the nanowires’ distribution and alignment. Orientation of nanowires was observed to become more inclined towards the magnetic field lines as the values of full-width at half maximum decreased from 140° to 46.2° with the increase in the field strength. Crystallographic, morphological, optoelectronic, and photoelectrochemical properties of the constructed p-n homojunction were analyzed by using different characterization techniques. A high built-in potential of +0.93 V vs. RHE was observed for a 50 nm layer of n-Cu₂O over p-Cu₂O nanowires that resulted in a significantly high photocurrent density of −7.42 mA/cm². The stability in the photoelectrochemical medium was maintained for 14 h, generating 20 mmol/cm² of H₂.