FreestandingMo_(3)N_(2) nanotubes for long-term stabilized 2e−intermediate-based high energy efficiency Li-CO_(2) batteries

Li–CO_(2) batteries are considered one of the promising power sources owing to ultrahigh energy density and carbon fixation.Nevertheless,the sluggish reaction kinetics of 4e−discharged process(Li_(2)CO_(3))impede its potential application.One of the efficient strategies for developing cathode catalysts is to stabilize 2e−intermediate Li_(2)C_(2)O_(4) and improve reaction reversibility.However,longterm catalysts of stabilized Li_(2)C_(2)O_(4) are barely achieved,whereas cycle stability is far from satisfactory level.Herein,non-noble metal–based Mo_(3)N_(2) is synthesized and employed as freestanding cathodes for Li–CO_(2) batteries.Owing to rich delocalized electrons of Mo^(2+)and reversible electron localization structure,freestanding Mo_(3)N_(2) cathodes exhibit a low charge potential(3.28 V)with an ultralow potential gap(0.64 V),high energy efficiency of up to 80.46%,fast rate capability,and outstanding cycle stability(>910 h).In situ experiments and theoretical calculation verify that Mo_(3)N_(2) stabilizes 2e−Li_(2)C_(2)O_(4) intermediate by the interaction of Mo^(2+)as active sites where Mo^(2+)promotes the transfer of outer electrons to O,prevents its disproportionation to Li_(2)CO_(3),and promotes reaction kinetics,contributing to high energy efficiency and outstanding cycle reversibility.In addition,the pouch-cells deliver ultrahigh energy density of up to 6350.7W h kg^(−1) based on the mass of cathode materials.

Chloroplast-like porous bismuth-based core–shell structure for high energy efficiency CO2 electroreduction

Electrochemical CO2 reduction reaction(CO2RR)to formate is economically viable considering the energy input and market value.Through learning nature,a series of chloroplast-like porous bismuth-based core–shell(CPBC)materials have been designed.In these materials,the porous carbon can enrich and transfer CO2 to the core–shell Bi@Bi2O3 in CO2 reduction process,during which Bi2O3 layer can be transformed into activated metastable layer to efficiently convert CO2 into formate and Bi can provide abundant electrons.Based on this,superior performances for most of important parameters in CO2 RR can be achieved and best of them,CPBC-1 presents remarkable Faradaic efficiency(FEformate>94%)over a wide potential range(-0.65 to-1.0 V)with high catalysis durability(>72 h).Noteworthy,its maximum energy efficiency is as high as 76.7%at-0.7 V,the highest one in reported bismuth-based materials.This work opens novel perspectives in designing nature-inspired CO2RR electrocatalysts.

Evaluation of Radon Indoor Pollution Risk in High Efficiency Energy Buildings

The target of achieving high energy efficiency standard in order to comply with the EU Directives is leading to remarkable efforts to improve the performance of the building envelope. Excellent thermal insulation and airtight sealing of leakages are of the utmost importance to fulfil the expected targets. Unfortunately, airtightness produces the negative effect of increasing the indoor concentration of air pollutants like radon. Despite the seriousness of the problem is generally misconceived, long-term exposition to radon is acknowledged to be the second cause of lung cancer after smoke. The paper outlines the implications for the building sector and focuses on design and preventive criteria as well as on mitigation and remedial techniques.

Progress in octahedral spherical hohlraum study

In this paper,we give a review of our theoretical and experimental progress in octahedral spherical hohlraum study.From our theoretical study,the octahedral spherical hohlraums with 6 Laser Entrance Holes(LEHs)of octahedral symmetry have robust high symmetry during the capsule implosion at hohlraum-to-capsule radius ratio larger than 3.7.In addition,the octahedral spherical hohlraums also have potential superiority on low backscattering without supplementary technology.We studied the laser arrangement and constraints of the octahedral spherical hohlraums,and gave a design on the laser arrangement for ignition octahedral hohlraums.As a result,the injection angle of laser beams of 50°-60°was proposed as the optimum candidate range for the octahedral spherical hohlraums.We proposed a novel octahedral spherical hohlraum with cylindrical LEHs and LEH shields,in order to increase the laser coupling efficiency and improve the capsule symmetry and to mitigate the influence of the wall blowoff on laser transport.We studied on the sensitivity of the octahedral spherical hohlraums to random errors and compared the sensitivity among the octahedral spherical hohlraums,the rugby hohlraums and the cylindrical hohlraums,and the results show that the octahedral spherical hohlraums are robust to these random errors while the cylindrical hohlraums are the most sensitive.Up till to now,we have carried out three experiments on the spherical hohlraum with 2 LEHs on Shenguang(SG)laser facilities,including demonstration of improving laser transport by using the cylindrical LEHs in the spherical hohlraums,spherical hohlraum energetics on the SGIII prototype laser facility,and comparisons of laser plasma instabilities between the spherical hohlraums and the cylindrical hohlraums on the SGIII laser facility.

Flow-rate Characteristics Measurement of Regulators Based on the Pressure Response in an Isothermal Tank

Regulators are important components in pneumatic system, and their flow-rate characteristics are the key parameters for designers. According to the correlatively international standard and national standard of China, which describe the flow-rate characteristics measurement method of pneumatic regulators, the pressure and the flow are measured point by point, and then the flow-rate characteristics curve is plotted point to point. This method has some disadvantages, such as equipment complexity, much air consumption, and low efficiency. To settle the problems presented above, this paper puts forward a new high efficient and energy saving flow-rate characteristics measurement method of regulators, which is based on the pressure response when charging and discharging to an isothermal tank without any flow meters. The measurement principle, the system and the steps are introduced. And the tracking differentiator is used for the data processing of the pressure difference. Two typical kinds of regulators were experimentally investigated, and their flow-rate characteristics curves were obtained with the new and the conventional method, respectively. Comparatively, it＇s proved that this new method is feasible because it is not only able to meet the demand of the measurement precision, but also to save energy and improve efficiency. Compared to the conventional method, the new method takes only about 1/10 amount of time and consumes about only 1/30 amount of air. Hopefully it will be able to serve as an international standard of flow-rate characteristics measurement method of regulators.

Effects of a flexible net barrier on the dynamic behaviours and interception of debris flows in mountainous areas

Flexible net barriers are a new type of effective mitigation measure against debris flows in valleys and can affect the kinematic energy and mass of debris flows. Here, ten flume tests were performed to study the dynamic behaviours of debris flows with differences in volumes, concentrations(solid volume fraction), and travel distances after interception by a uniform flexible net barrier. A high-speed camera was used to monitor the whole test process, and their dynamic behaviours were recorded. A preliminary computational framework on energy conversion is proposed according to the deposition mechanisms and outflow of debris flow under the effects of the flexible net barrier. The experimental results show that the dynamic interaction process between a debris flow and the flexible net barrier can be divided into two stages:(a) the two-phase impact of the leading edge of the debris flow with the net and(b) collision and friction between the body of the debris flow and intercepted debris material. The approach velocity of a debris flow decreases sharply(a maximum of 63%) after the interception by the net barrier, and the mass ratio of the debris material being intercepted and the kinetic energy ratio of the debris material being absorbed by the net barrier are close due to the limited interception efficiency of the flexible net barrier, which is believed to be related to the flexibility. The energy ratio of outflow is relative small despite the large permeability of the flexible net barrier.

An energy-efficient reconfigurable asymmetric modular cryptographic operation unit for RSA and ECC

RSA and ellipse curve cryptography(ECC)algorithms are widely used in authentication,data security,and access control.In this paper,we analyze the basic operation of the ECC and RSA algorithms and optimize their modular multiplication and modular inversion algorithms.We then propose a reconfigurable modular operation architecture,with a mix-memory unit and double multiply-accumulate structures,to realize our unified,asymmetric cryptosystem structure in an operational unit.Synthesized with 55-nm CMOS process,our design runs at 588 MHz and requires only 437801µm2 of hardware resources.Our proposed design takes 21.92 and 23.36 mW for 2048-bit RSA modular multiplication and modular inversion respectively,as well as 16.16 and 15.88 mW to complete 512-bit ECC dual-field modular multiplication and modular inversion respectively.It is more energy-efficient and flexible than existing single algorithm units.Compared with existing multiple algorithm units,our proposed method shows better performance.The operation unit is embedded in a 64-bit RISC-V processor,realizing key generation,encryption and decryption,and digital signature functions of both RSA and ECC.Our proposed design takes 0.224 and 0.153 ms for 256-bit ECC point multiplication in G(p)and G(2^(m))respectively,as well as 0.96 ms to complete 1024-bit RSA exponentiation,meeting the demand for high energy efficiency.