A performance enhanced Rayleigh Brillouin optical time domain analysis sensing system

Aiming at the problem of large fading noise in Rayleigh Brillouin optical time domain analysis system, a wavelength scanning technique is proposed to enhance the performance of the temperature sensing system. The principle of the proposed technique to reduce the fading noise is introduced based on the analysis of Rayleigh Brillouin optical time domain analysis system. The experimental results show that the signal-to-noise ratio(SNR) at the end of optical fiber with length of 50 m after 17 times wavelength scanning is 5.21 d B higher than that with single wavelength, the Brillouin frequency shift(BFS) on the heated fiber with length of 70 m inserted at the center of sensing fiber can be accurately measured as 0.19 MHz, which is equivalent to a measurement accuracy of 0.19 °C. It indicates that the proposed technique can realize high-accuracy temperature measurement and has huge potential in the field of long-distance and high-accuracy sensing.

Ag3PO4 Microcrystals Synthesized by Room-Temperature Solid State Reaction:Enhanced Photocatalytic Activity and Photoelectronchemistry Performance

Ag3PO4 microcrystals with highly enhanced visible light photocatalytic activity are prepared by a facile and simple solid state reaction at room temperature. The composition, morphology and optical properties of the asprepared Ag3PO4 microcrystMs are characterized by x-ray diffraction, scanning electron microscopy and UV-vis diffuse reflectance spectra. The photocatalytie properties of Ag3PO4 are investigated by the degradation of both methylene blue and methyl orange dyes under visible light irradiation. The as-prepared Ag3PO4 microcrystals possess high photocatalytic oxygen production with the rate of 673μmolh-1g-1. Moreover, the as-prepared Ag3PO4 microcrystals show an enhanced photoelectrochemistry performance under irradiation of visible light.

A phase inversion based sponge-like polysulfonamide/SiO_2 composite separator for high performance lithium-ion batteries

In this work,a sponge-like polysulfonamide(PSA)/SiO_2 composite membrane is unprecedentedly prepared by the phase inversion method,and successfully demonstrated as a novel separator of lithium-ion batteries(LIBs).Compared to the commercial polypropylene(PP) separator,the sponge-like PSA/SiO_2 composite possesses better physical and electrochemical properties,such as higher porosity,ionic conductivity,thermal stability and flame retarding ability.The LiCoO_2/Li half-cells using the sponge-like composite separator demonstrate superior rate capability and cyclability over those using the commercial PP separator.Moreover,the sponge-like composite separator can ensure the normal operation of LiCoO_2/Li half-cell at an extremely high temperature of 90 °C,while the commercial PP separator cannot.All these encouraging results suggest that this phase inversion based sponge-like PSA/SiO_2 composite separator is really a promising separator for high performance LIBs.

A meta-analytic review of the approach-avoidance achievement goals and performance relationships in the sport psychology literature

Purpose： To summarize the approach-avoidance achievement goal and performance in the sport psychology literature.Methods： A total of 17 published studies, two of which provided two samples, were located. Accepted meta-analytic procedures were used with Hedges g as the effect size metric. From the 17 studies, 73 effect sizes were calculated.Results： Results based on a random effects model indicated that the performance goal contrast had the largest facilitative impact on performance followed by the mastery and performance approach goals. Both of the avoidance goals performance and mastery had small non-significant and detrimental effects on performance. The homogeneity statistics revealed significant heterogeneity for the approach and avoidance performance goals. Categorical moderator variables were examined for study sex composition（male, female, or mixed）, mean age of sample（〈18 years or 18 years）, study setting（lab or naturalistic）, and nature of performance variable（objective or subjective）.Conclusion： The performance goal contrast holds value for sport performance research. Contrary to approach-avoidance predictions, the mastery-approach goal and performance effect size was significant and of equal magnitude as the performance approach goal and performance effect size. Thus, future research should closely test the efficacy of both the mastery- and performance contrasts in impacting performance of sport tasks. Last, the significant effect sizes reported in this review are in stark contrast to contemporary meta-analytic findings in education.Differences in the approach-avoidance goals in sport and education relative to performance should be researched further.

Study on seismic performance enhancement in bridges based on factorial analysis

The seismic performance of bridges depends on the ductile behavior of its column, as the deck and other substructural components except pile foundations are normally designed to be elastic to facilitate bridge retrofitting. Codes such as AASHTO, Caltrans, IRC： 112 etc. give guidelines for the seismic performance enhancement of columns through ductile detailing. In the present study, a methodology for the seismic performance enhancement of bridges is discussed by using a ＂Parameter-Based Influence Factor＂ （PIF） developed from factorial analysis. The parameters considered in the factorial analysis are： percentage of longitudinal reinforcement （Pt）, compressive strength of concrete （f＇c）, yield strength of steel （fy）, spacing of lateral ties （5） and column height （/4）. The influence of each parameter and their combination on the limit states considered is estimated. Pushover analysis is used to evaluate the capacity of columns, considering shear failure criteria. A total of 243 （35 combinations） analysis results are compiled to develop ＇PIF＇ used in the performance enhancement process. The study also encompasses other sub-objectives such as evaluating the discrepancies in using the Importance Factor （/） in designing bridges of varied functional importance; and estimating the aspect ratio and slenderness ratio values of bridge columns for its initial sizing.

Thermal performance analysis of building construction with insulated walls in summer days and nights

In the present study,the insulation mechanism of building walls during the summer days and nights is investigated with a realistic approach to enhance their performance.A fiber layer,as a porous medium with air gaps,is used along the wall layers to decrease the energy loss.Meanwhile,the radiation heat flux variation during five days in a row has been considered for each side of the building,and it is tried to reach the optimum values for geometrical factors and find suitable insulation for each side of the building.A lattice Boltzmann method(LBM) based code is developed to simulate the actual chain of the heat transfer which consists of radiation,conduction,forced and natural convection combination within wall layers including fiber porous insulation.The results indicate that for the current insulation model,the effect of natural convection on the heat transfer is not negligible and the existence of the porous layer has caused a positive impact on the heat loss reduction by decreasing the circulation speed.Also,by using the optimum location and thickness for the insulation layer,it is showed that each side of the building has different rates of energy loss during a day,and for the appropriate insulation,they need to be evaluated separately.

Performance enhancement of sandwich panels with honeycomb–corrugation hybrid core

The concept of combining metallic honeycomb with folded thin metallic sheets （corrugation） to construct a novel core type for lightweight sandwich structures is proposed. The honeycomb-corrugation hybrid core is manufactured by filling the interstices of aluminum corrugations with precision-cut trapezoidal aluminum honeycomb blocks, bonded together using epoxy glue. The performance of such hybrid-cored sandwich panels subjected to out-of-plane compression, transverse shear, and three-point bending is investigated, both experimentally and numerically. The strength and energy absorption of the sandwich are dramatically enhanced, compared to those of a sandwich with either empty corrugation or honeycomb core. The enhancement is induced by the beneficial interaction effects of honeycomb blocks and folded panels on improved buckling resistance as well as altered crushing modes at large plastic deformation. The present approach provides an effective method to further improve the mechanical properties of conventional honeycomb-cored sandwich constructions with low relative densities.

Performance enhancement of filled-type solar collector with U-tube

In order to increase the efficiency of solar collector, a methodology is proposed based on the analysis of its influencing factors, such as thermal conductivity of filled layer, structure forms of filled layer and heat loss coefficient. The results of analysis show that the heat transfer between pipes in evacuated tube is one of the most important factors, which can lead to the decrease of the outlet temperature of working fluid. In order to eliminate the negative influence of the heat transfer between pipes, the hollow filled-type evacuated tube with U-tube(HUFET) was developed, and the heat transfer characteristics of HUFET were analyzed by theoretical and experimental studies. The results show that the thermal resistances decrease with the increase of the thermal conductivity of filled layer. When the thermal conductivity is over 10 W/(m·K), the change of thermal resistances is very little.Furthermore, the larger the thermal conductivity of filled layer, the less the rate of the energy transfer between the two pipes to the total energy transfer, which is between the absorber tube and the working fluid. There is a little difference between the efficiencies of HUFET and UFET, with the efficiency of HUFET 2.4% higher than that of UFET. Meanwhile, the validation of the model developed was confirmed by the experiment.

The Subtle Colourings of （Informed） Consent in Performance Enhancement： Implications for Expertise

The analytic method, part of the epistemonic method, provides us with a way to cope with perplexed cases, without even referring to the world out there. We are able to predict all possible variations of consent, and go on forming minimum logical quadripoles, 8-poles, 16-poles, etc., before even trying to make any connection to the world. This way, there are two major outcomes： All possible scenarios are predicted, and, because of that, our ＂logical generator＂ produces scenarios we couldn＇t even think of. Consent is, therefore, neither binary （existence or absence）, nor just a continuum from existence to absence, but a cladistic tree stemming from the basic quadripole ＂existence of consent/not existence of consent/absence of consent/not absence of consent.＂ The complexity increases rapidly when other terms are included; try： ＂existence of informed consent＂ or ＂existence of unintentional consent.＂ More levels develop as we examine relevant terms, such as ＂exposure,＂ ＂protection,＂ or ＂consumption.＂ In our case-study, we shall examine how different aspects of consent are expressed regarding the issue of performance enhancement and consider some implications for the notion of expertise within an SEA （Science of Exceptional Achievement） context. Many different terms may describe the most common situations, namely, ＂uniformed consent,＂ ＂unintentional consent,＂ ＂non-intentional consent,＂ ＂not absence of consent,＂ and also, ＂unintentional exposure,＂ ＂intentional non-protection,＂ and so on. In Greek language, the possible variations are even more （there are two kinds of negation in Greek）. All the aforementioned terms have different ethical consequences. We shall also examine whether doping is an inherent part of expertise attainment.

Performance Enhancement of Single-Phase Immersion Liquid-Cooled Data Center Servers

As the promising cooling method for the next generation of data centers,the internal heat transport mechanism and enhancement mechanism of single-phase immersion liquid-cooled(SPILC)systems are not yet well understood.To address this,a steady-state three-dimensional numerical model is constructed herein to analyze flow and thermal transport capacities in servers using SPILC and traditional air-cooling methods.Moreover,this paper emphasizes the influence of component positioning,and underscores the benefits of optimizing coolant flow distribution using baffles.The results indicate that the SPILC system outperforms the traditional air-cooling approach at the same inlet Reynolds number(Re).When Re=10000,the SPILC method reduces the maximum temperature by up to 70.13%,increases the average convective heat transfer coefficient by287.5%,and provides better overall thermal uniformity in data center servers.Moreover,placing devices downstream of high-power components creates"thermal barriers"and degrades thermal transport for upstream devices due to increased flow resistance.Excessive spacing between high-power devices can lead to the formation of bypass channels,further deteriorating heat transfer.Additionally,the addition of baffles in the inlet section of SPILC systems effectively enhances heat dissipation performance.To maximize the heat dissipation capacity,minimizing bypass channels and optimizing the flow distribution of coolants are crucial.

Synthesis of benzoxazine-based phenolic resin containing furan groups

A novel benzoxazine-based phenolic resin containing furan groups（PFB） was synthesized via simple two-step reactions and the structure of PFB was confirmed by FTIR and ~1H NMR spectra.Differential scanning calorimetry（DSC） showed that the polybenzoxazine cured from PFB had good heat resistance and lower polymerization temperature compared with that of benzoxazine-based phenolic resins.

Green Synthesis of Nitrogen-to-Ammonia Fixation: Past, Present, and Future

The nitrogen(N2)-to-ammonia(NH3)fixation driven by renewable energy has an attractive prospect to relieve the global warming and reduce the consumption of fossil fuels.Ideally,photocatalytic,electrochemical,and photoelectrochemical approaches are developed as the next-generation NH3 synthesis technologies to substitute the Haber–Bosch method.However,the NH3 yield rate of nitrogen reduction reaction(NRR)by green approaches is extremely low,resulting in the current dilemma of NRR and contamination issues.Thus,in this mini review,the past advances on the sustainable NRR are briefly summarized in the three aspects as follows:the selectivity and adjustment of various catalysts,the type of electrolyte/solvent system,and the investigation of reaction conditions.Subsequently,the recent critical activities in the area of sustainable NH3 synthesis are analyzed and discussed deeply,and a perspective for rational and healthy development of this area is provided positively。

A comprehensive review of miniatured wind energy harvesters

Following the current rapid development of the Internet of Things(IoT)and wireless condition monitoring systems,energy harvesters which use ambient energy have become a key part of achieving an energy-autonomous system.Miniature wind energy harvesters have attracted widespread attention because of their great potential of power density as well as the rich availability of wind energy in many possible areas of application.This article provides readers with a glimpse into the state-of-the-art of miniature wind energy harvesters.The crucial factors for them to achieve high working efficiency under lower operational wind speed excitation are analyzed.Various potential energy coupling mechanisms are discussed in detail.Design approaches for broadening operational wind-speed-range given a variety of energy coupling mechanisms are also presented,as observed in the literature.Performance enhancement mechanisms including hydrodynamic configuration optimization,and non-linear vibration pick-up structure are reviewed.Conclusions are drawn and the outlook for each coupling mechanisms is presented.

Significantly enhanced of tungsten diselenide functionalization optoelectronic performance phototransistor via surface

Two-dimensional （2D） layered transition metal dichalcogenides （TMDs） have attracted enormous research interests and efforts towards the development of versatile electronic and optical devices, owing to their extraordinary and unique fundamental properties and remarkable prospects in nanoelectronic applications. Among the TMDs, tungsten diselenide （WSe2） exhibits tunable ambipolar transport characteristics and superior optical properties such as high quantum efficiency. Herein, we demonstrate significant enhancement in the device performance of WSe2 phototransistor by in situ surface functionalization with cesium carbonate （Cs2CO3）. WSe2 was found to be strongly doped with electrons after Cs2CO3 modification. The electron mobility of WSe2 increased by almost one order of magnitude after surface functionalization with 1.6-nm-thick Cs2CO3 decoration. Furthermore, the photocurrent of the WSe2-based phototransistor increased by nearly three orders of magnitude with the deposition of 1.6-nm-thick Cs2CO3. Characterizations by in situ photoelectron spectroscopy techniques confirmed the significant surface charge transfer occurring at the Cs2COB/WSe2 interface. Our findings coupled with the tunable nature of the surface transfer doping method establish WSe2 as a promising candidate for future 2D materials- based optoelectronic devices.

Manipulating the ionic nanophase of Nafion by in-situ precise hybridization with polymer quantum dot towards highly enhanced fuel cell performances

Hierarchical-structure materials hold great promise for numerous applied domains such as fuel cell,sensor,and optic.However,the developments are significantly impeded by the lack of efficient strategy permitting precise and efficient decoration of specific confined space.Here,an in-situ precise hybridization strategy is proposed to efficiently manipulate the nanostructure of membrane nanochannels.Typically,Nafion ionic nanochannels are impregnated with precursors via heat swelling,followed by microwave-assisted condensation to form polymer quantum dot network.The formation of polymer quantum dot network significantly improves the stability and functionality of ionic nanophase(i.e.,ionic nanochannel).This helps hybrid membrane achieving enhanced proton conduction and methanol barrier properties,resulting in over ten times increase in proton/methanol selectivity.These then impart prominent device performances for both hydrogen and methanol fuel cells with the elevation of~100%.Importantly,such function manipulation of ionic nanochannels is achieved with fully maintaining function of backbone nanophase.Besides,the regulation of physical topology and chemical environment of ionic nanochannel also brings optimization of gas and ion separation properties.This facile and versatile strategy may open up a new avenue for decorating confined space of many hierarchical-structure materials.

Optimized Load Balancing Technique for Software Defined Network

Software-defined networking is one of the progressive and prominent innovations in Information and Communications Technology.It mitigates the issues that our conventional network was experiencing.However,traffic data generated by various applications is increasing day by day.In addition,as an organization’s digital transformation is accelerated,the amount of information to be processed inside the organization has increased explosively.It might be possible that a Software-Defined Network becomes a bottleneck and unavailable.Various models have been proposed in the literature to balance the load.However,most of the works consider only limited parameters and do not consider controller and transmission media loads.These loads also contribute to decreasing the performance of Software-Defined Networks.This work illustrates how a software-defined network can tackle the load at its software layer and give excellent results to distribute the load.We proposed a deep learning-dependent convolutional neural networkbased load balancing technique to handle a software-defined network load.The simulation results show that the proposed model requires fewer resources as compared to existing machine learning-based load balancing techniques.

Enhanced performance of ruthenium dye-sensitized solar cell by employing an organic co-adsorbent of N,N'-bis((pyridin-2-yl)(methyl)methylene)-o-phenylenediamine

A pyridine-anchor co-adsorbent of N,N＇-bis（（pyridin-2-yl）（methyl） methylene）-o-phenylenediamine（named BPPI） is prepared and employed as co-adsorbent in dye-sensitized solar cells（DSSCs）. The prepared co-adsorbent could overcome the deficiency of N719 absorption in the low wavelength region of visible spectrum, offset competitive visible light absorption of I_3^-, enhance the spectral responses of the co-adsorbed TiO_2 film in region from 300 nm to 750 nm, suppress charge recombination, prolong electron lifetime, and decrease the total resistance of DSSCs. The optimized cell device co-sensitized by BPPI/N719 dye gives a short circuit current density of 12.98 m A cm^（-2）, an open circuit voltage of 0.73 V,and a fill factor of 0.66 corresponding to an overall conversion efficiency of 6.22% under standard global AM 1.5 solar irradiation, which is much higher than that of device solely sensitized by N719（5.29%）under the same conditions. Mechanistic investigations are carried out by various spectral and electrochemical characterizations.

TiO_(2)-coated LiNi_(0.)9Co_(0.08)Al_(0.02)O_(2)cathode materials with enhanced cycle performance for Li-ion batteries

Ni-rich cathode material is one of the most promising materials for Li-ion batteries in electric vehicles.However,fading capacity,poor cyclic stability and high p H value are still major challenges,which suppress its practical application.In this study,spherical LiNi_(0.)9Co_(0.08)Al_(0.02)O_(2)powders with 0.4 wt%TiO_(2)coating layer were prepared by impregnation-hydrolysis method.Scanning electron microscopy(SEM),high-resolution transmission electron microscopy(HRTEM)and X-ray diffraction(XRD)results show that TiO_(2)is uniformly coated on the surface of LiNi_(0.)9Co_(0.08)Al_(0.02)O_(2)particle and slightly embedded into LiNi_(0.)9Co_(0.08)Al_(0.02)O_(2)particles.After 100 cycles at 2.0 C,0.4 wt%TiO_(2)-coated LiNi_(0.)9Co_(0.08)Al_(0.02)O_(2)electrode delivers much higher discharge capacity retention(77.0%)than the pristine LiNi_(0.)9Co_(0.08)Al_(0.02)O_(2)electrode(63.3%).The excellent cycling performance of 0.4 wt%Ti O_(2)-coated LiNi_(0.)9Co_(0.08)Al_(0.02)O_(2)electrode at a high discharge ratio is due to a TiO_(2)coating layer which can effectively reduce the direct contact between cathode material and electrolyte,suppress the oxidation of electrolyte,improve electrical conductivity of the electrode and increase the stability of the structure.

Durbin test with enhanced detection performance to mismatched signal

This paper deals with the problem of detecting a signal whose amplitude is a scaling factor in the presence of homogeneous Gaussian noise with unknown covariance matrix.Since no uniformly most powerful test exists for the problem at hand,we devise and assess a detection strategy based on the well-known Durbin test design criteria.The closed-form expressions for the probabilities of false alarm and detection of the Durbin test are derived,which show that it bears a constant false alarm rate property against the noise covariance matrix.At the analysis stage,the performance of the new receiver is assessed,also in comparison with some classical adaptive detectors,both in matched and in mismatched signal cases.The results show that the proposed detector achieves a visible performance improvement in the presence of severe steering vector mismatch,while maintaining an acceptable detection loss for matched signal.

Graphene/phosphorene nano-heterojunction:facile synthesis, nonlinear optics, and ultrafast photonics applications with enhanced performance

Owing to its thickness-modulated direct energy band gap, relatively strong light–matter interaction, and unique nonlinear optical response at a long wavelength, few-layer black phosphorus, or phosphorene, becomes very attractive in ultrafast photonics applications. Herein, we synthesized a graphene/phosphorene nano-heterojunction using a liquid phase-stripping method. Tiny lattice distortions in graphene and phosphorene suggest the formation of a nano-heterojunction between graphene and phosphorene nanosheets. In addition, we systematically investigate their nonlinear optical responses at different wavelength regimes. Our experiments indicate that the combined advantages of ultrafast relaxation, broadband response in graphene, and the strong light–matter interaction in phosphorene can be combined together by nano-heterojunction. We have further fabricated two-dimensional(2D) nano-heterojunction based optical saturable absorbers and integrated them into an erbium-doped fiber laser to demonstrate the generation of a stable ultrashort pulse down to 148 fs. Our results indicate that a graphene/phosphorene nano-heterojunction can operate as a promising saturable absorber for ultrafast laser systems with ultrahigh pulse energy and ultranarrow pulse duration. We believe this work opens up a new approach to designing 2D heterointerfaces for applications in ultrafast photonics and other research.The fabrication of a 2D nano-heterojunction assembled from stacking different 2D materials, via this facile and scalable growth approach, paves the way for the formation and tuning of new 2D materials with desirable photonic properties and applications.