Statistical Channel Modeling for Indoor VLC Communications Based on Channel Measurements

Visible light communication(VLC)has attracted much attention in the research of sixthgeneration(6G)systems.Furthermore,channel modeling is the foundation for designing efficient and robust VLC systems.In this paper,we present extensive VLC channel measurement campaigns in indoor environments,i.e.,an office and a corridor.Based on the measured data,the large-scale fading characteristics and multipath-related characteristics,including omnidirectional optical path loss(OPL),K-factor,power angular spectrum(PAS),angle spread(AS),and clustering characteristics,are analyzed and modeled through a statistical method.Based on the extracted statistics of the above-mentioned channel characteristics,we propose a statistical spatial channel model(SSCM)capable of modeling multipath in the spatial domain.Furthermore,the simulated statistics of the proposed model are compared with the measured statistics.For instance,in the office,the simulated path loss exponent(PLE)and the measured PLE are 1.96and 1.97,respectively.And,the simulated medians of AS and measured medians of AS are 25.94°and 24.84°,respectively.Generally,the fact that the simulated results fit well with measured results has demonstrated the accuracy of our SSCM.

The response of roots and the rhizosphere environment to integrative cultivation practices in paddy rice

Integrative cultivation practices(ICPs)are essential for enhancing cereal yield and resource use efficiency.However,the effects of ICP on the rhizosphere environment and roots of paddy rice are still poorly understood.In this study,four rice varieties were produced in the field.Each variety was treated with six different cultivation techniques,including zero nitrogen application(0 N),local farmers’practice(LFP),nitrogen reduction(NR),and three progressive ICP techniques comprised of enhanced fertilizer N practice and increased plant density(ICP1),a treatment similar to ICP1 but with alternate wetting and moderate drying instead of continuous flooding(ICP2),and the same practices as ICP2 with the application of organic fertilizer(ICP3).The ICPs had greater grain production and nitrogen use efficiency than the other three methods.Root length,dry weight,root diameter,activity of root oxidation,root bleeding rate,zeatin and zeatin riboside compositions,and total organic acids in root exudates were elevated with the introduction of the successive cultivation practices.ICPs enhanced nitrate nitrogen,the activities of urease and invertase,and the diversity of microbes(bacteria)in rhizosphere and non-rhizosphere soil,while reducing the ammonium nitrogen content.The nutrient contents(ammonium nitrogen,total nitrogen,total potassium,total phosphorus,nitrate,and available phosphorus)and urease activity in rhizosphere soil were reduced in all treatments in comparison with the non-rhizosphere soil,but the invertase activity and bacterial diversity were greater.The main root morphology and physiology,and the ammonium nitrogen contents in rhizosphere soil at the primary stages were closely correlated with grain yield and internal nitrogen use efficiency.These findings suggest that the coordinated enhancement of the root system and the environment of the rhizosphere under integrative cultivation approaches may lead to higher rice production.

Experimental Study on Gas Flow Uniformity in a Diesel Particulate Filter Carrier

A Diesel Particulate Filter(DPF)is a critical device for diesel engine exhaust products treatment.When using active-regeneration purification methods,on the one hand,a spatially irregular gas flow can produce relatively high local temperatures,potentially resulting in damage to the carrier;On the other hand,the internal temperature field can also undergo significant changes contributing to increase this risk.This study explores the gas flow uniformity in a DPF carrier and the related temperature behavior under drop-to-idle(DTI)condition by means of bench tests.It is shown that the considered silicon carbide carrier exhibits good flow uniformity,with a temperature deviation of no more than 2%with respect to the same radius measurement point at the outlet during the regeneration stage.In the DTI test,the temperature is relatively high within r/2 near the outlet end,where the maximum temperature peak occurs,and the maximum radial temperature gradient is located between r/2 and the edge.Both these quantities grow as the soot load increases,thereby making the risk of carrier burnout greater.Finally,it is shown that the soot load limit of the silicon carbide DPF can be extended to 11 g/L,which reduces the frequency of active regeneration by approximately 40%compared to a cordierite DPF.

The Correlation between Nutrition and Transport Mechanism under Abiotic Stress in Plants: A Comprehensive Review

Variations in the nutrients and water that plants require for metabolism,development,and the maintenance of cellular homeostasis are the main causes of abiotic stress in plants.It has,however,hardly ever been studied how these transporter proteins,such as aquaporin which is responsible for food and water intake in cell plasma mem-branes,interact with one another.This review aims to explore the interactions between nutrient transporters and aquaporins during water and nutrient uptake.It also investigates how symbiotic relationships influence the plant genome’s responses to regulatory processes such as photoperiodism,senescence,and nitrogenfixation.These responses are observed in reaction to various abiotic stresses.For instance,plasma membrane transporters are upregulated during macronutrient insufficiency,tonoplast transporters are overexpressed,and aquaporins are downregulated in micronutrient deficiency.Additionally,tolerant plants often exhibit increased expression of nutrient transporters and aquaporins in response to drought,salt,and cold temperatures.To better comprehend plant stress tolerance to abiotic challenges including starvation,K famine,salt,and freezing temperatures,both classes of nutrient and water transporters should be considered at the same time.

Optimal Design and Experimental Study of Tightly Coupled SCR Mixers for Diesel Engines

Two types of tightly coupled Selective Catalytic Reduction(SCR)mixers were designed in this study,namely Mixer 1 integrated with an SCR catalyst and Mixer 2 arranged separately.Computational Fluid Dynamics(CFD)software was utilized to model the gas flow,spraying,and pyrolysis reaction of the aqueous urea solution in the tightly coupled SCR system.The parameters of gas flow velocity uniformity and ammonia distribution uniformity were simulated and calculated for both Mixer 1 and Mixer 2 in the tightly coupled SCR system to compare their advantages and disadvantages.The simulation results indicated that Mixer 1 exhibited a gas velocity uniformity of 0.972 and an ammonia distribution uniformity of 0.817,whereas Mixer 2 demonstrated a gas velocity uniformity of 0.988 and an ammonia distribution uniformity of 0.964.Mixer 2 performed better in the simulation analysis.Furthermore,a 3D-printed prototype of Mixer 2 was manufactured and installed on an engine test bench to investigate ammonia distribution uniformity and NOX conversion efficiency.The experimental investigations yielded the following findings:1)The ammonia distribution uniformity of Mixer 2 was measured as 0.976,which closely aligned with the simulation result of 0.964,with a deviation of 1.2%from the model calculations;2)As exhaust temperature increased,the ammonia distribution uniformity gradually improved,while an increase in exhaust flow rate resulted in a decrease in ammonia distribution uniformity;3)When utilizing Mixer 2,the NOX conversion efficiency reached 84.7%at an exhaust temperature of 200°C and 97.4%at 250°C.Within the exhaust temperature range of 300°C to 450°C,the NOX conversion efficiency remained above 98%.This study proposed two innovative mixer structures,conducted simulation analysis,and performed performance testing.The research outcomes indicated that the separately arranged Mixer 2 exhibited superior performance.The tightly coupled SCR systemequippedwith Mixer 2 achieved excellent levels of gas velocity uniformity,ammonia distribution uniformity,and NOX conversion efficiency.These findings can serve as valuable references for the design and development of ultra-low emission after-treatment systems for diesel engines in the field of diesel engine aftertreatment.

Impact of skin sensitivity mechanisms on sebum secretion: Management strategies for oily sensitive skin

Recent epidemiological surveys based on Baumann's classification have revealed a notable rise in the prevalence of oily sensitive skin.The development of oily sensitive skin is primarily linked to the abnormal function of sebaceous glands.The function of sebaceous glands is regulated by several factors,including inflammatory mediators,neurotransmitters,and endocrine signals.Sensitive skin,particularly oily sensitive skin,is prone to local inflammation,which in turn disrupts the normal functioning of sebaceous glands.This creates a loop wherein increased oil production exacerbates sensitivity,while heightened sensitivity further stimulates sebum secretion,perpetuating a vicious cycle.This article summarizes our understanding of the four primary mechanisms underlying skin sensitivity and their impact on sebaceous gland activity.Accordingly,it proposes management strategies for oily sensitive skin and seeks to guide the development of skin care regimens for this skin type.

Design and Research of Active Gravity Unloading Device for Large Aperture Optical Mirror

The large aperture optical mirror for space is processed and tested in the gravity environment on the ground. After entering space, gravity disappears due to the change of environment, and the mirror surface that has met the engineering requirements on the ground will change, seriously affecting the imaging quality. In order to eliminate the influence of gravity and to ensure the consistency of space and ground, gravity unloading must be performed. In order to meet the requirements of processing and testing for the large aperture space mirror in the state of vertical optical axis, a universal gravity unloading device was proposed. It was an active support and used air cylinders to provide accurate unloading force. First, the design flow of gravity unloading was introduced;then the detailed design of the mechanical structure and control system was given;then the performance parameters of the two types of cylinders were tested and compared, including the force-pressure relationship curve and the force-position relationship curve;finally, the experimental verification of the gravity unloading device was carried out;for a mirror with an aperture of ?2100 mm, the gravity unloading device was designed and a vertical detection optical path was built. The test results showed that by using this gravity unloading device, the actual processing surface accuracy of the mirror was better than 1/50λ-RMS, which met the application requirement of the optical system. Thus, it can be seen that using this gravity unloading device can effectively unload the gravity of the mirror and realize the accurate processing and measurement of the mirror surface. .

藏药白脉软膏治疗腰椎间盘突出症的疗效与安全性:一项多中心、随机、双盲、安慰剂对照试验方案

目的:评价白脉软膏在腰椎间盘突出症(lumbar disc herniation)患者中的疗效与安全性。方法:本研究设计了一项前瞻、随机、双盲、安慰剂对照的多中心临床试验方案。计划招募194例患者,按1:1的比例平均分配至试验组和对照组。患者将接受为期14天的白脉软膏或安慰剂的干预,随后进行为期1周的随访。通过视觉模拟评分法(visual analogue scale score)评估疼痛程度,日本骨科协会评估治疗分数(Japanese Orthopedic Association score)评估功能状态,Likert量表将用于评估麻木程度,此外还将记录应急处理的使用和对健康教育的依从情况。安全性评估将包括实验室检查和不良事件记录。讨论:这项试验将首次对白脉软膏在腰椎间盘突出症患者中进行临床疗效和安全性评价。使用安慰剂的优势在于排除因盲法不充分而导致的偏倚。为了避免由研究对象和研究者的主观因素引起的任何偏倚,对于结局评价者、数据管理人员、统计分析人员以及所有相关研究人员都将实施盲法。本试验结果将为腰椎间盘突出症的治疗以及白脉软膏的未来研究方向提供重要依据。

Recent Advances on Challenges and Strategies of Manganese Dioxide Cathodes for Aqueous Zinc-Ion Batteries

Aqueous zinc-ion batteries(AZIBs)are regarded as promising electrochemical energy storage devices owing to its low cost,intrinsic safety,abundant zinc reserves,and ideal specific capacity.Compared with other cathode materials,manganese dioxide with high voltage,environmental protection,and high theoretical specific capacity receives considerable attention.However,the problems of structural instability,manganese dissolution,and poor electrical conductivity make the exploration of high-performance manganese dioxide still a great challenge and impede its practical applications.Besides,zinc storage mechanisms involved are complex and somewhat controversial.To address these issues,tremendous efforts,such as surface engineering,heteroatoms doping,defect engineering,electrolyte modification,and some advanced characterization technologies,have been devoted to improving its electrochemical performance and illustrating zinc storage mechanism.In this review,we particularly focus on the classification of manganese dioxide based on crystal structures,zinc ions storage mechanisms,the existing challenges,and corresponding optimization strategies as well as structure-performance relationship.In the final section,the application perspectives of manganese oxide cathode materials in AZIBs are prospected.

Adversarial Training-Aided Time-Varying Channel Prediction for TDD/FDD Systems

In this paper, a time-varying channel prediction method based on conditional generative adversarial network(CPcGAN) is proposed for time division duplexing/frequency division duplexing(TDD/FDD) systems. CPc GAN utilizes a discriminator to calculate the divergence between the predicted downlink channel state information(CSI) and the real sample distributions under a conditional constraint that is previous uplink CSI. The generator of CPcGAN learns the function relationship between the conditional constraint and the predicted downlink CSI and reduces the divergence between predicted CSI and real CSI.The capability of CPcGAN fitting data distribution can capture the time-varying and multipath characteristics of the channel well. Considering the propagation characteristics of real channel, we further develop a channel prediction error indicator to determine whether the generator reaches the best state. Simulations show that the CPcGAN can obtain higher prediction accuracy and lower system bit error rate than the existing methods under the same user speeds.

Nonreciprocity of energy transfer in a nonlinear asymmetric oscillator system with various vibration states

The nonreciprocity of energy transfer is constructed in a nonlinear asymmetric oscillator system that comprises two nonlinear oscillators with different parameters placed between two identical linear oscillators.The slow-flow equation of the system is derived by the complexification-averaging method.The semi-analytical solutions to this equation are obtained by the least squares method,which are compared with the numerical solutions obtained by the Runge-Kutta method.The distribution of the average energy in the system is studied under periodic and chaotic vibration states,and the energy transfer along two opposite directions is compared.The effect of the excitation amplitude on the nonreciprocity of the system producing the periodic responses is analyzed,where a three-stage energy transfer phenomenon is observed.In the first stage,the energy transfer along the two opposite directions is approximately equal,whereas in the second stage,the asymmetric energy transfer is observed.The energy transfer is also asymmetric in the third stage,but the direction is reversed compared with the second stage.Moreover,the excitation amplitude for exciting the bifurcation also shows an asymmetric characteristic.Chaotic vibrations are generated around the resonant frequency,irrespective of which linear oscillator is excited.The excitation threshold of these chaotic vibrations is dependent on the linear oscillator that is being excited.In addition,the difference between the energy transfer in the two opposite directions is used to further analyze the nonreciprocity in the system.The results show that the nonreciprocity significantly depends on the excitation frequency and the excitation amplitude.

Irrigating with cooler water does not reverse high temperature impact on grain yield and quality in hybrid rice

Rice grain yield and quality are negatively impacted by high temperature stress.Irrigation water temperature significantly affects rice growth and development,thus influencing yield and quality.The role of cooler irrigation water in counteracting high temperature induced damages in rice grain yield and quality are not explored.Hence,in the present study two rice hybrids,Liangyoupeijiu(LYPJ)and IIyou 602(IIY602)were exposed to heat stress and irrigated with water having different temperatures in a splitsplit plot experimental design.The stress was imposed starting from heading until maturity under field-based heat tents,over two consecutive years.The maximum day temperature inside the heat tents was set at 38℃.For the irrigation treatments,two different water sources were used including belowground water with cooler water temperature and pond water with relatively higher water temperature.Daytime mean temperatures in the heat tents were increased by 1.2–2.0℃ across two years,while nighttime temperature remained similar at both within and outside the heat tents.Cooler belowground water irrigation did have little effect on air temperature at the canopy level but decreased soil temperature(0.2–1.4℃)especially under control.Heat stress significantly reduced grain yield(33%to 43%),panicles m^(-2)(9%to 10%),spikelets m^(-2)(15%to 22%),grain-filling percentage(13%to 26%)and 1000-grain weight(3%to 5%).Heat stress significantly increased chalkiness and protein content and decreased grain length and amylose content.Grain yield was negatively related to air temperature at the canopy level and soil temperature.Whereas grain quality parameters like chalkiness recorded a significantly positive association with both air and soil temperatures.Irrigating with cooler belowground water reduced the negative effect of heat stress on grain yield by 8.8%in LYPJ,while the same effect was not seen in IIY602,indicating cultivar differences in their response to irrigation water temperature.Our findings reveal that irrigating with cooler belowground water would not significantly mitigate yield loss or improve grain quality under realistic field condition.The outcome of this study adds to the scientific knowledge in understanding the interaction between heat stress and irrigation as a mitigation tool.Irrigation water temperature regulation at the rhizosphere was unable to counteract heat stress damages in rice and hence a more integrated management and genetic options at canopy levels should be explored in the future.

Human Visual Attention Mechanism-Inspired Point-and-Line Stereo Visual Odometry for Environments with Uneven Distributed Features

Visual odometry is critical in visual simultaneous localization and mapping for robot navigation.However,the pose estimation performance of most current visual odometry algorithms degrades in scenes with unevenly distributed features because dense features occupy excessive weight.Herein,a new human visual attention mechanism for point-and-line stereo visual odometry,which is called point-line-weight-mechanism visual odometry(PLWM-VO),is proposed to describe scene features in a global and balanced manner.A weight-adaptive model based on region partition and region growth is generated for the human visual attention mechanism,where sufficient attention is assigned to position-distinctive objects(sparse features in the environment).Furthermore,the sum of absolute differences algorithm is used to improve the accuracy of initialization for line features.Compared with the state-of-the-art method(ORB-VO),PLWM-VO show a 36.79%reduction in the absolute trajectory error on the Kitti and Euroc datasets.Although the time consumption of PLWM-VO is higher than that of ORB-VO,online test results indicate that PLWM-VO satisfies the real-time demand.The proposed algorithm not only significantly promotes the environmental adaptability of visual odometry,but also quantitatively demonstrates the superiority of the human visual attention mechanism.

Effects of stress-induced ABA on root architecture development:Positive and negative actions

Root architecture development,an agronomic trait that influences crop yield,is regulated by multiple plant hormones.Abscisic acid(ABA)is a stress hormone that responds to multiple stresses,including salt,drought,and cold stress,and modulates various aspects of plant growth and development.In recent years,it has been found that ABA synthesized under mild stress or well-watered conditions can support plant growth and stress resistance by positively regulating root architecture development.In this review,we summarize the molecular,cellular,and organismal basis of ABA homeostasis in the root and how ABA signaling affects root architecture development both as an inhibitor and as an activator.We discuss the implications of these studies and the potential for exploiting the components of ABA signaling in designing crop plants with improved root system development and stress resistance.

Square grid pattern with direction-selective surface discharges in dielectric barrier discharge

A new phenomenon that a filament discharged only once instead of twice in a cycle of the applied voltage is observed in a square grid pattern in a dielectric barrier discharge(DBD)with a larger gas gap,which is named intermittent discharge.Its spatiotemporal dynamics and the formation mechanism are studied by the multiple photomultiplier tubes and an intensified charge-coupled device.Corresponding to the positions of spots in the picture with an exposure time of 40 ms,there are some bright spots(discharge spots)and black spots(non-discharged spots)in the instantaneous image with an exposure time of 10μs(a half cycle of the applied voltage).There are at least two bright spots around one black spot and vice versa.The surface discharges(SDS)can be observed between any two adjacent spots.The intensity of the SDSbetween the bright spot and the black spot is 2.5 times greater than that between two adjacent bright spots,which indicates that the SDSare directional-selective.The intermittent discharge with positive(negative)current polarity changes to that with negative(positive)current polarity,after it sustains up to 14 voltage cycles at the longest.The spatial distribution of the electric field component is calculated through COMSOL software to solve the Poisson equation numerically.It is found that the inhomogeneous distribution of surface electric field is caused by the inhomogeneous distribution of wall charges,which leads to direction-selective SDS.The intermittent discharge is formed by the competition between the direction-selective SDSand volume discharges(VDS)in DBD.This is the reason why the intermittent discharge is generated.

循证护理在急性心肌梗死后心律失常中的效果和对患者焦虑情绪影响体会

目的探讨循证护理方案对急性心肌梗死并心律失常患者的临床治疗效果和负面心理影响。方法将2018年4月-2019年4月在本院接受治疗的90例急性心肌梗死并心律失常患者,随机分为两组,每组45例,对照组给予常规护理方案,观察组给予患者循证护理措施,将两组心理状态及治疗有效率记录和对比。结果观察组抑郁自评表(32.21±1.51)分,焦虑自评表分(32.13±0.34)分均显著低于对照组(P<0.05);观察组患者治疗效果93.33%高于对照组75.56%,差异比较具统计学意义(P<0.05)。结论对急性心肌梗死并心律失常患者患者,给予循证护理措施,能够改善患者心理状态,提升患者临床疗效,具一定临床应用价值。

Implementation of Statistical Analysis to Determine Optimum Ultimate Pit

The ultimate pit may affect other aspects in the life of a mine such as economical, technical, environmental, and social aspects. What makes it even more complex is that most often there are many pits which are economically minable. This calls for a heuristic approach to determine which of these pits is the ultimate pit. This study presents a means of selecting an ultimate pit during design operations of the Hebei Limestone mine. During optimization processes of the mine, many pit shells were created using Whittle Software. Normally, Whittle Software optimizes these processes and assigns a revenue factor of 1 for the ultimate pit. Unfortunately, the pit shells created did not satisfy the criteria with a revenue factor of 1 based on the parameters. As a result of this, statistical analysis was implemented to further understand the relationship, variability, and correlation of the pit shells created (data). Correlation Analysis, K-means++ Analysis, Principal Component Analysis, and Generalized Linear models were used in the analysis of the pit shells created. The results portray a salient relationship of the optimization variables. In addition, the proposed method was tested on Whittle Sample projects which satisfy the selection of ultimate pit selection with a revenue factor of 1. The results show that the proposed model produced almost the same results as the Whittle model with a revenue factor of 1 and was also able to determine the ultimate pit in cases which did not satisfy the Whittle selection criteria.

具有交联结构的热重排聚合物膜的制备及气体分离性能

采用不同摩尔比的9,9’-双[4-(4-硝基-3-羟基苯氧基)苯基]芴(BAHPPF)、3,5-二氨基苯甲酸(DABA)与六氟二酐(6FDA)进行共聚,再经热处理后得到一系列聚酰亚胺(PI)膜和具有交联结构的热重排(TR)聚合物膜。结果表明,随着热处理温度升高,热重排和交联反应同时发生,显著提高了层间距和膜材料对5种气体的渗透性。此外,随着DABA摩尔比增加,PI膜的玻璃化转变温度(T_(g))和热分解温度稍有提升;同时,TR膜材料对H_(2),CO_(2),N_(2),O_(2)和CH_(4)的渗透性和理想选择性也获得了提高。其中,TR-7:3膜表现出了最高的气体渗透性,对H_(2),CO_(2),O_(2),N_(2)和CH_(4)的渗透性分别达到了320.9 Barrers,369.7 Barrers,54.3 Barrers,15.0 Barrers和11 Barrers;同时,TR-7:3和TR-6:4膜对CO_(2)/CH_(4)的理想选择性为33.6和40.6,接近2008年的Robeson上限;而TR-9:1和TR-8:2膜对O_(2)/N_(2)的分离性能则超过了2008年的上限。

The Interdisciplinary Research of Big Data and Wireless Channel: A Cluster-Nuclei Based Channel Model

Recently,internet stimulates the explosive progress of knowledge discovery in big volume data resource,to dig the valuable and hidden rules by computing.Simultaneously,the wireless channel measurement data reveals big volume feature,considering the massive antennas,huge bandwidth and versatile application scenarios.This article firstly presents a comprehensive survey of channel measurement and modeling research for mobile communication,especially for 5th Generation(5G) and beyond.Considering the big data research progress,then a cluster-nuclei based model is proposed,which takes advantages of both the stochastical model and deterministic model.The novel model has low complexity with the limited number of cluster-nuclei while the cluster-nuclei has the physical mapping to real propagation objects.Combining the channel properties variation principles with antenna size,frequency,mobility and scenario dug from the channel data,the proposed model can be expanded in versatile application to support future mobile research.

Moderate wetting and drying increases rice yield and reduces water use, grain arsenic level, and methane emission

To meet the major challenge of increasing rice production to feed a growing population under increasing water scarcity,many water-saving regimes have been introduced in irrigated rice,such as an aerobic rice system,non-flooded mulching cultivation,and alternate wetting and drying(AWD).These regimes could substantially enhance water use efficiency(WUE) by reducing irrigation water.However,such enhancements greatly compromise grain yield.Recent work has shown that moderate AWD,in which photosynthesis is not severely inhibited and plants can rehydrate overnight during the soil drying period,or plants are rewatered at a soil water potential of-10 to-15 k Pa,or midday leaf potential is approximately-0.60 to-0.80 MPa,or the water table is maintained at 10 to 15 cm below the soil surface,could increase not only WUE but also grain yield.Increases in grain yield WUE under moderate AWD are due mainly to reduced redundant vegetative growth;improved canopy structure and root growth;elevated hormonal levels,in particular increases in abscisic acid levels during soil drying and cytokinin levels during rewatering;and enhanced carbon remobilization from vegetative tissues to grain.Moderate AWD could also improve rice quality,including reductions in grain arsenic accumulation,and reduce methane emissions from paddies.Adoption of moderate AWD with an appropriate nitrogen application rate may exert a synergistic effect on grain yield and result in higher WUE and nitrogen use efficiency.Further research is needed to understand root–soil interaction and evaluate the long-term effects of moderate AWD on sustainable agriculture.