On the System Performance of Mobile Edge Computing in an Uplink NOMA WSN With a Multiantenna Access Point Over Nakagami-m Fading

In this paper,we study the system performance of mobile edge computing(MEC)wireless sensor networks(WSNs)using a multiantenna access point(AP)and two sensor clusters based on uplink nonorthogonal multiple access(NOMA).Due to limited computation and energy resources,the cluster heads(CHs)offload their tasks to a multiantenna AP over Nakagami-m fading.We proposed a combination protocol for NOMA-MEC-WSNs in which the AP selects either selection combining(SC)or maximal ratio combining(MRC)and each cluster selects a CH to participate in the communication process by employing the sensor node(SN)selection.We derive the closed-form exact expressions of the successful computation probability(SCP)to evaluate the system performance with the latency and energy consumption constraints of the considered WSN.Numerical results are provided to gain insight into the system performance in terms of the SCP based on system parameters such as the number of AP antennas,number of SNs in each cluster,task length,working frequency,offloading ratio,and transmit power allocation.Furthermore,to determine the optimal resource parameters,i.e.,the offloading ratio,power allocation of the two CHs,and MEC AP resources,we proposed two algorithms to achieve the best system performance.Our approach reveals that the optimal parameters with different schemes significantly improve SCP compared to other similar studies.We use Monte Carlo simulations to confirm the validity of our analysis.

Comparisons of Three Recurrent Selection Methods in the Improvement of Maize Populations

The maize population Csyn 4 was improved for three cycles with three recurrent selection methods MS1, MS1-HS, and MHSRRS in northern China. A total of 40 NC Ⅱ testcrosses were made by four testers with Csyn 4 and 10 improved populations, which were evaluated in four environments in the cropping season of 2005. Analysis of variance indicated a significant progress （P〈 0.05） in yield and other chief agronomic traits in the improved populations and testcrosses, demonstrating that the three recurrent selection methods were effective for increasing grain yield of testcrosses and improvement of general combining ability in maize population. The average grain yield increase of population Csyn 4 in MS1, MS1-HS, and MHSRRS recurrent selections was 266.7 kg ha^-1 （5.3%）, 288.0 kg ha^-1 （5.7%）, and 231.3 kg ha^-1 （4.6%） per cycle, while the grain yield of S 1 progeny of population for Csyn 4 was increased by 420.0 kg ha^-1 （10.9%）, 376.0 kg ha^-1 （9.8%）, and 414.7 kg ha^-1 （10.8%） per cycle in MS1, MS1-HS, and MHSRRS recurrent selections, respectively. Linear responses （b） in the MS1, MS1-HS, and MHSRRS recurrent selections were the same as the realized responses of the selection （G） for grain yield increase of Csyn 4 and S1 progeny of the populations. The grain yield of testcrosses increased by 3.3-5.2% on average per cycle. The value of heterosis did not display any differences amongst the different cycles of selections. The GCA for yield component traits of population Csyn 4 was improved significantly by means of three selection methods, whereas the GCA for plant height, ear height, days to silking, and days to pollen did not show significant increase in the recurrent selections. GCA for the number of tassel branches were decreased in the selections, while GCA for the number of plant leaves were increased, but the difference was not significant.

Effects of threshold based relay selection algorithms on the performance of an IEEE 802.16j mobile multi-hop relay （MMR） WiMAX network

IEEE 802.16j MMR WiMAX network introduces multi-hop relay architecture, which involves cooperative relay stations focusing on increasing the network throughput and coverage. Relay selection algorithms can be used to choose the optimal relay, which help in reducing the computational complexity during the signal processing operation of the wireless network. In this research work, a conventional Amplify-Forward （AF）/Decode-Forward （DF） assisted multi-relay IEEE 802.16j WiMAX network is considered. The effects of relay selection algorithms on the performance metrics such as Symbol Error Rate （SER） and channel capacity are investigated in detail through simulation-based study. Further, the performance of this network utilizing the proposed relay selection algo- rithms, namely threshold based max_rain and threshold based harmonic mean of SNR, are compared with the existing max_rain and harmonic mean of SNR based algorithms. Standard diversity combining techniques such as Maximal Ratio Combining （MRC） and Selection Combining （SC） are used for combining the transmitted signal at the receiver. In addition, the impact of relay locations on the performance metrics are explored. It is observed that both the proposed threshold based max_min and threshold based harmonic mean of SNR based relay selection algorithms outperform the max_rain and harmonic mean of SNR based algorithms, as both the SER and channel capacity for the considered multi-relay WiMAX network is improved significantly. Further, this extensive study and analysis will be beneficial for the design of MMR WiMAX networks.

Outage Probability of Composite Microscopic and Macroscopic Diversity over Correlated Shadowed Fading Channels

The outage probability of a composite microscopic and macroscopic diversity system is evaluated over correlated shadowed fading channels.The correlations on both a microlevel and macrolevel are taken into account for the evaluations.The expression of the desired outage probability is explicitly presented,and two evaluation approaches,i.e.a compact Gaussian-Hermite quadrature method and an effective iterative algorithm,are proposed.The accuracy and efficiency of the proposed approaches are analysed,and a guideline is provided for their application.By employing the proposed evaluation approaches,results and demonstrations are presented,which display the implied effects of the corresponding parameters on the system outage performance,and reveal the potential to facilitate the design and analysis of such composite diversity systems.

Capacity and outage probability analysis of downlink MRT-SC in distributed antenna system

This paper investigates the downlink capacity distribution and the outage probability of the interested area of maximum ratio transmission-selection combining(MRT-SC) scheme in the distributed antenna system(DAS).Composite fading channels are assumed,which include path loss,lognormal shadowing and multi-path Rayleigh fading.Analytical approximations of the capacity's cumulative distribution function(CDF),the outage capacity,the mean capacity,and the outage probability of the interested area are derived by means of moment generation function(MGF) and Gauss-Hermite series expansion based approaches.The influence of antenna number,path loss exponent,and shadowing standard deviation on the capacity distribution are investigated.The simulation results agree with the analytical approximations well,and thus the analytical approximations are able to substitute the time-intensive Monte Carlo simulation for further investigation.

PERFORMANCE ANALYSIS OF TAS/MRC-BASED SCHEME IN TIME-VARYING RAYLEIGH FADING CHANNELS

This paper investigates a Multiple-Input Multiple-Output (MIMO) scheme combining Transmit Antenna Selection and receive Maximal-Ratio Combining (TAS/MRC) in time-varying Rayleigh fading channels. We first present new closed-form expressions for optimal received Signal-to-Noise Ratio (SNR),which is expressed in polynomial form. These are used to analyze ergodic capacity,outage probability and Bit Error Rate (BER) of TAS/MRC systems. Numerical results are presented to validate the theoretical analysis.

COMMENTS ON THE STUDY OF ACUPOINT COMBINATION AND REMEDIES FOR TREATMENT OF DIABETES MELLITUS WITH ACUPUNCTURE AND MOXIBUSTION

In the present paper, the author reviews the progresses in the study on acumoxi (acupuncture-moxi-bustion) treatment of diabetes mellitus (DM) from Chinese ancient classical works, Chinese and foreign journals. The therapeutic results reveal that acupuncture treatment of DM is effective in improving DM patients' symptoms via vagal-nerve reflex, regulation of neuroendocrine and immune functions. The author holds that ① correct selection of acupoints in accordance with syndrome differentiation and the related meridians and combined application of acupuncture and Chinese herbal medicines (for oral administration) are the key points for raising the therapeutic effect; and ② acupoint combination and curative methods need to be researched further.

N_2O Decomposed by Discharge Plasma with Catalysts

A great deal of attention has been focused on discharge plasma as it can rapidly decompose N2O without additives,which is not only a kind of greenhouse gas but also a kind of damages to the ozone layer.The thermal equilibrium plasma is chosen to combine with catalysts to decompose N2O,and its characteristics are analyzed in the present paper.The results indicate that NO and NO2 were formed besides N2 and O2 during N2O decomposition when N2O was treated merely by discharge plasma.Concentration of NO declined greatly when the discharge plasma was combined with catalysts.Results of Raman spectra analysis on CeO2,Ce（0.75）Zr（0.25）O2and Ce（0.5）Zr（0.5）O2 imply that the products selectivity has been obviously improved in discharge plasma decomposing N2O because of the existence of massive oxygen vacancies over the composite oxide catalysts.

Selection of surgical methods for thoracic ossification of ligamentum flavum combined with cervical spondylotic myelopathy

Objective To investigate the difference between different surgical methods for thoracic ossification of ligamentum flavum(OLF) combined with cervical spondylotic myelopathy(CSM) . Methods From January 1991 to January 2003,56 cases

Science Letters:Average SNR of maximum ratio transmission with selection combining

Two kinds of selection combining schemes including generalized selection combining (GSC) and generalized order selection combining (GOSC) are investigated. In the GSC scheme, L strongest diversity branches from a total of R diversity branches are selected and coherently combined by maximal ratio combining. GOSC means that the Lth strongest diversity branch from R diversity branches is selected for reception. Closed-form expressions for the average signal-to-noise ratios of maximum ratio transmission with GSC and GOSC are derived in Rayleigh fading channels.

Secrecy outage analysis on underlay cognitive radio using selection combining

Secure data transmission in future high-capacity high-coverage multi-tier hierarchical networks, for which cognitive radio （CR） has emerged as an essential recipe, is of utmost importance. This paper investigates the secrecy outage performance of selection combining （SC） in CR networks （CRNs） over Rayleigh fading channels. In a single-input multiple-output （SIMO） wiretap channel, a secondary user transmits confidential messages to another secondary user, which is equipped with n B （nB ≥1） antennas. Meanwhile, a passive eavesdropper, which is equipped with nE （n E ≥1） antennas, intends to overhear the messages. Both the legal receiver and the eavesdropper adopt SC scheme to process the received multiple signals. The secondary transmitter uses the underlay strategy to guarantee the quality of service of the primary user without spectrum sensing. Compared to the work proposed by Maged Elkashlan et al. in Ref. [ 1 ], we present an alternative method to derive the closed-form expression for the secrecy outage probability （SOP） and develop a simplified SOP when the maximal transmit power at the secondary user is sufficiently high. Our results reveal the impact of the primary network on the secondary network with a multi-antenna wiretap channel and simulations are conducted to validate the accuracy of our proposed analytical models.

Ergodic secrecy capacity of MRC/SC in single-input multiple-output wiretap systems with imperfect channel state information

This paper investigates the secrecy performance of maximal ratio combining （MRC） and selection combining （SC） with imperfect channel state information （CSI） in the physical layer. In a single-input multiple- output （SIMO） wiretap channel, a source transmits confidential messages to the destination equipped with M antennas using the MRC/SC scheme to process the received multiple signals. An eavesdropper equipped with N antennas also adopts the MRC/SC scheme to promote successful eavesdropping. We derive the exact and asymptotic closed-form expressions for the ergodic secrecy capacity （ESC） in two cases： （1） MRC with weighting errors, and （2） SC with outdated CSI. Moreover, two important indicators, namely high signal-to-noise ratio （SNR） slope and high SNR power offset, which govern ESC at the high SNR region, are derived. Finally, simulations are conducted to validate the accuracy of our proposed analytical models. Results indicate that ESC rises with the increase of the number of antennas and the received SNR at the destination, and fades with the increase of those at the eavesdropper. Another finding is that the high SNR slope is constant, while the high SNR power offset is correlated with the number of antennas at both the destination and the eavesdropper.

A Novel Strategy of Multi-element Nanocomposite Synthesis for High Performance ZnO-CoSe_(2) Supercapacitor Material Development

Developing multi-eleme nt composites is a promisi ng way for high perform a nee supercapacitor material developme nt,and simplifying the synthesis steps is critical for reducing the preparation costs and successful promotion of the materials.A novel one-step selective reaction strategy is developed,and successfully used to prepare four-element ZnO-CoSe_(2)(ZOCS)nano-spherical composites,to be used as supercapacitor materials.Started form nano-spherical glycerate templates,under the optimal synthesis condition,the obtained ZOCS-0.125 electrode material exhibits a specific capacitance of 450.7 F/g at 1 A/g and a good rate performance by keeping 76.8%capacitance at 20 A/g.Moreover,the ZOCS-0.125 electrode exhibits excellent cycle stability of 114.9%capacitance retention after 5000 cycles at 10 A/g.An asymmetric supercapacitor assembled by ZOCS-0.125 and activated carbon electrodes delivers an energy density of 22.35 Wh/kg at 825 W/kg,and a cycle stability of 105.6%capacitance retention after 5000 cycles.This work not only shows the good potential of the facilely prepared ZnO-CoSe_(2) composite electrode material,but also dem on strates a new strategy for low cost and high performance multielement composite material development,that can be used in a wide range of applications.

Selection of proper combine harvesters to field conditions by an effective field capacity prediction model

Farmers have to finish their harvesting with high efficiency,because of time and cost.However,farmers are lacking knowledge and information required for selecting suitable combine harvesters and giving the conditions of their rice fields,because both information factors(combine harvester and field condition)impact the field capacity.The field capacity model was generated from combine harvesters with the Thai Hom Mali rice variety(KDML-105).Therefore,this study aimed to determine the prediction model for effective field capacity to combine harvesters when harvesting the Thai Hom Mali rice variety(KDML-105).The methods began by collecting data of 15 combine harvesters,such as field,crop,and machine conditions and operating times;to generate the prediction model for the KDML-105 variety.The prediction model was then validated using 12 combine harvesters that were collected similarly to the model creation.The results showed a root mean square error(RMSE)of 0.24 m^(2)/s for the model.The prediction model can be applied for farmers to select the proper combine harvesters and give their field conditions.