To solve the medium and long term power load forecasting problem,the combination forecasting method is further expanded and a weighted combination forecasting model for power load is put forward.This model is divided ...To solve the medium and long term power load forecasting problem,the combination forecasting method is further expanded and a weighted combination forecasting model for power load is put forward.This model is divided into two stages which are forecasting model selection and weighted combination forecasting.Based on Markov chain conversion and cloud model,the forecasting model selection is implanted and several outstanding models are selected for the combination forecasting.For the weighted combination forecasting,a fuzzy scale joint evaluation method is proposed to determine the weight of selected forecasting model.The percentage error and mean absolute percentage error of weighted combination forecasting result of the power consumption in a certain area of China are 0.7439%and 0.3198%,respectively,while the maximum values of these two indexes of single forecasting models are 5.2278%and 1.9497%.It shows that the forecasting indexes of proposed model are improved significantly compared with the single forecasting models.展开更多
The shrimp beam trawl fishery in the northern South China Sea is characterized by high by-catch and poor selectivity problems.Among by-catch species,banded scad(Caranx(Atule)kalla)is economically the most important on...The shrimp beam trawl fishery in the northern South China Sea is characterized by high by-catch and poor selectivity problems.Among by-catch species,banded scad(Caranx(Atule)kalla)is economically the most important one.The aim of this study is to improve the selective properties of codends for banded scad.Size selectivity of 2 traditional diamond mesh codends,with mesh size 25 and 30 mm(defined as D25 and D30,respectively),and 4 new combined square and diamond mesh codends,with25 mm square-mesh and 25 mm diamond-mesh(S25+D25),30 mm square-mesh and 25 mm diamondmesh(S30+D25),35 mm square-mesh and 25 mm diamond-mesh(S35+D25),and 35 mm square-mesh and18 mm diamond-mesh(S35+D18),were tested for banded scad in shrimp beam trawl fishery of the South China Sea.A total of 54 valid hauls were finished using the covered codend method,and 5750 banded scad were caught.Selective parameters were obtained using the logistic equation with the maximum likelihood method,by incorporating the between-haul variation.The results show that the present minimum mesh size for shrimp beam trawl in the South China Sea,25-mm diamond mesh size,is insufficient to release immature banded scad.The S35+D25 codend is proved to be the most eff ective codend to release immature banded scad,and its 50%retention length(L _(50))is larger than the minimum landing size(MLS=63.5 mm)of banded scad.However,the 95%confidence intervals of L _(50) overlap among the three combined mesh codends,the S25+D25,S30+D25 and S35+D25 codend.For a sustainable exploitation of banded scad,larger mesh sizes are suggested to be investigated for the combined mesh codends.展开更多
Azalomycin F<sub>5a</sub>, a 36-membered macrocyclic lactone isolated from several streptomyces strains, presented remarkable anti-methicillin-resistant Staphylococcus aureus (MRSA) activities. To improve ...Azalomycin F<sub>5a</sub>, a 36-membered macrocyclic lactone isolated from several streptomyces strains, presented remarkable anti-methicillin-resistant Staphylococcus aureus (MRSA) activities. To improve its anti-MRSA potential and to evaluate the probability of MRSA resistant to it before development, the anti-MRSA activities of azalomycin F<sub>5a</sub> in combination with vitamin K<sub>3</sub> were first evaluated using checkerboard assay. Then the minimal concentration inhibiting colony formation by 99% (MIC<sub>99</sub>) and mutant prevention concentration (MPC) of azalomycin F<sub>5a</sub> alone and in combination with vitamin K<sub>3</sub> against MRSA were determined using agar plates with linear antimicrobial concentration decrease. The fractional inhibitory concentration indexes (FICIs) of 0.25 - 0.50 showed the synergistic activity of azalomycin F<sub>5a</sub> in combination with vitamin K<sub>3</sub>. The mutant selection windows (MSWs, MIC<sub>99</sub>-MPC) of azalomycin F<sub>5a</sub> alone against MRSA tested were 2.07 - 6.40 μg/mL, and the MPCs of azalomycin F<sub>5a</sub> in combination with vitamin K<sub>3</sub> against MRSA tested were 1.60 - 3.20 μg/mL. These indicated that the MPCs of azalomycin F<sub>5a</sub> in combination could drop down to below its MIC<sub>99</sub> alone. According to the hypothesis of MSW, the narrower MSWs of azalomycin F<sub>5a </sub>alone, even closed MSWs in combination with vitamin K<sub>3</sub>, together with their synergistic anti-MRSA activities, indicated that azalomycin F<sub>5a </sub>had a good potential to develop as a new antimicrobial agent.展开更多
It's a necessary selection to support the maneuver across Yangtze River by floating bridge constructed by portable steel bridge and civilian ships.It is a comprehensive index for the scheme of bridge raft,containi...It's a necessary selection to support the maneuver across Yangtze River by floating bridge constructed by portable steel bridge and civilian ships.It is a comprehensive index for the scheme of bridge raft,containing a variety of technical factors and uncertainties.The optimization is the selection in the constructing time,quantity of equipments and man power.Based on the calculation result of bridge rafts,an evaluating system is established,consisting of index of spacing between interior bays,raft length,truss numbers,operation difficulty and maximal bending stress.A fuzzy matter element model of optimizing selection of bridge rafts was built up by combining quantitative analysis with qualitative analysis.The method of combination weighting was used to calculate the value of weights index to reduce the subjective randomness.The sequence of schemes and the optimization result were gained finally based on euclid approach degree.The application result shows that it is simple and practical.展开更多
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 ...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展开更多
The two most important activities in maize breeding are the development of inbred lines with high values of general combining ability(GCA)and specific combining ability(SCA),and the identification of hybrids with high...The two most important activities in maize breeding are the development of inbred lines with high values of general combining ability(GCA)and specific combining ability(SCA),and the identification of hybrids with high yield potentials.Genomic selection(GS)is a promising genomic tool to perform selection on the untested breeding material based on the genomic estimated breeding values estimated from the genomic prediction(GP).In this study,GP analyses were carried out to estimate the performance of hybrids,GCA,and SCA for grain yield(GY)in three maize line-by-tester trials,where all the material was phenotyped in 10 to 11 multiple-location trials and genotyped with a mid-density molecular marker platform.Results showed that the prediction abilities for the performance of hybrids ranged from 0.59 to0.81 across all trials in the model including the additive effect of lines and testers.In the model including both additive and non-additive effects,the prediction abilities for the performance of hybrids were improved and ranged from 0.64 to 0.86 across all trials.The prediction abilities of the GCA for GY were low,ranging between-0.14 and 0.13 across all trials in the model including only inbred lines;the prediction abilities of the GCA for GY were improved and ranged from 0.49 to 0.55 across all trials in the model including both inbred lines and testers,while the prediction abilities of the SCA for GY were negative across all trials.The prediction abilities for GY between testers varied from-0.66 to 0.82;the performance of hybrids between testers is difficult to predict.GS offers the opportunity to predict the performance of new hybrids and the GCA of new inbred lines based on the molecular marker information,the total breeding cost could be reduced dramatically by phenotyping fewer multiple-location trials.展开更多
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 ...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.展开更多
Traditional multi-band frequency selective surface (FSS) approaches are hard to achieve a perfect resonance response in a wide band due to the limit of the onset grating lobe frequency determined by the array. To so...Traditional multi-band frequency selective surface (FSS) approaches are hard to achieve a perfect resonance response in a wide band due to the limit of the onset grating lobe frequency determined by the array. To solve this problem, an approach of combining elements in different period to build a hybrid array is presented. The results of series of numerical simulation show that multi-periodicity combined element FSS, which are designed using this approach, usually have much weaker grating lobes than the traditional FSS. Furthermore, their frequency response can be well predicted through the properties of their member element FSS. A prediction method for estimating the degree of expected grating lobe energy loss in designing multi-band FSS using this approach is provided.展开更多
The full-length of intact Zea mays gene for phosphoenolpyruvate carboxylase gene (ZmC4Ppc) is 6 781 bp. The products of PCR for this gene were not clear with poor repeatability, resulting in that it was difficult fo...The full-length of intact Zea mays gene for phosphoenolpyruvate carboxylase gene (ZmC4Ppc) is 6 781 bp. The products of PCR for this gene were not clear with poor repeatability, resulting in that it was difficult for marker-assisted selection (MAS) both in rice and maize. For selecting the markers for MAS, sequences presented only in maize rather than in rice were identified by BLAST, and used for primer design using Primer Premier 5.0. A pair of specific primer termed MRpc (Forward: 5' AAGCAGGGAAGCGAGACG 3', Reverse: 5' GATTGCCGCCAGCAGTAG 3') was used for selection of transformed rice, and ZmC4Ppc could be highly and constitutively expressed at each tested developmental stages in the transformed rice selected by using MRpc. Thus, MRpc was used for MAS of progenies carrying ZmC4Ppc gene in rice and some restorer lines with ZmC4Ppc (e.g. FPM881) derived from ZmC4Ppc-transformed Kitaake backcrossed with a restorer line Shuhui 881 were obtained. The analyses on genetic background, PEPCase activity, net photosynthetic rate, general combining ability (GCA) and specific combining ability (SCA) of FPM881 showed that similarity of genetic background reached above 95%, the PEPCase and net photosynthetic rate were higher than those of the control, and some of the progenies carrying ZmC4Ppc gene had better GCA and SCA for grain yield per plant, number of panicles per plant, and 1000-grain weight than those of the control. This suggested that the introduction of maize ZmC4Ppc gene via MAS and its stable expression could increase grain yield of rice and would likely provide a pathway for rice varietal improvement.展开更多
Cooperative communication is going to play a vital role in the next generation wireless networks. In this paper we derive the expression for symbol error probability (SEP) of a two-user cooperative diversity system, w...Cooperative communication is going to play a vital role in the next generation wireless networks. In this paper we derive the expression for symbol error probability (SEP) of a two-user cooperative diversity system, where two users cooperate through the decode-and-forward (DF) relaying with binary phase-shift keying (BPSK) modulation in a flat Rayleigh fading environment. We compare the computational results obtained by the SEP expression with the simulation results using maximal-ratio combining (MRC), equal-gain combining (EGC) and selection combining (SC) techniques. Numerical results show the performance of a cooperative diversity system with maximal-ratio combining is giving better results compared to SC and EGC techniques.展开更多
According to the typical engineering samples, a neural net work model with genetic algorithm to optimize weight values is put forward to forecast the productivities and efficiencies of mining faces. By this model we c...According to the typical engineering samples, a neural net work model with genetic algorithm to optimize weight values is put forward to forecast the productivities and efficiencies of mining faces. By this model we can obtain the possible achievements of available equipment combinations under certain geological situations of fully-mechanized coal mining faces. Then theory of fuzzy selection is applied to evaluate the performance of each equipment combination. By detailed empirical analysis, this model integrates the functions of forecasting mining faces' achievements and selecting optimal equipment combination and is helpful to the decision of equipment combination for fully-mechanized coal mining.展开更多
In this paper, we consider a spectrum sharing scheme that is a joint optimization of relay selection and power allocation at the secondary transmitter, which aims to achieve the maximum possible throughput for the sec...In this paper, we consider a spectrum sharing scheme that is a joint optimization of relay selection and power allocation at the secondary transmitter, which aims to achieve the maximum possible throughput for the secondary user. This paper considers the scenario where the primary user is incapable of supporting its target signal-to-noise ratio (SNR). More especially, the secondary transmitter tries to assist the primary user with achieving its target SNR by cooperative amplify-and-forward (AF) relaying with two-phase. By exhaustive search for all candidate secondary transmitters, an optimal secondary transmitter can be selected, which not only can satisfy the primary user’s target SNR, but also maximize the secondary user’s throughput. The optimal secondary transmitter acts as a relay for the primary user by allocating a part of its power to amplify-and-forward the primary signal over the primary user’s licensed spectrum bands. At the same time, as a reward, the optimal secondary transmitter uses the remaining power to transmit its own signal over the remaining licensed spectrum bands. Thus, the secondary user obtains the spectrum access opportunities. Besides, there is no interference between the primary user and the secondary user. We study the joint optimization of relay selection and power allocation such that the secondary user’s throughput is maximized on the condition that it satisfies the primary user’s target SNR. From the simulation, it is shown that the joint optimization of relay selection and power allocation provides a significant throughput gain compared with random relay selection with optimal power allocation (OPA) and random relay selection with water-filling power allocation (WPA). Moreover, the simulation results also shown that our spectrum sharing scheme obtains the win-win solution for the primary system and the secondary system.展开更多
In this paper bit error rate (BER) performance is analyzed for multiple input-multiple output (MIMO) communications systems using antenna selection in the transmitter, maximal ratio combining (MRC) and linear de-corre...In this paper bit error rate (BER) performance is analyzed for multiple input-multiple output (MIMO) communications systems using antenna selection in the transmitter, maximal ratio combining (MRC) and linear de-correlating detector (LDD) in the receiver in wide band code division multiple access (WCDMA) downlink channels with correlated Nakagami fading. The MRC maximizes signal to noise ratio of the received signal, then the LDD cancels out multiple access interference (MAI). Theoretical results are validated using computer simulations. Moreover, a pilot based estimation method is proposed to jointly estimate the channel gains and the rows of the LDD operator. Simulation results show that using this proposed method, diversity order is maintained in the receiver. Furthermore, our analysis shows the spectral efficiency degradation due to the pilot based strategy is negligible.展开更多
文摘To solve the medium and long term power load forecasting problem,the combination forecasting method is further expanded and a weighted combination forecasting model for power load is put forward.This model is divided into two stages which are forecasting model selection and weighted combination forecasting.Based on Markov chain conversion and cloud model,the forecasting model selection is implanted and several outstanding models are selected for the combination forecasting.For the weighted combination forecasting,a fuzzy scale joint evaluation method is proposed to determine the weight of selected forecasting model.The percentage error and mean absolute percentage error of weighted combination forecasting result of the power consumption in a certain area of China are 0.7439%and 0.3198%,respectively,while the maximum values of these two indexes of single forecasting models are 5.2278%and 1.9497%.It shows that the forecasting indexes of proposed model are improved significantly compared with the single forecasting models.
基金Supported by the Special Fund for Agro-scientific Research in the Public Interest(No.201203018)
文摘The shrimp beam trawl fishery in the northern South China Sea is characterized by high by-catch and poor selectivity problems.Among by-catch species,banded scad(Caranx(Atule)kalla)is economically the most important one.The aim of this study is to improve the selective properties of codends for banded scad.Size selectivity of 2 traditional diamond mesh codends,with mesh size 25 and 30 mm(defined as D25 and D30,respectively),and 4 new combined square and diamond mesh codends,with25 mm square-mesh and 25 mm diamond-mesh(S25+D25),30 mm square-mesh and 25 mm diamondmesh(S30+D25),35 mm square-mesh and 25 mm diamond-mesh(S35+D25),and 35 mm square-mesh and18 mm diamond-mesh(S35+D18),were tested for banded scad in shrimp beam trawl fishery of the South China Sea.A total of 54 valid hauls were finished using the covered codend method,and 5750 banded scad were caught.Selective parameters were obtained using the logistic equation with the maximum likelihood method,by incorporating the between-haul variation.The results show that the present minimum mesh size for shrimp beam trawl in the South China Sea,25-mm diamond mesh size,is insufficient to release immature banded scad.The S35+D25 codend is proved to be the most eff ective codend to release immature banded scad,and its 50%retention length(L _(50))is larger than the minimum landing size(MLS=63.5 mm)of banded scad.However,the 95%confidence intervals of L _(50) overlap among the three combined mesh codends,the S25+D25,S30+D25 and S35+D25 codend.For a sustainable exploitation of banded scad,larger mesh sizes are suggested to be investigated for the combined mesh codends.
文摘Azalomycin F<sub>5a</sub>, a 36-membered macrocyclic lactone isolated from several streptomyces strains, presented remarkable anti-methicillin-resistant Staphylococcus aureus (MRSA) activities. To improve its anti-MRSA potential and to evaluate the probability of MRSA resistant to it before development, the anti-MRSA activities of azalomycin F<sub>5a</sub> in combination with vitamin K<sub>3</sub> were first evaluated using checkerboard assay. Then the minimal concentration inhibiting colony formation by 99% (MIC<sub>99</sub>) and mutant prevention concentration (MPC) of azalomycin F<sub>5a</sub> alone and in combination with vitamin K<sub>3</sub> against MRSA were determined using agar plates with linear antimicrobial concentration decrease. The fractional inhibitory concentration indexes (FICIs) of 0.25 - 0.50 showed the synergistic activity of azalomycin F<sub>5a</sub> in combination with vitamin K<sub>3</sub>. The mutant selection windows (MSWs, MIC<sub>99</sub>-MPC) of azalomycin F<sub>5a</sub> alone against MRSA tested were 2.07 - 6.40 μg/mL, and the MPCs of azalomycin F<sub>5a</sub> in combination with vitamin K<sub>3</sub> against MRSA tested were 1.60 - 3.20 μg/mL. These indicated that the MPCs of azalomycin F<sub>5a</sub> in combination could drop down to below its MIC<sub>99</sub> alone. According to the hypothesis of MSW, the narrower MSWs of azalomycin F<sub>5a </sub>alone, even closed MSWs in combination with vitamin K<sub>3</sub>, together with their synergistic anti-MRSA activities, indicated that azalomycin F<sub>5a </sub>had a good potential to develop as a new antimicrobial agent.
文摘It's a necessary selection to support the maneuver across Yangtze River by floating bridge constructed by portable steel bridge and civilian ships.It is a comprehensive index for the scheme of bridge raft,containing a variety of technical factors and uncertainties.The optimization is the selection in the constructing time,quantity of equipments and man power.Based on the calculation result of bridge rafts,an evaluating system is established,consisting of index of spacing between interior bays,raft length,truss numbers,operation difficulty and maximal bending stress.A fuzzy matter element model of optimizing selection of bridge rafts was built up by combining quantitative analysis with qualitative analysis.The method of combination weighting was used to calculate the value of weights index to reduce the subjective randomness.The sequence of schemes and the optimization result were gained finally based on euclid approach degree.The application result shows that it is simple and practical.
文摘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
基金financial support of the Shanghai Agriculture Applied Technology Development Program of China(Z20190101)the Harvest Plus Project+7 种基金the Genomic Opensource Breeding Informatics Initiative(GOBII)(OPP1093167)supported by the Bill&Melinda Gates Foundationthe CGIAR Research Program(CRP)on MAIZEW1&W2 support from the Governments of Australia,Belgium,Canada,China,France,India,Japan,Republic of Korea,Mexico,the Netherlands,New Zealand,Norway,Sweden,Switzerland,the United Kingdom,the United States,and the World Bankgrants from the National Key Research and Development Program of China(2016YFD0101803)the National Natural Science Foundation of China(31801442)Shenyang City Key Laboratory of Maize Genomic Selection,Liaoning Province Key Scientific and Technological Research and Development Project(2011208001)the CIMMYT-China Specialty Maize Research Center Project funded by the Shanghai Municipal Finance Bureau(KF201802)the Chinese Scholarship Council。
文摘The two most important activities in maize breeding are the development of inbred lines with high values of general combining ability(GCA)and specific combining ability(SCA),and the identification of hybrids with high yield potentials.Genomic selection(GS)is a promising genomic tool to perform selection on the untested breeding material based on the genomic estimated breeding values estimated from the genomic prediction(GP).In this study,GP analyses were carried out to estimate the performance of hybrids,GCA,and SCA for grain yield(GY)in three maize line-by-tester trials,where all the material was phenotyped in 10 to 11 multiple-location trials and genotyped with a mid-density molecular marker platform.Results showed that the prediction abilities for the performance of hybrids ranged from 0.59 to0.81 across all trials in the model including the additive effect of lines and testers.In the model including both additive and non-additive effects,the prediction abilities for the performance of hybrids were improved and ranged from 0.64 to 0.86 across all trials.The prediction abilities of the GCA for GY were low,ranging between-0.14 and 0.13 across all trials in the model including only inbred lines;the prediction abilities of the GCA for GY were improved and ranged from 0.49 to 0.55 across all trials in the model including both inbred lines and testers,while the prediction abilities of the SCA for GY were negative across all trials.The prediction abilities for GY between testers varied from-0.66 to 0.82;the performance of hybrids between testers is difficult to predict.GS offers the opportunity to predict the performance of new hybrids and the GCA of new inbred lines based on the molecular marker information,the total breeding cost could be reduced dramatically by phenotyping fewer multiple-location trials.
文摘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.
基金supported by the National Natural Science Foundation of China(90305026).
文摘Traditional multi-band frequency selective surface (FSS) approaches are hard to achieve a perfect resonance response in a wide band due to the limit of the onset grating lobe frequency determined by the array. To solve this problem, an approach of combining elements in different period to build a hybrid array is presented. The results of series of numerical simulation show that multi-periodicity combined element FSS, which are designed using this approach, usually have much weaker grating lobes than the traditional FSS. Furthermore, their frequency response can be well predicted through the properties of their member element FSS. A prediction method for estimating the degree of expected grating lobe energy loss in designing multi-band FSS using this approach is provided.
文摘The full-length of intact Zea mays gene for phosphoenolpyruvate carboxylase gene (ZmC4Ppc) is 6 781 bp. The products of PCR for this gene were not clear with poor repeatability, resulting in that it was difficult for marker-assisted selection (MAS) both in rice and maize. For selecting the markers for MAS, sequences presented only in maize rather than in rice were identified by BLAST, and used for primer design using Primer Premier 5.0. A pair of specific primer termed MRpc (Forward: 5' AAGCAGGGAAGCGAGACG 3', Reverse: 5' GATTGCCGCCAGCAGTAG 3') was used for selection of transformed rice, and ZmC4Ppc could be highly and constitutively expressed at each tested developmental stages in the transformed rice selected by using MRpc. Thus, MRpc was used for MAS of progenies carrying ZmC4Ppc gene in rice and some restorer lines with ZmC4Ppc (e.g. FPM881) derived from ZmC4Ppc-transformed Kitaake backcrossed with a restorer line Shuhui 881 were obtained. The analyses on genetic background, PEPCase activity, net photosynthetic rate, general combining ability (GCA) and specific combining ability (SCA) of FPM881 showed that similarity of genetic background reached above 95%, the PEPCase and net photosynthetic rate were higher than those of the control, and some of the progenies carrying ZmC4Ppc gene had better GCA and SCA for grain yield per plant, number of panicles per plant, and 1000-grain weight than those of the control. This suggested that the introduction of maize ZmC4Ppc gene via MAS and its stable expression could increase grain yield of rice and would likely provide a pathway for rice varietal improvement.
文摘Cooperative communication is going to play a vital role in the next generation wireless networks. In this paper we derive the expression for symbol error probability (SEP) of a two-user cooperative diversity system, where two users cooperate through the decode-and-forward (DF) relaying with binary phase-shift keying (BPSK) modulation in a flat Rayleigh fading environment. We compare the computational results obtained by the SEP expression with the simulation results using maximal-ratio combining (MRC), equal-gain combining (EGC) and selection combining (SC) techniques. Numerical results show the performance of a cooperative diversity system with maximal-ratio combining is giving better results compared to SC and EGC techniques.
文摘According to the typical engineering samples, a neural net work model with genetic algorithm to optimize weight values is put forward to forecast the productivities and efficiencies of mining faces. By this model we can obtain the possible achievements of available equipment combinations under certain geological situations of fully-mechanized coal mining faces. Then theory of fuzzy selection is applied to evaluate the performance of each equipment combination. By detailed empirical analysis, this model integrates the functions of forecasting mining faces' achievements and selecting optimal equipment combination and is helpful to the decision of equipment combination for fully-mechanized coal mining.
文摘In this paper, we consider a spectrum sharing scheme that is a joint optimization of relay selection and power allocation at the secondary transmitter, which aims to achieve the maximum possible throughput for the secondary user. This paper considers the scenario where the primary user is incapable of supporting its target signal-to-noise ratio (SNR). More especially, the secondary transmitter tries to assist the primary user with achieving its target SNR by cooperative amplify-and-forward (AF) relaying with two-phase. By exhaustive search for all candidate secondary transmitters, an optimal secondary transmitter can be selected, which not only can satisfy the primary user’s target SNR, but also maximize the secondary user’s throughput. The optimal secondary transmitter acts as a relay for the primary user by allocating a part of its power to amplify-and-forward the primary signal over the primary user’s licensed spectrum bands. At the same time, as a reward, the optimal secondary transmitter uses the remaining power to transmit its own signal over the remaining licensed spectrum bands. Thus, the secondary user obtains the spectrum access opportunities. Besides, there is no interference between the primary user and the secondary user. We study the joint optimization of relay selection and power allocation such that the secondary user’s throughput is maximized on the condition that it satisfies the primary user’s target SNR. From the simulation, it is shown that the joint optimization of relay selection and power allocation provides a significant throughput gain compared with random relay selection with optimal power allocation (OPA) and random relay selection with water-filling power allocation (WPA). Moreover, the simulation results also shown that our spectrum sharing scheme obtains the win-win solution for the primary system and the secondary system.
文摘In this paper bit error rate (BER) performance is analyzed for multiple input-multiple output (MIMO) communications systems using antenna selection in the transmitter, maximal ratio combining (MRC) and linear de-correlating detector (LDD) in the receiver in wide band code division multiple access (WCDMA) downlink channels with correlated Nakagami fading. The MRC maximizes signal to noise ratio of the received signal, then the LDD cancels out multiple access interference (MAI). Theoretical results are validated using computer simulations. Moreover, a pilot based estimation method is proposed to jointly estimate the channel gains and the rows of the LDD operator. Simulation results show that using this proposed method, diversity order is maintained in the receiver. Furthermore, our analysis shows the spectral efficiency degradation due to the pilot based strategy is negligible.