This paper reports"the fourth set"of drilling tillage after"ploughing(hoeing)"by manpower,animal power and tractor——Fenlong tillage technology(referred to as"Fenlong technology").It mak...This paper reports"the fourth set"of drilling tillage after"ploughing(hoeing)"by manpower,animal power and tractor——Fenlong tillage technology(referred to as"Fenlong technology").It makes the cultivated land and saline alkali land transformed into"sponge"farmland through"drill bit"vertically digging into the soil,one-time deep cultivation,not disturbing soil layer,and granulating the soil,to bring about the effects of"expanding the land,releasing the natural force,water conservation,disaster reduction,carbon reduction,tillage saving,fertilizer saving and grain increasing",and can broaden the space for human survival and development.It has been applied to more than 50 crops in 28 provinces,including Guangxi,Hebei and Tibet.Without increasing the use of fertilizer and water,the yield of varieties in cultivated land increased by 10%-50%,while that in saline and alkaline land increased by 20%-100%.The storage of natural precipitation increased by 100%,and drought,high temperature and low temperature decreased by 20%-30%,and carbon sequestration and emission reduction reached 20%.It is proposed that China can implement the"dual strategy"platform of farmland,saline alkali land,rivers and water bodies constructing the"incremental""five new warehouses"of grain,water,fish,sugar,etc.and"increased grain return"abroad,to ensure national security.展开更多
In this paper,we optimize the spectrum efficiency(SE)of uplink massive multiple-input multiple-output(MIMO)system with imperfect channel state information(CSI)over Rayleigh fading channel.The SE optimization problem i...In this paper,we optimize the spectrum efficiency(SE)of uplink massive multiple-input multiple-output(MIMO)system with imperfect channel state information(CSI)over Rayleigh fading channel.The SE optimization problem is formulated under the constraints of maximum power and minimum rate of each user.Then,we develop a near-optimal power allocation(PA)scheme by using the successive convex approximation(SCA)method,Lagrange multiplier method,and block coordinate descent(BCD)method,and it can obtain almost the same SE as the benchmark scheme with lower complexity.Since this scheme needs three-layer iteration,a suboptimal PA scheme is developed to further reduce the complexity,where the characteristic of massive MIMO(i.e.,numerous receive antennas)is utilized for convex reformulation,and the rate constraint is converted to linear constraints.This suboptimal scheme only needs single-layer iteration,thus has lower complexity than the near-optimal scheme.Finally,we joint design the pilot power and data power to further improve the performance,and propose an two-stage algorithm to obtain joint PA.Simulation results verify the effectiveness of the proposed schemes,and superior SE performance is achieved.展开更多
To meet the communication services with diverse requirements,dynamic resource allocation has shown increasing importance.In this paper,we consider the multi-slot and multi-user resource allocation(MSMU-RA)in a downlin...To meet the communication services with diverse requirements,dynamic resource allocation has shown increasing importance.In this paper,we consider the multi-slot and multi-user resource allocation(MSMU-RA)in a downlink cellular scenario with the aim of maximizing system spectral efficiency while guaranteeing user fairness.We first model the MSMURA problem as a dual-sequence decision-making process,and then solve it by a novel Transformerbased deep reinforcement learning(TDRL)approach.Specifically,the proposed TDRL approach can be achieved based on two aspects:1)To adapt to the dynamic wireless environment,the proximal policy optimization(PPO)algorithm is used to optimize the multi-slot RA strategy.2)To avoid co-channel interference,the Transformer-based PPO algorithm is presented to obtain the optimal multi-user RA scheme by exploring the mapping between user sequence and resource sequence.Experimental results show that:i)the proposed approach outperforms both the traditional and DRL methods in spectral efficiency and user fairness,ii)the proposed algorithm is superior to DRL approaches in terms of convergence speed and generalization performance.展开更多
Dynamic resource allocation(DRA) is a key technology to improve system performances in GEO multi-beam satellite systems. And, since the cache resource on the satellite is very valuable and limited, DRA problem under r...Dynamic resource allocation(DRA) is a key technology to improve system performances in GEO multi-beam satellite systems. And, since the cache resource on the satellite is very valuable and limited, DRA problem under restricted cache resources is also an important issue to be studied. This paper mainly investigates the DRA problem of carrier resources under certain cache constraints. What's more, with the aim to satisfy all users' traffic demands as more as possible, and to maximize the utilization of the bandwidth, we formulate a multi-objective optimization problem(MOP) where the satisfaction index and the spectrum efficiency are jointly optimized. A modified strategy SA-NSGAII which combines simulated annealing(SA) and non-dominated sorted genetic algorithm-II(NSGAII) is proposed to approximate the Pareto solution to this MOP problem. Simulation results show the effectiveness of the proposed algorithm in terms of satisfaction index, spectrum efficiency, occupied cache, and etc.展开更多
Space time coding can provide high data rate and performance gain for wireless communication system. Performance comparison of space time trellis codes and space time transmit diversity is carried out under the sam...Space time coding can provide high data rate and performance gain for wireless communication system. Performance comparison of space time trellis codes and space time transmit diversity is carried out under the same bandwidth efficiency in this paper. We also propose some optimum low rate space time trellis codes in quasi static Rayleigh fading chan ̄nel. Performance analysis and simulation show that the low rate space time trellis codes outperform space time transmit diversity at the same bandwidth efficiency, and are more suitable for the power limited wireless communication system which has no strict requirement on bandwidth efficiency.展开更多
This paper investigates the achievable uplink spectral efficiency(SE) of a massive multi-input multi-output(MIMO) system with a mixed analog-to-digital converter(ADC) receiver architecture, in which some antennas are ...This paper investigates the achievable uplink spectral efficiency(SE) of a massive multi-input multi-output(MIMO) system with a mixed analog-to-digital converter(ADC) receiver architecture, in which some antennas are equipped with full-resolution ADCs while others are deployed with low-resolution ADCs. We derive the theoretical results and corresponding approximate expressions of the achievable SE in multi-cell systems with maximum ratio combining(MRC) detector and in single-cell systems with zero-forcing(ZF) detector. Based on approximated results, the effects of physical parameters, including the transmit power, the number of antennas, the proportion of full-resolution ADCs and the quantization precision of the low-resolution ADCs on the achievable SE are revealed. Furthermore, we propose the power allocation algorithms based on the lower bound and upper bound of approximate achievable SE. Our results show that the total achievable SE improves by increasing the number of BS antennas, the signal-to-noise ratio(SNR), and the quantization precision. Results showcase that proposed power allocation algorithms remarkably improve the total achievable SE comparing to the equal power allocation algorithm, which verifies the effectiveness of our proposed schemes.展开更多
The incompatibility of China's economy and finance has to some extent inhibited the development of rural economy. Taking Hubei Province for example,we measure the allocation efficiency of rural financial resources...The incompatibility of China's economy and finance has to some extent inhibited the development of rural economy. Taking Hubei Province for example,we measure the allocation efficiency of rural financial resources from the perspective of agricultural input and output,and use the modern rural financial development theory to set forth some policy recommendations on how to build a new rural financial resource allocation system. Studies have shown that the allocation efficiency of rural financial resources is low in China,and improving the allocation efficiency of rural financial resources is the key to perfecting rural financial environment while increasing financial support for agriculture.展开更多
Metamorphic In0.55Ga0.45P/In0.06Ga0.94As/Ge triple-junction (3J-MM) solar cells are grown on Ge (100) sub- strates via metal organic chemical vapor deposition. Epi-structural analyses such as high resolution x-ray...Metamorphic In0.55Ga0.45P/In0.06Ga0.94As/Ge triple-junction (3J-MM) solar cells are grown on Ge (100) sub- strates via metal organic chemical vapor deposition. Epi-structural analyses such as high resolution x-ray diffrac- tion, photoluminence, cathodoluminescence and HRTEM are employed and the results show that the high crystal quality of 3J-MM solar cells is obtained with low threading dislocation density of graded buffer (an average value of 6.8× 10^4/cm2). Benefitting from the optimized bandgap combination, under one sun, AM0 spectrum, 25℃ conditions, the conversion efficiency is achieved about 32%, 5% higher compared with the lattice-matched In0.49Ga0.51P/In0.01Ga0.99As/Ge triple junction (3J-LM) solar cell. Under 1-MeV electron irradiation test, the degradation of the EQE and I-V characteristics of 3J-MM solar cells is at the same level as the 33-LM solar cell. The end-of-life efficiency is -27.1%. Therefore, the metamorphic triple-junction solar cell may be a promising candidate for next-generation space multi-junction solar cells.展开更多
Based on grey neural network and particle swarm optimization algorithm,an automated stereo garage decision model is proposed to solve the problems of long waiting queue and low efficiency of automated parking garage.T...Based on grey neural network and particle swarm optimization algorithm,an automated stereo garage decision model is proposed to solve the problems of long waiting queue and low efficiency of automated parking garage.The gray neural network is used to forecast the stay time of the vehicle and particle swarm optimization algorithm is used to allocate the parking spaces in the stereo garage.The proposed stereo garage mathematical model is established on condition that vehicle arrival interval obeys Poisson distribution.The performance of stereo garage is evaluated by the average waiting time,average waiting queue length,average service time and average energy consumption of the customers.By comparing the efficiency indexes of the existing model based on near-distribution principle and the proposed model based on gray neural network and particle swarm algorithm,it is proved that the proposed model based on gray neural network and particle swarm algorithm is effective in improving the efficiency of garage operation and reducing the energy consumption of garage.展开更多
An efficient spaee-time-frequency (STF) coding strategy for multi-input multi-output orthogonal frequency division multiplexing (MIMO-OFDM) systems is presented for high bit rate data transmission over frequency s...An efficient spaee-time-frequency (STF) coding strategy for multi-input multi-output orthogonal frequency division multiplexing (MIMO-OFDM) systems is presented for high bit rate data transmission over frequency selective fading channels. The proposed scheme is a new approach to space-time-frequency coded OFDM (ODFDM) that combines OFDM with space-time coding, linear precoding and adaptive power allocation to provide higher quality of transmission in terms of the bit error rate performance and power efficiency. In addition to exploiting the maximux diversity gain in frequency, time and space, the proposed scheme enjoys high coding advantages and low-complexity decoding. The significant performance improvement of our design is confirned by corroborating numerical simulations.展开更多
Biomass allocation and assimilation efficiency of natural Amour linden (Tilia amurensis) samplings in different light regimes were analyzed in the paper. The results showed that shoot increment of samplings in gap was...Biomass allocation and assimilation efficiency of natural Amour linden (Tilia amurensis) samplings in different light regimes were analyzed in the paper. The results showed that shoot increment of samplings in gap was the highest and that of samplings under canopy was the least. Samplings in gap expressed apical dominance strongly but samplings in full sun and under canopy behaved intensive branching. Lateral competition or moderate shading was favored to bole construction. The patters of biomass allocation of samplings in different light environment were rather similar. The biomass translocated to stem was more than that to other organs, and about one half of photosynthate was used to support leaf turn over. On the contrary, photosynthates of samplings in full sun were mostly consumed in leaves bearing and energy balancing. The carbon assimilation for leaves of samplings in gap was the most efficient, and more carbons were fixed and translocated to non-photosynthetic organs, especially to stemwood.展开更多
A cross-layer design(CLD)scheme with combination of power allocation,adaptive modulation(AM)and automatic repeat request(ARQ)is presented for space-time coded MIMO system under imperfect feedback,and the corresponding...A cross-layer design(CLD)scheme with combination of power allocation,adaptive modulation(AM)and automatic repeat request(ARQ)is presented for space-time coded MIMO system under imperfect feedback,and the corresponding system performance is investigated in a Rayleigh fading channel.Based on imperfect feedback information,a suboptimal power allocation(PA)scheme is derived to maximize the average spectral efficiency(SE)of the system.The scheme is based on a so-called compressed SNR criterion,and has a closed-form expression for positive power allocation,thus being computationally efficient.Moreover,it can improve SE of the presented CLD.Besides,due to better approximation,it obtains the performance close to the existing optimal approach which requires numerical search.Simulation results show that the proposed CLD with PA can achieve higher SE than the conventional CLD with equal power allocation scheme,and has almost the same performance as CLD with optimal PA.However,it has lower calculation complexity.展开更多
The problem of the simultaneous multi-user resource allocation algorithm in orthogonal frequency division multiple access(OFDMA)based systems has recently attracted significant interest.However,most studies focus on m...The problem of the simultaneous multi-user resource allocation algorithm in orthogonal frequency division multiple access(OFDMA)based systems has recently attracted significant interest.However,most studies focus on maximizing the system throughput and spectral efficiency.As the green radio is essential in 5G and future networks,the energy efficiency becomes the major concern.In this paper,we develop four resource allocation schemes in the downlink OFDMA network and the main focus is on analyzing the energy efficiency of these schemes.Specifically,we employ the advanced multi-antenna technology in a multiple input-multiple output(MIMO)system.The first scheme is based on transmit spatial diversity(TSD),in which the vector channel with the highest gain between the base station(BTS)and specific antenna at the remote terminal(RT)is chosen for transmission.The second scheme further employs spatial multiplexing on the MIMO system to enhance the throughput.The space-division multiple-access(SDMA)scheme assigns single subcarrier simultaneously to RTs with pairwise“nearly orthogonal”spatial signatures.In the fourth scheme,we propose to design the transmit beamformers based on the zero-forcing(ZF)criterion such that the multi-user interference(MUI)is completely removed.We analyze the tradeoff between the throughput and power consumption and compare the performance of these schemes in terms of the energy efficiency.展开更多
5G has pushed the use of radio spectrum to a new level,and cognitive clustering network can effectively improve the utilization of radio spectrum,which is a feasible way to solve the growing demand for wireless commun...5G has pushed the use of radio spectrum to a new level,and cognitive clustering network can effectively improve the utilization of radio spectrum,which is a feasible way to solve the growing demand for wireless communications.However,cognitive clustering network is vulnerable to PUEA attack,which will lead to the degradation of system detection performance,thereby reducing the energy efficiency.Aiming at these problems,this paper investigates the optimal energy efficiency resource allocation scheme for cognitive clustering network under PUEA attack.A cooperative user selection algorithm based on selection factor is proposed to effectively resist PUEA user attack and improve detection performance.We construct the energy efficiency optimization problem under multi-constraint conditions and transform the nonlinear programming problem into parametric programming problem,which is solved by Lagrangian function and Karush-Kuhn-Tucker condition.Then the sub-gradient iterative algorithm based on optimal energy efficiency under PUEA attack is proposed and its complexity is analyzed.Simulation results indicate that proposed method is effective when subjected to PUEA attacks,and the impact of different parameters on energy efficiency is analyzed.展开更多
Unlike most of the existing methods in Space Time coding (STC) system which focus on design of STC gaining full rate and/or maximum diversity, we propose an approach to improve spectral efficiency of the code. The pro...Unlike most of the existing methods in Space Time coding (STC) system which focus on design of STC gaining full rate and/or maximum diversity, we propose an approach to improve spectral efficiency of the code. The proposed scheme carries more information symbols in each transmission block as compare to its counterpart code, and yet retains the property of simple decoding. Simulation results show that transmit diversity is retained with improvement of code efficiency. We mainly focus on Four transmit antenna scheme but it can be generalized for any number of transmit antennas.展开更多
Invasion is often facilitated by high resources availabilities and suppressed under low resources habitats. However, a number of invasive plants can successfully establish and dominate in resource-poor and (or) the ...Invasion is often facilitated by high resources availabilities and suppressed under low resources habitats. However, a number of invasive plants can successfully establish and dominate in resource-poor and (or) the understory of closed forests, indicating the plant's performances are habitats-dependent and species-specific. It is therefore necessary to explore the ecophysiological characteristics associated invasiveness for one invasive species across multiple resources availabilities whilst taking the relatedness into these comparative studies. In this study, invasive Eupitorium adenophorum and its native congener E. japonicum grew under different resource gradients in terms of light levels and soil nitrogen additions to identify the functional significance morphological and physiological traits associated closely with invasion and to examine their comparative responses. Photosynthetic carbon gain, biomass allocation and resource-use efficiency are evaluated in this pot experiment. Across treatments, E. adenophorum exhibited consistently higher values for most of the morphological variables including plant stature, relative growth rate (RGR), leaf root ratio (LRR), leaf area ratio (LAR), total leaf area, and lower root: shoot ratio (RSR). Significantly higher Pmax corresponded with higher photosynthetic nitrogen use efficiency (PNUE) and photosynthetic energy use efficiency (PEUE) especially in low light and (or) unfertile condition. Higher Gs and Pmax but lower photosynthetic water use efficiency (WUE) indicated the trade-off relationship between WUE and PNUE for E. adenophorum. Final biomasses were higher for E. adenophorum in nutrient and(or) light limited conditions, in which higher leaf construction cost(CC) compared with E. japonicum could be over-compensated by its significantly higher assimilation rates. The effects of light levels on these plant attributes were stronger than soil nutrient contents. The responses of these two congeneric species to light and nitrogen availabilities were similar, but the differences were magnified in resources limited conditions, indicating the better performancer at acquiring and at using limited resources of E. adenophorum over its co-occurring native flora. Our study presented the distinctive advantages of E. adenophorum in resources-poor environments, indicating conventional strategy of managing resources levels to control the invasion and expending of exotic species may not be as effective as expected.展开更多
Based on the existing literature,this paper analyzed and explored the factors that affect the efficiency of resource allocation,and evaluated the current situation of resource allocation in various fields.It is found ...Based on the existing literature,this paper analyzed and explored the factors that affect the efficiency of resource allocation,and evaluated the current situation of resource allocation in various fields.It is found that with the emergence of the new pattern of China’s economic development,the economic growth rate has slowed down,and the method of large-scale production driving economic growth is no longer applicable to the current economic situation.Nowadays,when structural transformation and upgrading have entered a new stage,to achieve the optimization of resource allocation efficiency,it is necessary to start from three aspects:improving information transparency,upgrading industrial structure,and planning government intervention.Through the adaptation analysis of blockchain technology and the existing problems in optimizing resource allocation efficiency,it explored the feasibility of blockchain technology to optimize resource allocation efficiency,and promote economical,efficient and high-quality development.展开更多
With the rapid development of Internet technology,the importance of blockchain technology has become increasingly prominent.Faced with this situation,extensive research has been carried out at home and abroad.Through ...With the rapid development of Internet technology,the importance of blockchain technology has become increasingly prominent.Faced with this situation,extensive research has been carried out at home and abroad.Through the analysis of relevant literature on blockchain in recent years,it is found that there are many research results of blockchain technology in medical care,finance,education,etc.,but its application in the field of resource allocation efficiency is rare.From the existing studies on the influencing factors of resource allocation efficiency in China,it is found that there are significant differences in resource allocation efficiency between China and some developed countries or between various provinces and cities of China.展开更多
This article,which is based on panel data of Chinese state-owned industrial enterprises over the period 2006-2011,analyzes Labor reallocation Efficiency of State-Owned Enterprises with Syrquin's analysis of the total...This article,which is based on panel data of Chinese state-owned industrial enterprises over the period 2006-2011,analyzes Labor reallocation Efficiency of State-Owned Enterprises with Syrquin's analysis of the total Reallocation effect of Resources. The results show that:①Labor allocation efficiency keeps a high level all the time;②The contribution that labor Reallocation efficiency makes to the growth of labor productivity has been at a low rate. Therefore, our government had better deepen the reform of state-owned enterprises and the evolvement of marketization展开更多
Cognitive Radio(CR) is a promising technique for the next generation mobile communi-cation system for its capability to solve the conflicts between the scarcity and underutilization of spectrum.In this paper,aiming at...Cognitive Radio(CR) is a promising technique for the next generation mobile communi-cation system for its capability to solve the conflicts between the scarcity and underutilization of spectrum.In this paper,aiming at maximizing the system capacity of a multi-antenna CR system on the premise that avoid interference to the primary system in the same band simultaneously,a resource allocation method which is able to avoid interference between PRimary(PR) and CR users by pro-jecting the transmit signals of CR users on the null space of the PR users' channels is proposed.CR users with better channel condition are selected,and the interference from CR system to PR users can be removed completely by projecting the transmit signals of CR system on the null-space of PR users' channels.Parallel sub-channels are constructed for CR users through Singular Value Decomposition(SVD).At last,waterfilling is also adopted to increase the CR users' capacity.Simulation result demonstrates that compared with existing methods,our method can improve the achievable sum rate of CR users as well as reduce the outage probability of PR users.展开更多
基金Supported by the Guangxi Innovation Driven Development Project(GUIKE AA20302020)Basic Scientific Research Business of Guangxi Academy of Agricultural Sciences(GUINONGKE 2021YT056)。
文摘This paper reports"the fourth set"of drilling tillage after"ploughing(hoeing)"by manpower,animal power and tractor——Fenlong tillage technology(referred to as"Fenlong technology").It makes the cultivated land and saline alkali land transformed into"sponge"farmland through"drill bit"vertically digging into the soil,one-time deep cultivation,not disturbing soil layer,and granulating the soil,to bring about the effects of"expanding the land,releasing the natural force,water conservation,disaster reduction,carbon reduction,tillage saving,fertilizer saving and grain increasing",and can broaden the space for human survival and development.It has been applied to more than 50 crops in 28 provinces,including Guangxi,Hebei and Tibet.Without increasing the use of fertilizer and water,the yield of varieties in cultivated land increased by 10%-50%,while that in saline and alkaline land increased by 20%-100%.The storage of natural precipitation increased by 100%,and drought,high temperature and low temperature decreased by 20%-30%,and carbon sequestration and emission reduction reached 20%.It is proposed that China can implement the"dual strategy"platform of farmland,saline alkali land,rivers and water bodies constructing the"incremental""five new warehouses"of grain,water,fish,sugar,etc.and"increased grain return"abroad,to ensure national security.
基金supported by the Fundamental Research Funds for the Central Universities of NUAA(No.kfjj20200414)Natural Science Foundation of Jiangsu Province in China(No.BK20181289).
文摘In this paper,we optimize the spectrum efficiency(SE)of uplink massive multiple-input multiple-output(MIMO)system with imperfect channel state information(CSI)over Rayleigh fading channel.The SE optimization problem is formulated under the constraints of maximum power and minimum rate of each user.Then,we develop a near-optimal power allocation(PA)scheme by using the successive convex approximation(SCA)method,Lagrange multiplier method,and block coordinate descent(BCD)method,and it can obtain almost the same SE as the benchmark scheme with lower complexity.Since this scheme needs three-layer iteration,a suboptimal PA scheme is developed to further reduce the complexity,where the characteristic of massive MIMO(i.e.,numerous receive antennas)is utilized for convex reformulation,and the rate constraint is converted to linear constraints.This suboptimal scheme only needs single-layer iteration,thus has lower complexity than the near-optimal scheme.Finally,we joint design the pilot power and data power to further improve the performance,and propose an two-stage algorithm to obtain joint PA.Simulation results verify the effectiveness of the proposed schemes,and superior SE performance is achieved.
基金supported by the National Natural Science Foundation of China(No.62071354)the Key Research and Development Program of Shaanxi(No.2022ZDLGY05-08)supported by the ISN State Key Laboratory。
文摘To meet the communication services with diverse requirements,dynamic resource allocation has shown increasing importance.In this paper,we consider the multi-slot and multi-user resource allocation(MSMU-RA)in a downlink cellular scenario with the aim of maximizing system spectral efficiency while guaranteeing user fairness.We first model the MSMURA problem as a dual-sequence decision-making process,and then solve it by a novel Transformerbased deep reinforcement learning(TDRL)approach.Specifically,the proposed TDRL approach can be achieved based on two aspects:1)To adapt to the dynamic wireless environment,the proximal policy optimization(PPO)algorithm is used to optimize the multi-slot RA strategy.2)To avoid co-channel interference,the Transformer-based PPO algorithm is presented to obtain the optimal multi-user RA scheme by exploring the mapping between user sequence and resource sequence.Experimental results show that:i)the proposed approach outperforms both the traditional and DRL methods in spectral efficiency and user fairness,ii)the proposed algorithm is superior to DRL approaches in terms of convergence speed and generalization performance.
基金supported by the National Science and Technology Major Project under Grant 2018ZX03001016
文摘Dynamic resource allocation(DRA) is a key technology to improve system performances in GEO multi-beam satellite systems. And, since the cache resource on the satellite is very valuable and limited, DRA problem under restricted cache resources is also an important issue to be studied. This paper mainly investigates the DRA problem of carrier resources under certain cache constraints. What's more, with the aim to satisfy all users' traffic demands as more as possible, and to maximize the utilization of the bandwidth, we formulate a multi-objective optimization problem(MOP) where the satisfaction index and the spectrum efficiency are jointly optimized. A modified strategy SA-NSGAII which combines simulated annealing(SA) and non-dominated sorted genetic algorithm-II(NSGAII) is proposed to approximate the Pareto solution to this MOP problem. Simulation results show the effectiveness of the proposed algorithm in terms of satisfaction index, spectrum efficiency, occupied cache, and etc.
文摘Space time coding can provide high data rate and performance gain for wireless communication system. Performance comparison of space time trellis codes and space time transmit diversity is carried out under the same bandwidth efficiency in this paper. We also propose some optimum low rate space time trellis codes in quasi static Rayleigh fading chan ̄nel. Performance analysis and simulation show that the low rate space time trellis codes outperform space time transmit diversity at the same bandwidth efficiency, and are more suitable for the power limited wireless communication system which has no strict requirement on bandwidth efficiency.
基金supported in part by the National Science Foundation(NSFC)for Distinguished Young Scholars of China with Grant 61625106the National Natural Science Foundation of China under Grant 61531011+1 种基金the Hong Kong,Macao and Taiwan Science and Technology Cooperation Program of China(2016YFE0123100)the Guangzhou University project under Grant 27000503123
文摘This paper investigates the achievable uplink spectral efficiency(SE) of a massive multi-input multi-output(MIMO) system with a mixed analog-to-digital converter(ADC) receiver architecture, in which some antennas are equipped with full-resolution ADCs while others are deployed with low-resolution ADCs. We derive the theoretical results and corresponding approximate expressions of the achievable SE in multi-cell systems with maximum ratio combining(MRC) detector and in single-cell systems with zero-forcing(ZF) detector. Based on approximated results, the effects of physical parameters, including the transmit power, the number of antennas, the proportion of full-resolution ADCs and the quantization precision of the low-resolution ADCs on the achievable SE are revealed. Furthermore, we propose the power allocation algorithms based on the lower bound and upper bound of approximate achievable SE. Our results show that the total achievable SE improves by increasing the number of BS antennas, the signal-to-noise ratio(SNR), and the quantization precision. Results showcase that proposed power allocation algorithms remarkably improve the total achievable SE comparing to the equal power allocation algorithm, which verifies the effectiveness of our proposed schemes.
基金Supported by Humanities and Social Sciences Project of the Ministry of Education(10YJC790111)
文摘The incompatibility of China's economy and finance has to some extent inhibited the development of rural economy. Taking Hubei Province for example,we measure the allocation efficiency of rural financial resources from the perspective of agricultural input and output,and use the modern rural financial development theory to set forth some policy recommendations on how to build a new rural financial resource allocation system. Studies have shown that the allocation efficiency of rural financial resources is low in China,and improving the allocation efficiency of rural financial resources is the key to perfecting rural financial environment while increasing financial support for agriculture.
基金Supported by the Grand from Tianjin Little Giant Fund under Grant No 14ZXLJGX00400the Tianjin Science and Technology Support Plan under Grant No 16YFZCGX00030
文摘Metamorphic In0.55Ga0.45P/In0.06Ga0.94As/Ge triple-junction (3J-MM) solar cells are grown on Ge (100) sub- strates via metal organic chemical vapor deposition. Epi-structural analyses such as high resolution x-ray diffrac- tion, photoluminence, cathodoluminescence and HRTEM are employed and the results show that the high crystal quality of 3J-MM solar cells is obtained with low threading dislocation density of graded buffer (an average value of 6.8× 10^4/cm2). Benefitting from the optimized bandgap combination, under one sun, AM0 spectrum, 25℃ conditions, the conversion efficiency is achieved about 32%, 5% higher compared with the lattice-matched In0.49Ga0.51P/In0.01Ga0.99As/Ge triple junction (3J-LM) solar cell. Under 1-MeV electron irradiation test, the degradation of the EQE and I-V characteristics of 3J-MM solar cells is at the same level as the 33-LM solar cell. The end-of-life efficiency is -27.1%. Therefore, the metamorphic triple-junction solar cell may be a promising candidate for next-generation space multi-junction solar cells.
基金Natural Science Foundation of Gansu Province(No.1506RJZA073)Construction Science and Technology Project of Gansu Province(No.JK2016-1021605)
文摘Based on grey neural network and particle swarm optimization algorithm,an automated stereo garage decision model is proposed to solve the problems of long waiting queue and low efficiency of automated parking garage.The gray neural network is used to forecast the stay time of the vehicle and particle swarm optimization algorithm is used to allocate the parking spaces in the stereo garage.The proposed stereo garage mathematical model is established on condition that vehicle arrival interval obeys Poisson distribution.The performance of stereo garage is evaluated by the average waiting time,average waiting queue length,average service time and average energy consumption of the customers.By comparing the efficiency indexes of the existing model based on near-distribution principle and the proposed model based on gray neural network and particle swarm algorithm,it is proved that the proposed model based on gray neural network and particle swarm algorithm is effective in improving the efficiency of garage operation and reducing the energy consumption of garage.
基金This project was supported by the National Natural Science Foundation of China (60272079) and the"863"High Tech-nology Research and Development Programof China (2003AA123310)
文摘An efficient spaee-time-frequency (STF) coding strategy for multi-input multi-output orthogonal frequency division multiplexing (MIMO-OFDM) systems is presented for high bit rate data transmission over frequency selective fading channels. The proposed scheme is a new approach to space-time-frequency coded OFDM (ODFDM) that combines OFDM with space-time coding, linear precoding and adaptive power allocation to provide higher quality of transmission in terms of the bit error rate performance and power efficiency. In addition to exploiting the maximux diversity gain in frequency, time and space, the proposed scheme enjoys high coding advantages and low-complexity decoding. The significant performance improvement of our design is confirned by corroborating numerical simulations.
文摘Biomass allocation and assimilation efficiency of natural Amour linden (Tilia amurensis) samplings in different light regimes were analyzed in the paper. The results showed that shoot increment of samplings in gap was the highest and that of samplings under canopy was the least. Samplings in gap expressed apical dominance strongly but samplings in full sun and under canopy behaved intensive branching. Lateral competition or moderate shading was favored to bole construction. The patters of biomass allocation of samplings in different light environment were rather similar. The biomass translocated to stem was more than that to other organs, and about one half of photosynthate was used to support leaf turn over. On the contrary, photosynthates of samplings in full sun were mostly consumed in leaves bearing and energy balancing. The carbon assimilation for leaves of samplings in gap was the most efficient, and more carbons were fixed and translocated to non-photosynthetic organs, especially to stemwood.
基金Supported by the Foundation of Huaian Industrial Projects(HAG2013064)the Foundation of Huaiyin Institute of Technology(HGB1202)the Doctoral Fund of Ministry of Education of China(20093218120021)
文摘A cross-layer design(CLD)scheme with combination of power allocation,adaptive modulation(AM)and automatic repeat request(ARQ)is presented for space-time coded MIMO system under imperfect feedback,and the corresponding system performance is investigated in a Rayleigh fading channel.Based on imperfect feedback information,a suboptimal power allocation(PA)scheme is derived to maximize the average spectral efficiency(SE)of the system.The scheme is based on a so-called compressed SNR criterion,and has a closed-form expression for positive power allocation,thus being computationally efficient.Moreover,it can improve SE of the presented CLD.Besides,due to better approximation,it obtains the performance close to the existing optimal approach which requires numerical search.Simulation results show that the proposed CLD with PA can achieve higher SE than the conventional CLD with equal power allocation scheme,and has almost the same performance as CLD with optimal PA.However,it has lower calculation complexity.
文摘The problem of the simultaneous multi-user resource allocation algorithm in orthogonal frequency division multiple access(OFDMA)based systems has recently attracted significant interest.However,most studies focus on maximizing the system throughput and spectral efficiency.As the green radio is essential in 5G and future networks,the energy efficiency becomes the major concern.In this paper,we develop four resource allocation schemes in the downlink OFDMA network and the main focus is on analyzing the energy efficiency of these schemes.Specifically,we employ the advanced multi-antenna technology in a multiple input-multiple output(MIMO)system.The first scheme is based on transmit spatial diversity(TSD),in which the vector channel with the highest gain between the base station(BTS)and specific antenna at the remote terminal(RT)is chosen for transmission.The second scheme further employs spatial multiplexing on the MIMO system to enhance the throughput.The space-division multiple-access(SDMA)scheme assigns single subcarrier simultaneously to RTs with pairwise“nearly orthogonal”spatial signatures.In the fourth scheme,we propose to design the transmit beamformers based on the zero-forcing(ZF)criterion such that the multi-user interference(MUI)is completely removed.We analyze the tradeoff between the throughput and power consumption and compare the performance of these schemes in terms of the energy efficiency.
基金by the National Natural Science Foundation of China for Young Scholars under Grant No.61701167.
文摘5G has pushed the use of radio spectrum to a new level,and cognitive clustering network can effectively improve the utilization of radio spectrum,which is a feasible way to solve the growing demand for wireless communications.However,cognitive clustering network is vulnerable to PUEA attack,which will lead to the degradation of system detection performance,thereby reducing the energy efficiency.Aiming at these problems,this paper investigates the optimal energy efficiency resource allocation scheme for cognitive clustering network under PUEA attack.A cooperative user selection algorithm based on selection factor is proposed to effectively resist PUEA user attack and improve detection performance.We construct the energy efficiency optimization problem under multi-constraint conditions and transform the nonlinear programming problem into parametric programming problem,which is solved by Lagrangian function and Karush-Kuhn-Tucker condition.Then the sub-gradient iterative algorithm based on optimal energy efficiency under PUEA attack is proposed and its complexity is analyzed.Simulation results indicate that proposed method is effective when subjected to PUEA attacks,and the impact of different parameters on energy efficiency is analyzed.
文摘Unlike most of the existing methods in Space Time coding (STC) system which focus on design of STC gaining full rate and/or maximum diversity, we propose an approach to improve spectral efficiency of the code. The proposed scheme carries more information symbols in each transmission block as compare to its counterpart code, and yet retains the property of simple decoding. Simulation results show that transmit diversity is retained with improvement of code efficiency. We mainly focus on Four transmit antenna scheme but it can be generalized for any number of transmit antennas.
基金The author is grateful to Dr Feng Yulong, the teachers and students at the Qujing normal university for enabling me to carry out this experiment. The study was founded by the Project of the National Natural Science Foundation of China (30670394), the Applied Basic Study Project of Yunnan Province (2007C107M),
文摘Invasion is often facilitated by high resources availabilities and suppressed under low resources habitats. However, a number of invasive plants can successfully establish and dominate in resource-poor and (or) the understory of closed forests, indicating the plant's performances are habitats-dependent and species-specific. It is therefore necessary to explore the ecophysiological characteristics associated invasiveness for one invasive species across multiple resources availabilities whilst taking the relatedness into these comparative studies. In this study, invasive Eupitorium adenophorum and its native congener E. japonicum grew under different resource gradients in terms of light levels and soil nitrogen additions to identify the functional significance morphological and physiological traits associated closely with invasion and to examine their comparative responses. Photosynthetic carbon gain, biomass allocation and resource-use efficiency are evaluated in this pot experiment. Across treatments, E. adenophorum exhibited consistently higher values for most of the morphological variables including plant stature, relative growth rate (RGR), leaf root ratio (LRR), leaf area ratio (LAR), total leaf area, and lower root: shoot ratio (RSR). Significantly higher Pmax corresponded with higher photosynthetic nitrogen use efficiency (PNUE) and photosynthetic energy use efficiency (PEUE) especially in low light and (or) unfertile condition. Higher Gs and Pmax but lower photosynthetic water use efficiency (WUE) indicated the trade-off relationship between WUE and PNUE for E. adenophorum. Final biomasses were higher for E. adenophorum in nutrient and(or) light limited conditions, in which higher leaf construction cost(CC) compared with E. japonicum could be over-compensated by its significantly higher assimilation rates. The effects of light levels on these plant attributes were stronger than soil nutrient contents. The responses of these two congeneric species to light and nitrogen availabilities were similar, but the differences were magnified in resources limited conditions, indicating the better performancer at acquiring and at using limited resources of E. adenophorum over its co-occurring native flora. Our study presented the distinctive advantages of E. adenophorum in resources-poor environments, indicating conventional strategy of managing resources levels to control the invasion and expending of exotic species may not be as effective as expected.
基金Supported by Student’s Platform for Innovation and Entrepreneurship Training Program at the State Level(202110414021)。
文摘Based on the existing literature,this paper analyzed and explored the factors that affect the efficiency of resource allocation,and evaluated the current situation of resource allocation in various fields.It is found that with the emergence of the new pattern of China’s economic development,the economic growth rate has slowed down,and the method of large-scale production driving economic growth is no longer applicable to the current economic situation.Nowadays,when structural transformation and upgrading have entered a new stage,to achieve the optimization of resource allocation efficiency,it is necessary to start from three aspects:improving information transparency,upgrading industrial structure,and planning government intervention.Through the adaptation analysis of blockchain technology and the existing problems in optimizing resource allocation efficiency,it explored the feasibility of blockchain technology to optimize resource allocation efficiency,and promote economical,efficient and high-quality development.
基金Supported by National Innovation Planning Project for University Students in 2021 (202110414021)
文摘With the rapid development of Internet technology,the importance of blockchain technology has become increasingly prominent.Faced with this situation,extensive research has been carried out at home and abroad.Through the analysis of relevant literature on blockchain in recent years,it is found that there are many research results of blockchain technology in medical care,finance,education,etc.,but its application in the field of resource allocation efficiency is rare.From the existing studies on the influencing factors of resource allocation efficiency in China,it is found that there are significant differences in resource allocation efficiency between China and some developed countries or between various provinces and cities of China.
文摘This article,which is based on panel data of Chinese state-owned industrial enterprises over the period 2006-2011,analyzes Labor reallocation Efficiency of State-Owned Enterprises with Syrquin's analysis of the total Reallocation effect of Resources. The results show that:①Labor allocation efficiency keeps a high level all the time;②The contribution that labor Reallocation efficiency makes to the growth of labor productivity has been at a low rate. Therefore, our government had better deepen the reform of state-owned enterprises and the evolvement of marketization
文摘Cognitive Radio(CR) is a promising technique for the next generation mobile communi-cation system for its capability to solve the conflicts between the scarcity and underutilization of spectrum.In this paper,aiming at maximizing the system capacity of a multi-antenna CR system on the premise that avoid interference to the primary system in the same band simultaneously,a resource allocation method which is able to avoid interference between PRimary(PR) and CR users by pro-jecting the transmit signals of CR users on the null space of the PR users' channels is proposed.CR users with better channel condition are selected,and the interference from CR system to PR users can be removed completely by projecting the transmit signals of CR system on the null-space of PR users' channels.Parallel sub-channels are constructed for CR users through Singular Value Decomposition(SVD).At last,waterfilling is also adopted to increase the CR users' capacity.Simulation result demonstrates that compared with existing methods,our method can improve the achievable sum rate of CR users as well as reduce the outage probability of PR users.