Non-orthogonal multiple access(NOMA) is considered as one of promising radio access techniques for visible light communications(VLC) in next-generation wireless communications systems.In order to provide theoretical s...Non-orthogonal multiple access(NOMA) is considered as one of promising radio access techniques for visible light communications(VLC) in next-generation wireless communications systems.In order to provide theoretical support for designing VLC-NOMA,we derive its analytic expressions for the symbol error rate(SER).Specifically,NOMA is first incorporated with appropriate VLC to establish a VLC-NOMA framework.Afterwards,mathematical expressions of the SER for the VLC-NOMA are developed.Moreover,numerical results are provided carefully to demonstrate that the proposed VLC-NOMA scheme outperforms than state-of-the-art orthogonal frequency division multiple access(OFDMA) one in terms of SER performance.Finally,relationships between the SER performance and the number of users,power allocation coefficient and semi-angle are well investigated,which can give us a scientific guide to devise the VLC-NOMA system for achieving better SER performance.展开更多
Storage and transportation of vegetable commercial seedlings becomes an important link along with the continuous expansion of planting areas of facility vegetables and vegetable seedling culture industry. In this stud...Storage and transportation of vegetable commercial seedlings becomes an important link along with the continuous expansion of planting areas of facility vegetables and vegetable seedling culture industry. In this study,pepper variety‘Nongda 24' was as the experimental material,and changes in the morphological and physiological indicators of plug seedlings in different low temperature( 6 and 11℃) and poor light environments were studied to find suitable storage environmental conditions. The results showed that pepper seedlings could be stored and transported for 14 days when storage temperature was 11℃ and light conditions such as light intensity and photoperiod were 30 μmol/( m^2·s)and 12 h/d by using a fluorescent lamp with R∶ B ratio of 1. 9,and 15 μmol/( m^2·s) and 24 h/d by using LED with R∶ B ratio of 1. 3,respectively. Moreover,the quality of pepper seedlings could be protected effectively. Compared to the fluorescent lamp,LED with high luminous efficiency and low energy consumption was suitable for the storage or long-distance transportation of pepper seedlings in low temperature and poor light environments.展开更多
A model to predict photosynthetic carbon assimilation rate(A)with high accuracy is important for forecasting crop yield and productivity.Long short-term memory(LSTM),a neural network suitable for time-series data,enab...A model to predict photosynthetic carbon assimilation rate(A)with high accuracy is important for forecasting crop yield and productivity.Long short-term memory(LSTM),a neural network suitable for time-series data,enables prediction with high accuracy but requires mesophyll variables.In addition,for practical use,it is desirable to have a technique that can predict A from easily available information.In this study,we propose a BLSTM augmented LSTM(BALSTM)model,which utilizes bi-directional LSTM(BLSTM)to indirectly reproduce the mesophyll variables required for LSTM.The most significant feature of the proposed model is that its hybrid architecture uses only three relatively easy-to-collect external environmental variables—photosynthetic photon flux density(Q_(in)),ambient CO_(2) concentration(C_(a)),and temperature(T_(air))—to generate mesophyll CO_(2) concentration(C_(i))and stomatal conductance to water vapor(g_(sw))as intermediate outputs.Then,A is predicted by applying the obtained intermediate outputs to the learning model.Accordingly,in this study,1)BALSTM(Q_(in),C_(a),T_(air))had a significantly higher A prediction accuracy than LSTM(Q_(in),C_(a),T_(air))in case of using only Q_(in),C_(a),and T_(air);2)BALSTMC_(i),g_(sw),which had C_(i) and g_(sw) as intermediate products,had the highest A prediction accuracy compared with other candidates;and 3)for samples where LSTM(Q_(in),C_(a),T_(air))had poor prediction accuracy,BALSTMC_(i),g_(sw)(Q_(in),C_(a),T_(air))clearly improved the results.However,it was found that incorrect predictions may be formed when certain factors are not reflected in the data(e.g.,timing,cultivar,and growth stage)or when the training data distribution that accounts for these factors differs from the predicted data distribution.Therefore,a robust model should be constructed in the future to improve the prediction accuracy of A by conducting gasexchange measurements(including a wide range of external environmental values)and by increasing the number of training data samples.展开更多
[Objectives]This study was conducted to investigate the effects of seeding rate and light on the seed yield and active ingredients of Vernonia anthelmintica.[Methods]With V.anthelmintica L.Willd as the research object...[Objectives]This study was conducted to investigate the effects of seeding rate and light on the seed yield and active ingredients of Vernonia anthelmintica.[Methods]With V.anthelmintica L.Willd as the research object,the seed yield was determined by staged harvesting combined with the actual cutting and measuring method;and the caffeoylquinic acids(CQA)were used as the characterization indexes,and high performance liquid chromatography was used to determine the contents of 3,4-CQA,3,5-CQA and 4,5-CQA of V.anthelmintica seeds under different seeding rate+light treatments,so as to compare the changes in seed yield and chemical composition of V.anthelmintica under different seeding rates and light factors.[Results]In Moyu County,Hetian and similar areas,the suitable planting rate of V.anthelmintica was in the range of 13.5-15.0 kg/hm^(2).For different harvesting purposes,the optimal seeding rate and light conditions of V.Anthelmintica were different.[Conclusions]The seeding rate and light conditions can be used to interfere with the seed yield and quality of V.anthelmintica.展开更多
[Objectives]This study aimed to investigate the effect of sowing rate,fertilizer amount and light on yield of Cichorium glandulosum Boiss.et Huet.[Methods]The Latin square design was adopted to investigate the effect ...[Objectives]This study aimed to investigate the effect of sowing rate,fertilizer amount and light on yield of Cichorium glandulosum Boiss.et Huet.[Methods]The Latin square design was adopted to investigate the effect of sowing rate+fertilizer amount,sowing rate+light on root and seed yield of C.glandulosum Boiss.et Huet.The changes in the seed and root yield of C.glandulosum Boiss.et Huet.under the influence of sowing rate,N application rate and light were compared and analyzed.[Results]In Moyu,Hotan and similar areas,the suitable sowing rate of C.glandulosum Boiss.et Huet.was 4.5-15.0 kg/ha.Without applying fertilizer,if the main purpose is to harvest the roots,the sowing rate of C.glandulosum Boiss.et Huet.is recommended to be 7.5-15.0 kg/ha;and if the main purpose is to harvest the seeds,the sowing rate is recommended to be 4.5-7.5 kg/ha.Shading will affect the root and seed yield.At the fertilizer amount of 450 kg/ha,the optimal sowing rate of C.glandulosum Boiss.et Huet.is 4.5 kg/ha.[Conclusions]This study provides a certain reference basis for artificial cultivation of C.glandulosum Boiss.et Huet.展开更多
Visible light communication(VLC)has a paramount role in industrial implementations,especially for better energy efficiency,high speed-data rates,and low susceptibility to interference.However,since studies on VLC for ...Visible light communication(VLC)has a paramount role in industrial implementations,especially for better energy efficiency,high speed-data rates,and low susceptibility to interference.However,since studies on VLC for industrial implementations are in scarcity,areas concerning illumination optimisation and communication performances demand further investigation.As such,this paper presents a new modelling of light fixture distribution for a warehouse model to provide acceptable illumination and communication performances.The proposed model was evaluated based on various semi-angles at half power(SAAHP)and different height levels for several parameters,including received power,signal to noise ratio(SNR),and bit error rate(BER).The results revealed improvement in terms of received power and SNR with 30 Mbps data rate.Various modulations were studied to improve the link quality,whereby better average BER values of 5.55×10^(−15) and 1.06×10^(−10) had been achieved with 4 PAM and 8 PPM,respectively.The simulation outcomes are indeed viable for the practical warehouse model.展开更多
Visible light communication(VLC),which is a prominent emerging solution that complements the radio frequency(RF)technology,exhibits the potential to meet the demands of fifth-generation(5G)and beyond technologies.The ...Visible light communication(VLC),which is a prominent emerging solution that complements the radio frequency(RF)technology,exhibits the potential to meet the demands of fifth-generation(5G)and beyond technologies.The random movement of mobile terminals in the indoor environment is a challenge in the VLC system.The model of optical attocells has a critical role in the uniform distribution and the quality of communication links in terms of received power and signal-to-noise ratio(SNR).As such,the optical attocells positions were optimized in this study with a developed try and error(TE)algorithm.The optimized optical attocells were examined and compared with previous models.This novel approach had successfully increased minimum received power from−1.29 to−0.225 dBm,along with enhanced SNR performance by 2.06 dB.The bit error rate(BER)was reduced to 4.42×10−8 and 6.63×10−14 by utilizing OOK-NRZ and BPSK modulation techniques,respectively.The optimized attocells positions displayed better uniform distribution,as both received power and SNR performances improved by 0.45 and 0.026,respectively.As the results of the proposed model are optimal,it is suitable for standard office and room model applications.展开更多
During in vitro fertilization, human embryos are incubated without light, and these conditions do not ensure embryo survival. This study explored whether environmental conditions can influence the embryo viability rat...During in vitro fertilization, human embryos are incubated without light, and these conditions do not ensure embryo survival. This study explored whether environmental conditions can influence the embryo viability rates of the house cricket, Acheta domesticus. In particular, the experiment tested what colors of visible light provide the best incubation conditions to ensure cricket embryo viability. The concept was to use house cricket embryos to represent human embryos. Cricket embryos were chosen as their eggs have soft outer membrane casings and resemble human embryos during the first few days after fertilization. During the experiment, the adult crickets laid their eggs into one of six soil-filled boxes called substrates. Each substrate was placed into one of six storage containers filled with adult crickets and lit with a different colored visible light (red, yellow, green, blue, white, or no light). After two days of breeding, the egg-filled substrates were removed from the adult crickets and placed in another storage container of the same color light. After incubation under heat-emitting lamps and under one of six light colors, nymphs were counted after hatching to determine embryo viability. After three trials, the red light provided the significantly highest viability rate, with yellow and no light being comparable seconds. The green, blue, and white lights showed significantly lower viability rates than no visible light. My results raise the speculation that exposing fertilized mammal eggs to visible light colors might have the same effects during the in vitro fertilization process.展开更多
本文设计了一个多输入单输出(Multiple-Input Single-Output,MISO)的三维室内可见光定位通信一体化(Visible Light Position and Communication,VLPC)系统,该系统在接收端基于接收信号强度(Received Signal Strength,RSS)的三维可见光定...本文设计了一个多输入单输出(Multiple-Input Single-Output,MISO)的三维室内可见光定位通信一体化(Visible Light Position and Communication,VLPC)系统,该系统在接收端基于接收信号强度(Received Signal Strength,RSS)的三维可见光定位(Visible Light Position,VLP)算法获得定位数据,同时估计信道状态信息(Channel State Information,CSI)并上传给发射端进行定向通信.该系统的发射端基于空移键控(Space Shift Keying,SSK)的室内可见光通信(Visible Light Communication,VLC)技术实现系统的通信功能.另外,本方案可以完全避免通信与定位子系统之间的干扰.同时,通过推导定位误差的克拉美罗下界(Cramér-Rao Lower Bound,CRLB)和SSK-VLC的通信可达速率来评估本文提出的VLPC系统的性能.仿真结果验证了本文所提方案的有效性.展开更多
在基于非正交多址接入技术的多用户下行室内可见光通信(Visible light communication system based on non⁃orthogonal multiple access technology,VLC⁃NOMA)系统中,针对和速率与用户公平性冲突的问题,提出一种基于加权和速率最大化的...在基于非正交多址接入技术的多用户下行室内可见光通信(Visible light communication system based on non⁃orthogonal multiple access technology,VLC⁃NOMA)系统中,针对和速率与用户公平性冲突的问题,提出一种基于加权和速率最大化的迭代功率分配方案。该方案以最大化加权和速率为目标,可通过改变权重因子来调节用户公平性。由于目标问题属于非凸优化问题,通过辅助变量法和凸优化理论将该非凸问题转化为凹问题,再通过拉格朗日对偶法进行求解,并根据问题的解设计了一种迭代功率分配算法。对所提算法的收敛性、系统和速率以及用户公平性进行了仿真。结果表明,所提迭代功率分配算法具有良好的收敛性,相较于VLC⁃OMA系统,VLC⁃NOMA系统能够获得更好的和速率性能。通过调整权重因子,在牺牲较小系统和速率的情况下能够获得比现有功率分配方案更好的系统和速率与用户公平性。展开更多
家禽是长日照动物,科学合理的光照程序对蛋鸡的生长发育、性成熟、开产日龄、产蛋高峰等都有显著影响,在诱导换羽的禁食和恢复采食的不同阶段,设定相应的光照程序对于提升诱导换羽效果具有重要的意义。该研究选用529日龄体重相近、产蛋...家禽是长日照动物,科学合理的光照程序对蛋鸡的生长发育、性成熟、开产日龄、产蛋高峰等都有显著影响,在诱导换羽的禁食和恢复采食的不同阶段,设定相应的光照程序对于提升诱导换羽效果具有重要的意义。该研究选用529日龄体重相近、产蛋率约为60%的贵妃蛋鸡为试验材料,根据禁食诱导换羽的不同时期,将光照制度的变化分4个阶段,并于第Ⅰ阶段(16 h L/8 h D,禁食前)、第Ⅱ阶段(8 h L/16 h D持续3 d)、第Ⅲ阶段(10 h L/14 h D持续13 d)的最后1天(F 0、F 3、F 16)和第Ⅳ阶段(逐渐增加光照0.5 h/d至恢复到16 h L/8 h D)的第6、32天(R 6、R 32)5个不同时期屠宰采样,通过卵泡数量、卵巢抗氧化指标、KIT-PI3K-PTEN-AKT信号通路和GDF9基因表达量等来探究光照程序在禁食诱导换羽过程的作用。结果表明,缩短光照蛋鸡血清中生殖激素FSH、LH、E 2和P 4的水平降低(P<0.001),超氧化物歧化酶(P<0.05)、谷胱甘肽过氧化酶(P<0.001)活力增强,在此过程中原始卵泡可能被激活,使小黄卵泡(P<0.01)、大白卵泡(P>0.05)的数量增多;逐渐恢复光照时长过程中KIT和PI3K处于持续高表达状态(P<0.001),PTEN相对表达量降低(P<0.01),而AKT相对表达量基本不变(P>0.05),且血清中生殖激素水平和卵巢抗氧化水平恢复到初始状态,但整体卵泡数量有所上升。该结果表明在禁食换羽过程中科学合理的光照程序对卵巢功能的重塑具有辅助作用。展开更多
基金supported by National Natural Science Foundation of China grants(No.61401069,No.61271240,No.61501254)Jiangsu Specially Appointed Professor Grant(RK002STP16001)+2 种基金Innovation and Entrepreneurship of Jiangsu High-level Talent Grant(CZ0010617002)High-level talent startup grant of Nanjing University of Posts and Telecommunications(XK0010915026)“1311 Talent Plan” of Nanjing University of Posts and Telecommunications
文摘Non-orthogonal multiple access(NOMA) is considered as one of promising radio access techniques for visible light communications(VLC) in next-generation wireless communications systems.In order to provide theoretical support for designing VLC-NOMA,we derive its analytic expressions for the symbol error rate(SER).Specifically,NOMA is first incorporated with appropriate VLC to establish a VLC-NOMA framework.Afterwards,mathematical expressions of the SER for the VLC-NOMA are developed.Moreover,numerical results are provided carefully to demonstrate that the proposed VLC-NOMA scheme outperforms than state-of-the-art orthogonal frequency division multiple access(OFDMA) one in terms of SER performance.Finally,relationships between the SER performance and the number of users,power allocation coefficient and semi-angle are well investigated,which can give us a scientific guide to devise the VLC-NOMA system for achieving better SER performance.
基金Supported by National Key Research and Development Program of China(2017YFB0403901)
文摘Storage and transportation of vegetable commercial seedlings becomes an important link along with the continuous expansion of planting areas of facility vegetables and vegetable seedling culture industry. In this study,pepper variety‘Nongda 24' was as the experimental material,and changes in the morphological and physiological indicators of plug seedlings in different low temperature( 6 and 11℃) and poor light environments were studied to find suitable storage environmental conditions. The results showed that pepper seedlings could be stored and transported for 14 days when storage temperature was 11℃ and light conditions such as light intensity and photoperiod were 30 μmol/( m^2·s)and 12 h/d by using a fluorescent lamp with R∶ B ratio of 1. 9,and 15 μmol/( m^2·s) and 24 h/d by using LED with R∶ B ratio of 1. 3,respectively. Moreover,the quality of pepper seedlings could be protected effectively. Compared to the fluorescent lamp,LED with high luminous efficiency and low energy consumption was suitable for the storage or long-distance transportation of pepper seedlings in low temperature and poor light environments.
基金the support of JST PRESTO(Grant No.JPMJPR16O3)JSPS KAKENHI(Grant Nos.16KK0169 and 19K15944).
文摘A model to predict photosynthetic carbon assimilation rate(A)with high accuracy is important for forecasting crop yield and productivity.Long short-term memory(LSTM),a neural network suitable for time-series data,enables prediction with high accuracy but requires mesophyll variables.In addition,for practical use,it is desirable to have a technique that can predict A from easily available information.In this study,we propose a BLSTM augmented LSTM(BALSTM)model,which utilizes bi-directional LSTM(BLSTM)to indirectly reproduce the mesophyll variables required for LSTM.The most significant feature of the proposed model is that its hybrid architecture uses only three relatively easy-to-collect external environmental variables—photosynthetic photon flux density(Q_(in)),ambient CO_(2) concentration(C_(a)),and temperature(T_(air))—to generate mesophyll CO_(2) concentration(C_(i))and stomatal conductance to water vapor(g_(sw))as intermediate outputs.Then,A is predicted by applying the obtained intermediate outputs to the learning model.Accordingly,in this study,1)BALSTM(Q_(in),C_(a),T_(air))had a significantly higher A prediction accuracy than LSTM(Q_(in),C_(a),T_(air))in case of using only Q_(in),C_(a),and T_(air);2)BALSTMC_(i),g_(sw),which had C_(i) and g_(sw) as intermediate products,had the highest A prediction accuracy compared with other candidates;and 3)for samples where LSTM(Q_(in),C_(a),T_(air))had poor prediction accuracy,BALSTMC_(i),g_(sw)(Q_(in),C_(a),T_(air))clearly improved the results.However,it was found that incorrect predictions may be formed when certain factors are not reflected in the data(e.g.,timing,cultivar,and growth stage)or when the training data distribution that accounts for these factors differs from the predicted data distribution.Therefore,a robust model should be constructed in the future to improve the prediction accuracy of A by conducting gasexchange measurements(including a wide range of external environmental values)and by increasing the number of training data samples.
基金Autonomous Region Science and Technology Supporting Xinjiang Project Plant Project(2016E02007)the West Light Foundation of The Chinese Academy of Sciences(2019-FPGGRC-004).
文摘[Objectives]This study was conducted to investigate the effects of seeding rate and light on the seed yield and active ingredients of Vernonia anthelmintica.[Methods]With V.anthelmintica L.Willd as the research object,the seed yield was determined by staged harvesting combined with the actual cutting and measuring method;and the caffeoylquinic acids(CQA)were used as the characterization indexes,and high performance liquid chromatography was used to determine the contents of 3,4-CQA,3,5-CQA and 4,5-CQA of V.anthelmintica seeds under different seeding rate+light treatments,so as to compare the changes in seed yield and chemical composition of V.anthelmintica under different seeding rates and light factors.[Results]In Moyu County,Hetian and similar areas,the suitable planting rate of V.anthelmintica was in the range of 13.5-15.0 kg/hm^(2).For different harvesting purposes,the optimal seeding rate and light conditions of V.Anthelmintica were different.[Conclusions]The seeding rate and light conditions can be used to interfere with the seed yield and quality of V.anthelmintica.
基金Supported by Science and Technology Support Project of Xinjiang Uygur Autonomous Region(2016E02007)Western Young Scholars Project of Chinese Academy of Sciences(2018-XBQNXZ-A-002)
文摘[Objectives]This study aimed to investigate the effect of sowing rate,fertilizer amount and light on yield of Cichorium glandulosum Boiss.et Huet.[Methods]The Latin square design was adopted to investigate the effect of sowing rate+fertilizer amount,sowing rate+light on root and seed yield of C.glandulosum Boiss.et Huet.The changes in the seed and root yield of C.glandulosum Boiss.et Huet.under the influence of sowing rate,N application rate and light were compared and analyzed.[Results]In Moyu,Hotan and similar areas,the suitable sowing rate of C.glandulosum Boiss.et Huet.was 4.5-15.0 kg/ha.Without applying fertilizer,if the main purpose is to harvest the roots,the sowing rate of C.glandulosum Boiss.et Huet.is recommended to be 7.5-15.0 kg/ha;and if the main purpose is to harvest the seeds,the sowing rate is recommended to be 4.5-7.5 kg/ha.Shading will affect the root and seed yield.At the fertilizer amount of 450 kg/ha,the optimal sowing rate of C.glandulosum Boiss.et Huet.is 4.5 kg/ha.[Conclusions]This study provides a certain reference basis for artificial cultivation of C.glandulosum Boiss.et Huet.
基金supported by Professional Development Research University Grant(UTM Vot No.06E59).
文摘Visible light communication(VLC)has a paramount role in industrial implementations,especially for better energy efficiency,high speed-data rates,and low susceptibility to interference.However,since studies on VLC for industrial implementations are in scarcity,areas concerning illumination optimisation and communication performances demand further investigation.As such,this paper presents a new modelling of light fixture distribution for a warehouse model to provide acceptable illumination and communication performances.The proposed model was evaluated based on various semi-angles at half power(SAAHP)and different height levels for several parameters,including received power,signal to noise ratio(SNR),and bit error rate(BER).The results revealed improvement in terms of received power and SNR with 30 Mbps data rate.Various modulations were studied to improve the link quality,whereby better average BER values of 5.55×10^(−15) and 1.06×10^(−10) had been achieved with 4 PAM and 8 PPM,respectively.The simulation outcomes are indeed viable for the practical warehouse model.
基金the grant names“ProfessionalDevelopment Research University Grant”(“UTM Vot No.05E69”and“TDR grant Vot No.05G27”).
文摘Visible light communication(VLC),which is a prominent emerging solution that complements the radio frequency(RF)technology,exhibits the potential to meet the demands of fifth-generation(5G)and beyond technologies.The random movement of mobile terminals in the indoor environment is a challenge in the VLC system.The model of optical attocells has a critical role in the uniform distribution and the quality of communication links in terms of received power and signal-to-noise ratio(SNR).As such,the optical attocells positions were optimized in this study with a developed try and error(TE)algorithm.The optimized optical attocells were examined and compared with previous models.This novel approach had successfully increased minimum received power from−1.29 to−0.225 dBm,along with enhanced SNR performance by 2.06 dB.The bit error rate(BER)was reduced to 4.42×10−8 and 6.63×10−14 by utilizing OOK-NRZ and BPSK modulation techniques,respectively.The optimized attocells positions displayed better uniform distribution,as both received power and SNR performances improved by 0.45 and 0.026,respectively.As the results of the proposed model are optimal,it is suitable for standard office and room model applications.
文摘During in vitro fertilization, human embryos are incubated without light, and these conditions do not ensure embryo survival. This study explored whether environmental conditions can influence the embryo viability rates of the house cricket, Acheta domesticus. In particular, the experiment tested what colors of visible light provide the best incubation conditions to ensure cricket embryo viability. The concept was to use house cricket embryos to represent human embryos. Cricket embryos were chosen as their eggs have soft outer membrane casings and resemble human embryos during the first few days after fertilization. During the experiment, the adult crickets laid their eggs into one of six soil-filled boxes called substrates. Each substrate was placed into one of six storage containers filled with adult crickets and lit with a different colored visible light (red, yellow, green, blue, white, or no light). After two days of breeding, the egg-filled substrates were removed from the adult crickets and placed in another storage container of the same color light. After incubation under heat-emitting lamps and under one of six light colors, nymphs were counted after hatching to determine embryo viability. After three trials, the red light provided the significantly highest viability rate, with yellow and no light being comparable seconds. The green, blue, and white lights showed significantly lower viability rates than no visible light. My results raise the speculation that exposing fertilized mammal eggs to visible light colors might have the same effects during the in vitro fertilization process.
文摘本文设计了一个多输入单输出(Multiple-Input Single-Output,MISO)的三维室内可见光定位通信一体化(Visible Light Position and Communication,VLPC)系统,该系统在接收端基于接收信号强度(Received Signal Strength,RSS)的三维可见光定位(Visible Light Position,VLP)算法获得定位数据,同时估计信道状态信息(Channel State Information,CSI)并上传给发射端进行定向通信.该系统的发射端基于空移键控(Space Shift Keying,SSK)的室内可见光通信(Visible Light Communication,VLC)技术实现系统的通信功能.另外,本方案可以完全避免通信与定位子系统之间的干扰.同时,通过推导定位误差的克拉美罗下界(Cramér-Rao Lower Bound,CRLB)和SSK-VLC的通信可达速率来评估本文提出的VLPC系统的性能.仿真结果验证了本文所提方案的有效性.
文摘在基于非正交多址接入技术的多用户下行室内可见光通信(Visible light communication system based on non⁃orthogonal multiple access technology,VLC⁃NOMA)系统中,针对和速率与用户公平性冲突的问题,提出一种基于加权和速率最大化的迭代功率分配方案。该方案以最大化加权和速率为目标,可通过改变权重因子来调节用户公平性。由于目标问题属于非凸优化问题,通过辅助变量法和凸优化理论将该非凸问题转化为凹问题,再通过拉格朗日对偶法进行求解,并根据问题的解设计了一种迭代功率分配算法。对所提算法的收敛性、系统和速率以及用户公平性进行了仿真。结果表明,所提迭代功率分配算法具有良好的收敛性,相较于VLC⁃OMA系统,VLC⁃NOMA系统能够获得更好的和速率性能。通过调整权重因子,在牺牲较小系统和速率的情况下能够获得比现有功率分配方案更好的系统和速率与用户公平性。
文摘家禽是长日照动物,科学合理的光照程序对蛋鸡的生长发育、性成熟、开产日龄、产蛋高峰等都有显著影响,在诱导换羽的禁食和恢复采食的不同阶段,设定相应的光照程序对于提升诱导换羽效果具有重要的意义。该研究选用529日龄体重相近、产蛋率约为60%的贵妃蛋鸡为试验材料,根据禁食诱导换羽的不同时期,将光照制度的变化分4个阶段,并于第Ⅰ阶段(16 h L/8 h D,禁食前)、第Ⅱ阶段(8 h L/16 h D持续3 d)、第Ⅲ阶段(10 h L/14 h D持续13 d)的最后1天(F 0、F 3、F 16)和第Ⅳ阶段(逐渐增加光照0.5 h/d至恢复到16 h L/8 h D)的第6、32天(R 6、R 32)5个不同时期屠宰采样,通过卵泡数量、卵巢抗氧化指标、KIT-PI3K-PTEN-AKT信号通路和GDF9基因表达量等来探究光照程序在禁食诱导换羽过程的作用。结果表明,缩短光照蛋鸡血清中生殖激素FSH、LH、E 2和P 4的水平降低(P<0.001),超氧化物歧化酶(P<0.05)、谷胱甘肽过氧化酶(P<0.001)活力增强,在此过程中原始卵泡可能被激活,使小黄卵泡(P<0.01)、大白卵泡(P>0.05)的数量增多;逐渐恢复光照时长过程中KIT和PI3K处于持续高表达状态(P<0.001),PTEN相对表达量降低(P<0.01),而AKT相对表达量基本不变(P>0.05),且血清中生殖激素水平和卵巢抗氧化水平恢复到初始状态,但整体卵泡数量有所上升。该结果表明在禁食换羽过程中科学合理的光照程序对卵巢功能的重塑具有辅助作用。
