To acquire global navigation satellite system(GNSS)signals means four-dimension acquisition of bit transition,Doppler frequency,Doppler rate,and code phase in high-dynamic and weak signal environments,which needs a hi...To acquire global navigation satellite system(GNSS)signals means four-dimension acquisition of bit transition,Doppler frequency,Doppler rate,and code phase in high-dynamic and weak signal environments,which needs a high computational cost.To reduce the computations,this paper proposes a twostep compressed acquisition method(TCAM)for the post-correlation signal parameters estimation.Compared with the fast Fourier transform(FFT)based methods,TCAM uses fewer frequency search points.In this way,the proposed method reduces complex multiplications,and uses real multiplications instead of improving the accuracy of the Doppler frequency and the Doppler rate.Furthermore,the differential process between two adjacent milliseconds is used for avoiding the impact of bit transition and the Doppler frequency on the integration peak.The results demonstrate that due to the reduction of complex multiplications,the computational cost of TCAM is lower than that of the FFT based method under the same signal to noise ratio(SNR).展开更多
Aiming at the problem that indoor positioning technology based on wireless ultra-wideband pulse technology is susceptible to non-line-of-sight effects and multipath effects in confined spaces and weak signal environme...Aiming at the problem that indoor positioning technology based on wireless ultra-wideband pulse technology is susceptible to non-line-of-sight effects and multipath effects in confined spaces and weak signal environments,a high-precision positioning system based on UWB and IMU in a confined environment is designed.The STM32 chip is used as the main control,and the data information of IMU and UWB is fused by the fusion filtering algorithm.Finally,the real-time information of the positioning is transmitted to the host computer and the cloud.The experimental results show that the positioning accuracy and positioning stability of the system have been improved in the non-line-of-sight case of closed environment.The system has high positioning accuracy in a closed environment,and the components used are consumer-grade,which has strong practicability.展开更多
This study explores and seeks to explain the EIA procedures practice gap in Lao PDR. It reviews the literature and studies EIA legislation, administrative procedures, guidelines, and relevant documents by using a mode...This study explores and seeks to explain the EIA procedures practice gap in Lao PDR. It reviews the literature and studies EIA legislation, administrative procedures, guidelines, and relevant documents by using a model proposed by Leu et al. (1996) and applying criteria proposed by Wood (1995) to evaluate the performance of EIA systems. Key EIA legislation in Lao PDR has many strengths, but also major weaknesses: Inadequate planning procedures, no secondary regulations, few trained and skilled personnel, inadequate public consultation, lack of environmental data, weak follow-up and monitoring, and no enforcement machinery. Additionally, the EIA approval procedure is very bureaucratic and easily derailed by political and economic pressures. In addition, coordination among EIA proponents, consultants, concerned ministries, local authorities, planners, and decision-makers is generally weak. This delays decision-making and hinders implementation of environmental regulations. Thus, procedures and evaluation are not always performed well. EIAs are more a project justification tool than a project planning tool for sustainable development. We conclude with recommendations to strengthen the system, such as improving capacity building, implementing an EIA consultants’ accreditation system, ensuring effective public participation and access to EIA reports, applying systematic EIAs, reviewing criteria, and promoting environmental awareness.展开更多
基金supported by the National Natural Science Foundation of China(61901154,41704154)Zhejiang Province Science Foundation for Youths(LQ19F010006).
文摘To acquire global navigation satellite system(GNSS)signals means four-dimension acquisition of bit transition,Doppler frequency,Doppler rate,and code phase in high-dynamic and weak signal environments,which needs a high computational cost.To reduce the computations,this paper proposes a twostep compressed acquisition method(TCAM)for the post-correlation signal parameters estimation.Compared with the fast Fourier transform(FFT)based methods,TCAM uses fewer frequency search points.In this way,the proposed method reduces complex multiplications,and uses real multiplications instead of improving the accuracy of the Doppler frequency and the Doppler rate.Furthermore,the differential process between two adjacent milliseconds is used for avoiding the impact of bit transition and the Doppler frequency on the integration peak.The results demonstrate that due to the reduction of complex multiplications,the computational cost of TCAM is lower than that of the FFT based method under the same signal to noise ratio(SNR).
文摘Aiming at the problem that indoor positioning technology based on wireless ultra-wideband pulse technology is susceptible to non-line-of-sight effects and multipath effects in confined spaces and weak signal environments,a high-precision positioning system based on UWB and IMU in a confined environment is designed.The STM32 chip is used as the main control,and the data information of IMU and UWB is fused by the fusion filtering algorithm.Finally,the real-time information of the positioning is transmitted to the host computer and the cloud.The experimental results show that the positioning accuracy and positioning stability of the system have been improved in the non-line-of-sight case of closed environment.The system has high positioning accuracy in a closed environment,and the components used are consumer-grade,which has strong practicability.
文摘This study explores and seeks to explain the EIA procedures practice gap in Lao PDR. It reviews the literature and studies EIA legislation, administrative procedures, guidelines, and relevant documents by using a model proposed by Leu et al. (1996) and applying criteria proposed by Wood (1995) to evaluate the performance of EIA systems. Key EIA legislation in Lao PDR has many strengths, but also major weaknesses: Inadequate planning procedures, no secondary regulations, few trained and skilled personnel, inadequate public consultation, lack of environmental data, weak follow-up and monitoring, and no enforcement machinery. Additionally, the EIA approval procedure is very bureaucratic and easily derailed by political and economic pressures. In addition, coordination among EIA proponents, consultants, concerned ministries, local authorities, planners, and decision-makers is generally weak. This delays decision-making and hinders implementation of environmental regulations. Thus, procedures and evaluation are not always performed well. EIAs are more a project justification tool than a project planning tool for sustainable development. We conclude with recommendations to strengthen the system, such as improving capacity building, implementing an EIA consultants’ accreditation system, ensuring effective public participation and access to EIA reports, applying systematic EIAs, reviewing criteria, and promoting environmental awareness.
