In this paper, a multi-channel self-interference cancellation (SIC) technique is proposed to reduce the size of AWS/PCS dual-band 5G FDD massive MIMO base station. Combining two bands with small frequency offset such as PCS and AWS bands in a base station requires modification of frequency duplex cavity filters to provide a wide passband with extremely narrow gap between the passband and the stop band. Such duplexer is hard to realize. We propose a novel multi-channel SIC to allow the dual-band operation with the same form factor as the single-band base station. A proof of concept (PoC) prototype is developed to demonstrate the feasibility of multi-channel SIC to this problem.

This paper presents the next evolution of FD-MIMO technology for beyond 5G, where antennas of the FD-MIMO system are placed in a distributed manner. This system, referred to as Distributed FD-MIMO (D-FD-MIMO) system, is capable of providing higher cell average throughput as well as more uniform user experience compared to the conventional FD-MIMO system. System level simulations results show that the proposed D-FD-MIMO system achieves 1.4 – 2 times cell average throughput gain compared to the FD-MIMO system. A proof of concept (PoC) system, which is developed for D-FD-MIMO, is presented. The UE assisted over-the-air (OTA) calibration, which is the most important process of D-FD-MIMO, is discussed. Finally, the field test results are presented.

反应堆保护系统用于监测与反应堆安全有关的物理和过程测量参数,确保在发生设计基准事故时自动触发紧急停堆和/或专设安全设施,从而保护反应堆中燃料包壳、一回路压力边界和安全壳的完整性,限制放射性物质向公众环境的释放.基于FirmSys平台,提出了应用于田湾5#、6#机组核电厂反应堆保护系统设计方案.详细介绍了系统结构、接口、多样性以及故障检测设计,并对保护系统设计方案与标准的符合性进行分析.分析结果表明,该系统设计方案满足单一故障、独立性、多样性、保护动作自动触发等安全设计准则,同时兼顾了电厂运行经济性,可为后续核电厂保护系统设计提供指导和借鉴.

As the pace of global 5G network deployments accelerates, now is the moment for the cellular industry to realize 6G cellular communication. In this article, modular massive multiple-in-put multiple-output (mmMIMO) is presented as one candidate technology for 6G to improve the spectral efficiency in low-frequency bands. The 5G New Radio pushed the boundary of the cellular system's operating frequency to high-frequen-cy bands, and this trend will continue in the 6G era. However, the technical advances in 5G for low-frequency bands fall short, although low-frequency bands are crucial in serving a large number of users in a wide coverage area. Although it would be ideal if massive MIMO could be utilized in low-frequency bands, it is less practical due to a large antenna form factor size. mmMIMO is a technology to distribute a large active antenna array with smaller standardized antenna modules, just like Lego-type building blocks. Through this, the benefits of massive MIMO can be achieved in low-frequency bands (e.g., sub-1 GHz), unconstrained by spatial limitations. In this article, the concept of mmMIMO, its applicability, and needed research efforts to standardize the technology for 6G are discussed. In addition, through the demonstration of a proof-of-concept system, it is shown that the technology can be within reach at the time of 6G commercialization around 2030. Lastly, the performance gain of mmMIMO is evidenced by system-level simulation.

为了解先进压水堆小破口失水事故下非能动安全壳冷却系统、非能动堆芯冷却系统、非能动余热排出系统的瞬态响应特性,需开展小破口失水事故下反应堆冷却剂系统和安全壳的耦合响应特性研究.分析结果表明,小破口失水事故下,耦合分析中非能动余热排出系统、非能动堆芯冷却系统、自动卸压系统和非能动安全壳冷却系统的特性与独立计算有较大差异,小破口失水事故下耦合分析得到的安全壳压力峰值小于独立计算.

Narrowband Internet of Things (NB-IoT) is a new technology being implemented into the Long-Term Evolution (LTE) standards to support machine-to-machine communications. Applications of IoT are expected to rapidly increase and to expand into many sectors. Increased number of IoT devices trying to access the medium with typically small data packets will overwhelm the network. Cognitive radios coupled with random access strategies can help alleviate excessive collisions in the network by many IoT access attempts. On the other hand, most IoT devices do not have hardware capabilities to perform sophisticated spectrum sensing methods over long durations. Therefore, it is important to reduce the spectrum sensing overhead while maximizing the NB-IoT network level throughput. In this paper, we derive a unique set of optimal sensing parameters which achieve the maximum throughput of a narrowband cognitive radio IoT (NB-CR-IoT) network. We show that accurate sensing from a single device perspective is not always the best solution for maximizing the throughput in an NB-CR-IoT network.

This study aims the throughput maximization of carrier sense multiple access (CSMA) in random access cognitive radio networks (CRNs) by using cooperative spectrum sensing. In the cooperative spectrum sensing, multiple cognitive radio (CR) users individually monitor the spectrum for the primary users (PUs)’ activities and send their local decisions to the CR access point. Upon receiving the individual decisions, the CR access point gives the final decision about the PU’s presence at the spectrum and sends it to all CR users in the network. At decision stage, CR access point utilizes the k-out-of-N decision fusion rule with optimal k value in order to obtain maximum CRN throughput. In this paper, we model a CRN utilizing CSMA medium access control scheme and focus on analyzing the throughput performance of it. Throughput performances of our CRN model which separately utilizes AND, OR, MAJORITY fusion rules and k-out-of-N decision fusion rule with the optimum k value are obtained and compared under the same network level probability of detection constraint. The throughput results obtained show that our CRN model utilizing k-out-of-N decision fusion rule with the optimum k value achieves higher throughput performance than AND, OR and MAJORITY fusion rules when they all have the same CRN load.

Massive multi-input multi-output (MIMO) is shown to significantly increase spectral efficiency by exploiting a large number of antennas to support high-order multiuser MIMO. In 3GPP Release-13, a full-dimension MIMO (FD-MIMO) technology was introduced to address practical aspects for massive MIMO in cellular systems; extensive simulations show 2–4 times capacity gain compared with current LTE systems. FD-MIMO has been identified as one of the key 5G technologies and is being continuously improved in 3GPP new radio standards. However, several practical challenges such as interference mitigation among MIMO streams for a large number of users with limited channel feedback, hardware limitations, such as calibration errors that limit the precoding capabilities need to be addressed carefully. A proof of concept (PoC) base-station and user equipment (UE) prototype has been designed to validate the potential of FD-MIMO technology and demonstrate commercial implementation feasibility. In this paper, we present theory and architecture behind an FD-MIMO prototype and share the field test results with LTE-based UEs in a multi-user MIMO setup. We also analyze the impact of transmitter and receiver calibration errors on the performance of the FD-MIMO system.

This paper presents the next evolution of FD-MIMO technology for beyond 5G, where antennas of the FD-MIMO system are placed in a distributed manner throughout the cell in a multi-cell deployment scenario. This system, referred to as Distributed FD-MIMO (D-FD-MIMO) system, is capable of providing higher cell average throughput as well as more uniform user experience compared to the conventional FD-MIMO system. System level simulations are performed to evaluate performance. Our results show that the proposed D-FD-MIMO system achieves 1.4-2 times cell average throughput gain compared to the FD-MIMO system. The insights of performance gain are provided. Hardware implementation challenges and potential standards impact are also presented.

通过对控制棒组件落棒过程、驱动机构勾爪动作和棒位探测器初级线圈响应的分析,提出自动进行落棒波形判断、分析和计算落棒时间的方法,并采用虚拟仪器技术予以实现.采用真实的落棒波形进行验证,表明该设计能够准确捕获落棒波形并自动进行落棒时间的计算.目前相关研究成果已经应用在海南昌江核电厂和福建福清核电厂3、4号机组上.

In this paper, we propose a maximum likelihood method for jointly estimating carrier frequency offset (CFO) and sampling frequency offset (SFO) in receivers for orthogonal frequency division multiplexing signals. The proposed estimator exploits the fact that a single source (such as a crystal oscillator or voltage controlled oscillator) is typically used in modern wireless receivers to provide a reference frequency for both the sampling clock and the radio frequency synthesizers. The proposed CFO estimator is capable of a large CFO estimation range (i.e., more than half of intercarrier spacing) without extending the length of the training sequence. The Cramer-Rao lower bound (CRLB) of the variance of the estimated joint CFO and SFO is derived and compared to the CRLBs of the CFO and SFO estimators in the literature. More importantly, the proposed method is validated on a real-time wireless test bed.

The paper describes the design of CRDM digital current adjustment equipment which is based on the transfer phase trigger theory. The current adjustment equipment is ameliorated through PID close loop control, the real time monitoring of time sequence current. For meeting the requirement of DAS, the current rack-off function is designed. The test result shows that the equipment meets the operation requirement of CRDM, and some technical points are optimized.

Full-Dimension MIMO (FD-MIMO) technology has been shown to increase spectral efficiency 2-4X compared to current LTE systems by exploiting a large number of antennas to support high order multiuser MIMO. High order multiuser MIMO with large number of antennas increase design and implementation complexity significantly. Furthermore, practical challenges such as antenna calibration for RF mismatches and failure need to be considered. In this paper, reduced-complexity precoding algorithm is introduced and optimized for real-time FPGA based implementation. Novel antenna calibration architecture is designed for FD-MIMO large 2-dimension array with the consideration of RF failure in practice. Field experimental results are also presented based on a proof of concept (PoC) FD-MIMO base-station (BS) with 32 antennas that supports up to 12 users and achieves spectral efficiency of ~21 bits/sec/Hz.

In order to study the affecting fac-tors of buffering,the 3D flow field of the hydraulic absorber,which was falling within guide cylinders of different structural sizes,was studied with the CFD code in the paper.The inner flow field and dynamic principle of the displacement,velocity and acceleration were obtained.The results indicated that different structural parameters such as the ab-sorber top diameter and the hole diameter at the bottom of the guide cylinder have significant influ-ence on buffering effect.

在方家山核电项目中，通过冗余通讯接口设计，实现了棒控棒位系统与DCS系统之间数据的正确、可靠传输，提高了系统可用性，实现了通过数字化DCS人机界面对棒控棒位系统进行控制及控制棒相关数据的数字化显示。

The cognitive radios (CR) utilize the spectrum resource without interfering the primary users (PU). Spectrum sensing, by which CR users detects the radio environment, is a critical technique in cognitive radios. Various collaborative spectrum sensing schemes are proposed to either improve sensing sensitivity or to reduce the sensing duration. However, most of the previous studies have not investigated the impact of sensing on the network level. Therefore, in this paper we investigate network level performance under ALOHA protocol while using autonomous sensing scheme where independent transmissions of CR users are allowed. We show that the optimal system level access throughput can be achieved by solving an optimization problem in terms of parameters configured for spectrum sensing and we also give the range of optimized throughput and the bound of optimal parameter value.

反应堆控制棒驱动机构电源控制装置采用闭环调节技术、脉宽调制技术以及可编程控制器控制技术,控制功能完备,实现了控制电路对绝缘栅双极型晶体管的有效控制,使得控制对象上的电流线性可调节,以及电流波形下降沿时间可调节.本装置采用的新的设计方法解决了基于传统国产控制棒驱动机构控制方法设计的装置和目前国外控制棒驱动机构电源控制装置存在的相关问题,与国内外同类控制设备相比主要性能基本一致,在控制技术、设备性能、可靠性和设备总体技术性能方面均达到国外同类先进产品的技术水平.

Switching operation happens extensively in nowadays wireless devices between various functional modules. The transient responses during the hardware switching are non-ideal due to the non-ideal behavior of hardware components. The non-ideal transient may cause distortion on signals and degenerate system performance before the transient effect is settling down. We explore the advanced solutions to compensate the transient impairments rather than, as the conventional treatment, inserting guard intervals. In this paper, we present the transient carrier frequency offset (CFO) observed in hardware testbeds built for wireless communications research, which are configured working in time division duplexing (TDD) mode. The transient CFO arises as a result of the switching between transmission and reception radio functions. The transient CFO cannot be estimated by the conventional CFO estimators because it is time varying. We present the modeling and estimation of the transient CFO in this paper. A weighted KumaresanTufts (KT) algorithm is proposed by exploiting both low-rank approximation and subspace structure to optimize the estimation of the transient CFO. We compare the proposed algorithm with the existing methods as well as the Crámer-Rao bound (CRB). The proposed algorithm is also confirmed by the experimental results obtained from the hardware testbed.