基于LTE技术的战术通信系统研究进展

概述了民用移动通信发展过程,总结了LTE技术的技术优势和发展前景,提出了利 用LTE技术同步发展战术通信的新思想。目前战术通信已经不能满足多媒体业务发展的需求 ,逐步向着高速化、宽带化和网络化方向发展,美国战术通信发展很快,民用技术的军用化 扮演了重要角色。LTE技术符合战术通信的发展方向,但也存在移动性差、电波衰落大等问 题,通过采用频率下移变换、小型化设计等技术,可以有效解决这些问题。利用LTE技术发 展无线宽带战术通信具有十分重要意义,可以极大推动战术通信的发展,使战术通信发生根 本性变革、跨越式发展。     

低密度格码在OFDM系统中的应用与性能仿真

信道编码是OFDM系统的关键技术之一,低密度格码（Low Density Lattice Codes, L DLC）则是一种能高效译码且达到AWGN信道容量的新型编码技术,它兼具格码和低密度奇偶 校验码（Low Density Parity Codes, LDPC）的特点。基于LDLC码编译码原理,给出了LDLC 码作为前向纠错编码技术应用于OFDM系统的方案,在MATLAB平台下仿真研究了LDLC-OFDM系 统 在Rayleigh衰落信道下的性能,结果表明LDLC码很大程度地改善了OFDM系统的误码率性能, 且优于LDPC码。     

一种基于ADS的电调谐滤波器的新设计

设计了一种用于跳频通信系统接收机射频前端的UHF频段电调谐滤波器。使用安捷伦公司的 微波仿真软件ADS对电调谐滤波器进行结构设计和参数优化。对制成品的实际测试表明,该 调谐滤波器工作频段为225～400 MHz,3 dB带宽6.5～15 MHz,通带增益24～27 dB,矩形系 数小于6.2,其性能指标完全达到设计要求,在不同的频点都具有良好的电参数指标。所提 方法对电调滤波器的设计具有指导作用。     

采用低端FPGA实现直接数字频率合成的优化设计

当前大多数DDS实现方案要满足工程要求,成本和复杂度都很高。为此,提出一种基于 相位合成利用低端FPGA实现DDS的优化设计方案,介绍了其硬件和软件实现。 实测结果表明,所设计的DDS功耗低,输出信号频率稳定度高,频率转换速度快,输出频 点灵活,任意设置信号波形效果好,能普遍应用于通信调制、仪表检测、信号发生中。     

一种高效的OFDM载波频偏盲估计方法

针对正交频分复用（OFDM）系统,提出了一种低复杂度、高性能的载波频偏盲估计 方法。该方法充分利用载波频偏估计代价函数在一定区间内的单谷特性,采用黄金分割法搜 索载波频偏估计代价函数极值,从而大大降低其计算复杂度。最后对该方法和Tureli′s MU SIC-like(TML)载波频偏估计方法在加性高斯白噪声信道和多径信道环境下进行了仿真,结 果表明, 在同等条件下该方法的计算复杂度大大低于TML载波频偏估计方法。     

Accessing antecedents and outcomes of RFID implementation in health care

This research first conceptualizes, develops, and validates four constructs for studying RFID in health care, including Drivers (Internal and External), Implementation Level (Clinical Focus and Administrative Focus), Barriers (Cost Issues, Lack of Understanding, Technical Issues, and Privacy and Security Concerns), and Benefits (Patient Care, Productivity, Security and Safety, Asset Management, and Communication). Data for the study were collected from 88 health care organizations and the measurement scales were validated using structural equation modeling. Second, a framework is developed to discuss the causal relationships among the above mentioned constructs. It is found that Internal Drivers are positively related to Implementation Level, which in turn is positively related to Benefits and Performance. In addition, Barriers are found to be positively related to Implementation Level, which is in contrast to the originally proposed negative relationship. The research also compares perception differences regarding RFID implementation among the non-implementers, future implementers, and current implementers of RFID. It is found that both future implementers and current implementers consider RFID barriers to be lower and benefits to be higher compared to the non-implementers. This paper ends with our research implications, limitations and future research.     

Adherence,persistence, and inpatient utilization among adult schizophrenia patients using once-monthly versus twice-monthly long-acting atypical antipsychotics

Aims: This study compared healthcare resource utilization (HRU), healthcare costs, adherence, and persistence among adult patients with schizophrenia using once-monthly (OM) vs twice-monthly (TM) atypical long-acting injectable (LAI) antipsychotic (AP) therapy.

Materials and methods: A longitudinal retrospective cohort study was conducted using Medicaid claims data from six states. Patients initiated on aripiprazole or paliperidone palmitate were assigned to the OM cohort; risperidone-treated patients were assigned to the TM cohort. HRU and healthcare costs were assessed during the first 12 months following stabilization on the medication. Adherence was measured using the proportion of days covered (PDC) during the first year of follow-up. Persistence to the index medication was measured during the first 2 years following the index date. Comparison between the cohorts was achieved using multivariable generalized linear models, adjusting for demographic and clinical characteristics.

Results: Patients in the OM LAI cohort had lower inpatient HRU and medical costs when compared with patients in the TM cohort. Higher medical costs in the TM LAI cohort offset the higher pharmacy costs in the OM LAI cohort. Mean PDC during the first 12 months of follow-up was higher in the OM cohort than in the TM cohort (0.56 vs 0.50, p?<?.01). Median persistence was longer in the OM cohort than in the TM cohort (7.5 months vs 5.5 months), as was the hazard of discontinuing the index medication (hazard ratio?=?0.83, p?=?.01). Kaplan-Meier rates of persistence at 1 year were higher for OM patients than for TM patients (37.6% vs 29.6%, p?<?.01).

Limitations: This was a Medicaid sample with few aripiprazole LAI patients (5.4% of OM cohort). Medication use was inferred from pharmacy claims.

Conclusions: Among Medicaid patients in these six states, OM AP treatment was associated with lower HRU, better adherence and persistence, and similar total costs compared to patients on TM treatment.     

固态高功率高重频脉冲源的研究与发展

全固态高功率高重频脉冲源技术是定向能武器高能激光、高功率微波发展的关键技术之一。重点介绍了固态脉冲源技术发展历程和国内外发展动态。总结了三类固态高功率高重频脉冲源研制设计方法与工作原理、核心关键技术、应用前景、发展启示,以供相关人员参考。固态高功率高重频脉冲源具有全固态、高功率、小体积、轻重量、高可靠、长寿命等优点,在“激光打靶受控核爆模拟”实验研究、闪光X光照像、超宽带雷达、超宽谱通信、电子对抗、瞬态测量仪器等领域有广泛的应用前景。     

泛Kriging法在海上短波通信频率预测中的应用

频率预测是保障短波通信的关键技术。针对现有短波频率预测方法中数据处理过程复杂、输入参数条件苛刻、工程实现难度较大等问题,提出了一种基于泛克里格(Universal Kriging)空间重构法的海上短波通信频率预测方法。利用海军频率管理系统中大量的实用通信频率数据,基于球状模型、指数模型、高斯模型三种典型变异函数理论模型,研究了通信频率的空间相关性,建立了反映沿纬度方向通信频率变化剧烈程度的漂移表达式,通过交叉重构法对海上短波通信频率进行预测。实验结果表明,泛克里格法在海上短波通信频率预测中具有良好的适用性和可靠性,对未知海域短波通信频率的预测优选具有重要意义。     

OFDM系统的对数似然比最大化盲频偏估计算法

为了消除短波OFDM通信中的频率偏移问题,对差分OFDM信号进行了分析,并对最大 后验概率（MAP）译码的性质进行了研究,提出了一种似然比最大化的迭代盲频偏估计 算法。由于该算法充分利用了软译码得到的似然比信息,因此可以实现最优信号检测。计算 机仿真证明了该算法的有效性。进行了短波OFDM信号通信实验,得到了实测数据。实测数据 检测结果表明,该算法的误码率性能随着迭代次数的增加而提高,且一发两收系统性能要比 单发单收系统性能至少提高2 dB。