传输腔稳频的397nm半导体激光器

商用的半导体激光器由于其长期漂移大,不能满足单离子光频标中离子的激光冷却和长时间探测的目的。因此,采用了传输腔稳频技术减小商用397nm半导体激光器的长期漂移。利用经过Pound-Drever-Hall(PDH)技术锁定的729nm超稳激光器作参考激光,采用扫描的法布里-珀罗(F-P)干涉仪作传输介质,实现了397nm半导体激光器的长稳锁定。稳频后397nm激光器在1h内的漂移小于1MHz,100s的Allan方差小于1×10-10。这些指标为下一步利用传输腔技术实现866nm激光的长稳锁定打下了基础,同时为优化单个钙离子的激光冷却和长时间精密测量提供了条件。     

A 77-GHz Phased-Array Transceiver With On-Chip Antennas in Silicon: Transmitter and Local LO-Path Phase Shifting

Integration of mm-wave multiple-antenna systems on silicon-based processes enables complex, low-cost systems for high-frequency communication and sensing applications. In this paper, the transmitter and LO-path phase-shifting sections of the first fully integrated 77-GHz phased-array transceiver are presented. The SiGe transceiver utilizes a local LO-path phase-shifting architecture to achieve beam steering and includes four transmit and receive elements, along with the LO frequency generation and distribution circuitry. The local LO-path phase-shifting scheme enables a robust distribution network that scales well with increasing frequency and/or number of elements while providing high-resolution phase shifts. Each element of the heterodyne transmitter generates +12.5 dBm of output power at 77 GHz with a bandwidth of 2.5 GHz leading to a 4-element effective isotropic radiated power (EIRP) of 24.5 dBm. Each on-chip PA has a maximum saturated power of +17.5 dBm at 77 GHz. The phased-array performance is measured using an internal test option and achieves 12-dB peak-to-null ratio with two transmit and receive elements active     

Destination-aware metric based social routing for mobile opportunistic networks

Wireless Networks - Although centrality is widely used to differentiate the importance of nodes for social-aware routing in mobile opportunistic networks (MONs), it is destination-agnostic since...     

油厂锅炉用水的分析检测

讨论了油厂锅炉水质检测的重要性。重点介绍了锅炉用水的要求和水质分析测定的方法。     

Further results on local stability of REM algorithm with time-varying delays

This letter presents some further results on the local stability in equilibrium for Internet congestion control algorithm proposed by Low et al., (IEEE/ACM Transactions on Networking, 1999). The propagation delay d(t) is assumed to be time-varying and have maximum and minimum delay bounds (i.e., d/sub m//spl les/d(t)/spl les/d/sub M/), which is more general than the assumption (0相似文献   

Alignment of a Perylene‐Based Ionic Self‐Assembly Complex in Thermotropic and Lyotropic Liquid‐Crystalline Phases

The thermotropic and lyotropic liquid‐crystalline (LC) phases of the ionic self‐assembled complex N,N′,‐bis(2‐(trimethylammonium)ethylene)‐perylene‐3,4,9,10‐tetracarboxyldiimide‐bis(2‐ethylhexyl)sulfosuccinate have been studied using polarizing microscopy, differential scanning calorimetry (DSC), and X‐ray scattering techniques. A two‐dimensional (2D) columnar thermotropic LC phase with π–π stacking of the perylene tectonic units and a lyotropic LC phase in dimethyl sulfoxide (DMSO) have been found. Different techniques have been applied to align both systems and included: surface interactions, electric and magnetic fields, shear force, and controlled domain formation at the LC–isotropic phase‐transition front (PTF). Characterization of the alignment in films has been performed using polarized UV‐vis spectroscopy and transmission null‐ellipsometry. The best results have been obtained for alignment of the material in a lyotropic phase by controlled domain formation at the PTF of the LC–isotropic phase transition. In this case, a dichroic ratio of 18 is achieved with packing of columns of perylenediimide tectons perpendicular to the PTF.     

瞬态热阻测试在贴片二极管在线测试中的应用

表面贴装整流极管的焊接质量直接影响其可靠性.提出了通过测试与瞬态热阻等价的热敏电压增量来评价焊接质量、筛选焊接不良的产品.利用TRR8000测试仪对样品进行合适条件下的在线筛选,能够有效剔出焊接不良产品,提高表面贴装整流二极管的可靠性.     

基于陶瓷材料及结构在水下航行器中的减振研究

从水下航行器艉段结构改进、陶瓷合金在水下航行器中的应用两方面对其减振进行了分析研究,结果表明:在壳体中部加肋板并加高航行器中肋板高度可减振近3 dB,而在壳体中部加肋板并将陶瓷合金应用在支撑架和壳体上的减振效果最好,比原艉段振动降低近5 dB。     

水下爆炸实验法在工业炸药JWL状态方程测定中的应用研究

为了方便可靠地测定工业炸药爆轰产物的JWL状态方程,基于压导式连续电阻丝探针设计柱形装药的水下爆炸斜冲击波测量系统,对工业改性铵油炸药(ANFO)进行3组水下爆炸实验,获得其爆轰波-冲击波时程曲线;通过对二维定常流场柱形装药水下爆炸的分析,得到斜冲击波阵面的轨迹,并求解出炸药的爆压、绝热指数、水气界面夹角等参数。以水中斜冲击波阵面和水气界面夹角的实验和模拟结果作为比较对象,通过调整Autodyn有限元分析程序中的JWL方程参数,最终测定出ANFO的JWL状态方程参数。模拟结果与实验结果一致性好,其中斜冲击波波阵面的误差均小于±5%,水气界面夹角的误差在±3%以内,表明所述水下爆炸实验对于大尺度工业炸药的JWL方程参数测定合理可靠。     

热塑性弹性体改性B炸药的性能研究

添加2%热塑性弹性体401和501对B炸药改性,得到改性后炸药MB-1和MB-2,测试了二者的力学性能和落锤撞击感度,分别用经验法和VLWR程序计算了二者的爆轰性能。结果表明,MB-1和MB-2的弹性和韧性均好于B炸药;在低速(100-1500s-1)冲击下,MB-2的韧性比MB-1好。大药片落锤撞击感度试验中,MB-1和MB-2的爆炸反应阈值高度分别为3.5-4m和6-6.5m,MB-1的撞击感度比MB-2高。与B炸药相比,MB-1和MB-2的爆速分别降低了0.104mm·μs-1和0.099mm·μs-1,爆压分别降低了1.3GPa和1.2GPa。