频率源相位噪声对频率步进雷达系统性能的影响

频率源是雷达系统的重要组成部分,其技术指标直接影响系统的性能.文中提出了基于频率源相位噪声的频率步进雷达系统的信号模型,讨论了频率源相位噪声对频率步进雷达系统性能的影响,并得出在满足系统性能的前提下对频率源相位噪声的要求,分析和仿真的结果对系统设计具有一定的指导意义.     

Personality and motivations associated with Facebook use

Facebook is quickly becoming one of the most popular tools for social communication. However, Facebook is somewhat different from other Social Networking Sites as it demonstrates an offline-to-online trend; that is, the majority of Facebook Friends are met offline and then added later. The present research investigated how the Five-Factor Model of personality relates to Facebook use. Despite some expected trends regarding Extraversion and Openness to Experience, results indicated that personality factors were not as influential as previous literature would suggest. The results also indicated that a motivation to communicate was influential in terms of Facebook use. It is suggested that different motivations may be influential in the decision to use tools such as Facebook, especially when individual functions of Facebook are being considered.     

Power System Stability Improvement by Using STATCOM with POC ＆ Excitation Controller

This paper presents the model of a static synchronous condenser （STATCOM） which is controlled externally by a newly designed power oscillation controller （POC） for the improvements of power system stability and damping effect of an on line power system. The proposed POC consists of two controllers （power oscillation damping ＆ proportional integral derivative PID ＆ POD）. PID parameters have been optimized by Zigler Necles close loop tuning method. Machine excitation has been controller by using excitation controller as required. Both single phase and three phase faults has been considered in the research. In this paper, a power system network is considered which is simulated in the phasor simulation method ＆ the network is simulated in three steps： without STATCOM, with STATCOM but no externally controlled, STATCOM with POC. Simulation result shows that without STATCOM, the system parameters become unstable during faults. When STATCOM is imposed in the network, then system parameters become stable. Again, when STATCOM is controlled externally by POC controllers, then system voltage ＆ power becomes stable in faster way then without controller It has been observed that the STATCOM ratings are only 20 MVA with controllers and 200 MVA without controllers. Therefore, STATCOM with POC controllers are more effective to enhance the voltage stability and increases power transmission capacity of a power system. So STATCOM with POC ＆ excitation controllers, the system performance is greatly enhanced.     

Characterization of proteomic changes in cardiac mitochondria in streptozotocin-diabetic rats using iTRAQ™ isobaric tags

Diabetes now affects more than 5% of the world's population and heart failure is the most common cause of death amongst diabetic patients. Accumulating evidence supports a view that myocardial mitochondrial structural and functional changes are central to the onset of diabetic heart failure, but the exact nature of these changes at the proteomic level remains unclear.Here we report on proteomic changes in diabetic rat heart mitochondria following 120 days of streptozotocin‐diabetes using the recently developed iTRAQ? labeling method, which permits quantification of proteins directly from complex mixtures, bypassing the limitations associated with gel‐based methods such as 2‐DE. Of 252 unique proteins identified, 144 were represented in at least three of six individual paired experiments. Relative amounts of 65 proteins differed significantly between the groups, confirming that the cardiac mitochondrial proteome is indeed impacted by diabetes. The most significant changes were increased protein levels of enzymes involved in mitochondrial oxidation of long‐chain fatty acids, which was also confirmed by enzyme assays, and decreased levels of multiple enzymes involved in oxidative phosphorylation and catabolism of short‐chain fatty acids and branched‐chain amino acids. We also found significant changes in levels of several enzymes linked to oxidative stress.     

Synthesis of polyblends from polypropylene and poly(R,S)‐β‐hydroxybutyrate,and their characterization

Blends of modified polypropylene (PP) with poly(R,S)‐β‐hydroxybutyrate (PHB) were prepared by casting polymer solutions, followed by compression molding into thin films. The modified polypropylene was obtained by oxidation with hydrogen peroxide. Oxidation of polypropylene produced new functional groups such as carbonyl and hydroxyl groups on the polymer chain, and a decrease in molecular weight and crystallinity of the polymers. Maximum crystallinity and mechanical properties of the polyblends were found with a PP/PHB ratio of 90/10 (w/w), and then decreased with increasing PHB content in the polyblends. Biodegradability of the polyblends was lower than that of bacterial and synthetic PHBs. Furthermore, an increase of PHB proportion in the polyblends resulted in highly non‐compatible polyblends. Hence only PHB and small parts of the polyblends were decomposed by microorganisms. Copyright © 2006 Society of Chemical Industry     

Treatment of phobic disorders using cognitive and exposure methods: A self-efficacy analysis.

Examined predictions derived from self-efficacy theory in comparing the effects of exposure and cognitive interventions with simple phobics. 22 phobics (25–64 yrs) with fears of either heights, elevators, or darkness were assigned to either guided exposure (GE) or cognitive restructuring (CR) treatments. GE was found significantly superior to CR in enhancing approach behavior, increasing level and strength of self-efficacy, reducing subjective fear, and decreasing physiological reactivity to imagined phobic scenes. High correlations were found between approach behavior and self-efficacy ratings for both groups. GE produced marked improvements in Ss' ability to cope with phobic situations in daily life. CR induced reported improvements in social functioning. At a 1-mo follow-up the results remained much the same. Five additional sessions of GE were then offered to Ss in the CR condition, producing results comparable to those of the original GE group. At a 6-mo follow-up all gains were maintained with further reductions in subjective fear for all GE Ss. (29 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Best of Both Worlds: Synergistically Derived Material Properties via Additive Manufacturing of Nanocomposites

With an exponential rise in the popularity and availability of additive manufacturing (AM), a large focus has been directed toward research in this topic's movement, while trying to distinguish themselves from similar works by simply adding nanomaterials to their process. Though nanomaterials can add impressive properties to nanocomposites (NCs), there are expansive amounts of opportunities that are left unexplored by simply combining AM with NCs without discovering synergistic effects and novel emerging material properties that are not possible by each of these alone. Cooperative, evolving properties of NCs in AM can be investigated at the processing, morphological, and architectural levels. Each of these categories are studied as a function of the amplifying relationship between nanomaterials and AM, with each showing the systematically selected material and method to advance the material performance, explore emergent properties, as well as improve the AM process itself. Innovative, advanced materials are key to faster development cycles in disruptive technologies for bioengineering, defense, and transportation sectors. This is only possible by focusing on synergism and amplification within additive manufacturing of nanocomposites.     

Hybrid coating pigments of poly(styrene-co-maleimide)/kaolin/alumina trihydrate for paper coating

Novel organic–inorganic hybrid pigments were prepared by in situ imidization of poly(styrene-co-maleic anhydride) (SMA) aqueous dispersion with ammonia in the presence of inorganic pigments, i.e. kaolin (K) or a mixture of kaolin (K)/alumina trihydrate (ATH). The objective was to allow the organic nano-particles of poly(styrene-co-maleimide) (SMI) to precipitate during their formation onto the surface of the inorganic pigment(s) and to investigate their potential in paper coatings. The produced hybrid pigments were characterized by Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFT-FTIR), scanning electron microscopy (SEM), wide-angel X-ray diffraction (WXRD) spectroscopy and their particle sizes were determined by dynamic light scattering technique. By FTIR measurements the formation of maleimide was confirmed and the existence of strong hydrogen bonding between organic and inorganic components could also be detected. Whereas, the SEM images revealed that the surface of silicate layers had successfully been to a large extent covered by the organic nano-particles to give raise to novel hybrid particles. In addition, the particle size measurements support the observation that the organic nanoparticles for the most part had been chemically or physically attached to the larger inorganic particles. Thus, this in situ imidization process in the presence of clay particles provides a neat method of dispersing the formed nanoparticles onto the inorganic surface through hydrogen bonding. The produced hybrids were applied as auxiliary pigments in paper coating where they improved gloss without roughening the paper surface.     

Observed communication in couples two years after integrative and traditional behavioral couple therapy: Outcome and link with five-year follow-up.

Objective: To examine changes in observed communication after therapy termination in distressed couples from a randomized clinical trial. Method: A total of 134 distressed couples were randomly assigned to either traditional behavioral couple therapy (TBCT; Jacobson & Margolin, 1979) or integrative behavioral couple therapy (IBCT; Jacobson & Christensen, 1998). Videotaped samples of each couple's interactions were coded from pre-therapy, post-therapy, and 2-year follow-up assessments. At these 3 time points, each partner chose 1 current relationship problem to discuss. Relationship satisfaction was assessed at 2-year follow-up, and clinically significant treatment response and marital status were assessed 5 years after treatment. Results: Observed negativity and withdrawal decreased from therapy termination through the 2-year follow-up as expected, but problem solving did not change, and observed positivity decreased. IBCT produced superior changes from post-therapy to the 2-year follow-up assessment compared with TBCT. Post-therapy levels and changes in communication over follow-up were associated with wife satisfaction at 2-year follow-up; only post-therapy to 2-year follow-up changes in communication were associated with husband satisfaction at 2-year follow-up. Post-therapy levels of problem solving and changes in wives' positivity from pre-therapy to post-therapy were associated with 5-year relationship outcomes. We found some counterintuitive results with positivity, but they were no longer significant after controlling for withdrawal. Conclusions: We found support for improvements in observed communication following treatment termination, with IBCT demonstrating greater maintenance of communication improvement over follow-up. We found limited evidence of associations between communication and relationship outcomes at 5-year follow-up. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

OptiCoat Duo Jet涂布头

借助OptiCoat Duo Jet涂布头的第三道涂布,可使液体包装纸板的质量能够满足光电苯胺凸版印刷法这一新型印刷方法的要求,并可生产新产品手提纸盒纸板.