分米波分放式电视发射机伴间电子管功率放大器的理论简析与实践

本文从理论上简要地分析了在分米波段，伴音电子管功放因回路高频损耗带来的一些特殊问题，提出了解决分米波段伴间电子管功放因回路热失谐所致的输出功率不稳定及腔体温升过大等问题的办法，并通过实验证实了其正确性，进一步提供实际调试时一些必要的数据。解决了分米波１０ＫＷ分放式发射机研制中的一个技术难题。

三吊臂分吊合放式起重装置设计

针对吊装过程中,有时需要有选择性地将集装箱有序放置这一问题,提出了三吊臂分吊合放式起重装置的整体设计方案。在机械部分方案设计中,应用TRIZ创新理论,化解了方案设计阶段的矛盾冲突,提出了将电机做配重的方案,实现了机械结构方案的优化设计。依据设计方案,应用轻型铝合金材料完成了整体框架的机械结构设计与制作,其中部分零部件采用Solidworks建模,3D打印。控制部分采用凌阳SPCE061A控制板作为起重装置的主控板,L298N模块作为起重装置的驱动模块,通过改变控制电压,实现自锁电机的正反转,完成重物的起吊;运动部分采用迈特纳姆轮,可实现全向移动;三个吊臂高度按叠放三箱牛奶的高度设计,节约材料,方便控制。利用G+unSPIDE软件完成程序编写,实现了对三吊臂单独起升,同时起升,自动复位,全向移动等动作的控制。为应对起吊突发情况,制定了处置预案,优化了行进路径。实践证明,本设计实用性强、稳定性好、完成速度快,并且拥有较好的应用前景。

Design of a distributed power amplifier based on T-type matching networks

The impedance characteristics of distributed amplifiers are analyzed based on T-type matching networks, and a distributed power amplifier consisting of three gain cells is proposed. Non-uniform T-type matching networks are adopted to make the impedance of artificial transmission lines connected to the gate and drain change stage by stage gradually, which provides good impedance matching and improves the output power and efficiency. The measurement results show that the amplifier gives an average forward gain of 6 dB from 3 to 16. 5 GHz. In the desired band, the input return loss is typically less than - 9. 5 dB, and the output return loss is better than -8.5 dB. The output power at 1-dB gain compression point is from 3.6 to 10. 6 dBm in the band of 2 to 16 GHz while the power added efficiency （PAE） is from 2% to 12. 5% . The power consumption of the amplifier is 81 mW with a supply of 1.8 V, and the chip area is 0.91 mm × 0.45 mm.

Distributed amplifier of L-type network with 2-μm GaAs HBT process

The characteristic impedances of L-type and T-type networks are first investigated for a distributed amplifier design.The analysis shows that the L-type network has better frequency characteristics than the T-type one.A distribution amplifier based on the L-type network is implemented with the 2-μm GaAs HBT（heterojunction-bipolar transistor） process of WIN semiconductors.The measurement result presents excellent bandwidth performance and gives a gain of 5.5 dB with a gain flatness of ±1dB over a frequency range from 3 to 18 GHz.The return losses S11 and S22 are below-10dB in the designed frequency range.The output 1-dB compression point at 5 GHz is 13.3 dBm.The chip area is 0.95 mm2 and the power dissipation is 95 mW under a 3.5 V supply.

Novel hybrid optimal algorithm for broad-band Raman amplifier

A hybrid optimal algorithm, named the SAA-PA in brief, based on the simulated annealing algorithm （SAA） and the Powell algorithm （PA） is proposed. The proposed algorithm puts the random search strategy of the SAA into the PA, which can prevent optimizing courses from trapping in local optima. The SAA-PA can effectively solve multimodal optimization in the distributed multi-pump Raman amplifier （DMRA）. Optimal results show that, under the conditions of the on-off gain of 10 dB, the gain bandwidth of larger than 80 nm and the fiber length of 80 km, the gain ripple of less than 1.25 dB can be designed from the DMRA with only four backward pumps after the optimization of the proposed SAA-PA. Compared with the pure SAA, the SAA-PA can attain a lower gain ripple with the same number of pumps. Also, the relationship between the optimal signal bandwidth and the number of pumps can be simulated numerically with the SAA-PA.

Decomposition patterns of leaf litter of seven common canopy species in a subtropical forest： dynamics of mineral nutrients

Dynamical patterns of mineral elements during decomposition processes were investigated for seven common canopy species in a subtropical evergreen broad-leaved forest by means of litterbag technique over 2 years. The species studied are representative for the vegetation in the study area and differed significantly in chemical qualities of their litter. No significant relationships were found between decomposition rate （percentage dry mass remaining and decomposition constant k） and initial element cuncentrations.However, there were significant correlations betweeu the percentage of dry mass remaining and the mineral element concentrations in the remaining litter for most cases. The rank of the element mobility in decomposition process was as follows： Na = K 〉 Mg ≥ Ca 〉 N ≥ Mn ≥ Zn ≥ P 〉 Cu 〉〉 Al 〉〉 Fe. Concentrations of K and Na decreased in all species as decomposition proceeded. Calcium and Mg also decreased in concentrntion but with a temporal increase in the initial phase of decomposition, while the concentrations of other elements （Zn, Cu, AL and Fei increased for all species with exception of Mn which revealed a different pattern in different species. In most species, microelements （Cu, Al, and Fe） significantly increased in absolute amounts at the end of the litterbag incubation, which could be ascribed to a lange extent to the mechanism of abiotic fixation to humic substances rather than biological immobilization.

Three-dimensional analysis of natural convection in nanofluid-filled parallelogrammic enclosure opened from top and heated with square heater

A numerical study based on the finite volume method has been performed to study the three-dimension natural convection in a parallelogrammic top side opened cavity filled nanofluid with partially heated square at the bottom side.Results are obtained for different governing parameters such as nanoparticle concentration (φ) from 0 to 0.05,inclination angle of the back and front walls (α) from 5° to 75°,Rayleigh number from 10^3 to 10^5,and length of heater changer from 0.1 to 1.The main finding from the obtained result showed that the inclination angle and nanoparticle volume fraction affect the flow structure and enhance the heat transfer.

S-band gain flattened distributed fiber Raman amplifier with chirped fiber bragg grating filter

S-band gain flattened distributed fiber Raman amplifier with a bandwidth from 1 488 nm to 1 541 nm （53 nm in width） ,an averaged gain of 10 dB and a gain ripple of ±0.6 dB is obtained successfully, in which a single-wavelength high power fiber Raman laser with wavelength of 1 427.2 nm is used as the pump and the chirped fiber Bragg grating is used as the gain flattening filter. Besides,filter wavelength division multiplexer（FWDM） is used as the multi-signal multiplexer and 1 427 nm/1 505 nm coarse wavelength division multiplexer（OWDM） is used as the pump-signal coupler. The gain media are G652 fiber of 50 km in length and dispersion compensation fiber（DOF） of 5 km in length. Moreover, the location arrangements of different type of fibers and the effect caused by gain flattening filter as well as their solutions are discussed in detail. It is very significant to extend the range of optical fiber communication band and increase the capacity of fiber communication especially for ultra-long haul and ultra-high capacity communication system.

Short-term outcomes of laparoscopic total mesorectal excision compared to open surgery

AIM:To investigate the short-term outcome of laparoscopic total mesorectal excision(TME) in patients with mid and low rectal cancers.METHODS:A consecutive series of 138 patients with middle and low rectal cancer were randomly assigned to either the laparoscopic TME(LTME) group or the open TME(OTME) group between September 2008 and July 2011 at the Department of Colorectal Cancer of Shanghai Cancer Center,Fudan University and pathological data,as well as surgical technique were reviewed retrospectively.Short-term clinical and oncological outcome were compared in these two groups.Patients were followed in the outpatient clinic 2 wk after the surgery and then every 3 mo in the first year if no adjuvant chemoradiation was indicated.Statistical analysis was performed using SPSS 13.0 software.RESULTS:Sixty-seven patients were treated with LTME and 71 patients were treated with OTME(sex ratio 1.3:1vs 1.29:1,age 58.4 ± 13.6 years vs 59.6 ± 9.4 years,respectively).The resection was considered curative in all cases.The sphincter-preserving rate was 65.7%(44/67) vs 60.6%(43/71),P = 0.046;mean blood loss was 86.9 ± 37.6 mL vs 119.1 ± 32.7 mL,P = 0.018;postoperative analgesia was 2.1 ± 0.6 d vs 3.9 ± 1.8 d,P = 0.008;duration of urinary drainage was 4.7 ± 1.8 d vs 6.9 ± 3.4 d,P = 0.016,respectively.The conversion rate was 2.99%.The complication rate,circumferential margin involvement,distal margins and lymph node yield were similar for both procedures.No port site recurrence,anastomotic recurrence or mortality was observed during a median follow-up period of 21 mo(range:9-56 mo).CONCLUSION:Laparoscopic TME is safe and feasible,with an oncological adequacy comparable to the open approach.Further studies with more patients and longer follow-up are needed to confirm the present results.

Function Projective Synchronization of Fractional-Order Hyperchaotic System Based on Open-Plus-Closed-Looping

The purpose of this paper is to analyze the dynamic behavior of fractional-order four-order hyperchaotic Lii system, and use the Open-Plus-Closed-Looping （OPCL） coupling method to construct the system＇s corresponding response system, and then implement function projective synchronization （FPS） of fractional-order drive-response system with system parameters perturbation or not. Finally, the numerical simulations verify the effectiveness and robustness of this scheme.

Meta-analysis of laparoscopic vs open liver resection for hepatocellular carcinoma

AIM:To conduct a meta-analysis to determine the safety and efficacy of laparoscopic liver resection(LLR) and open liver resection(OLR) for hepatocellular carcinoma(HCC).METHODS:PubMed(Medline),EMBASE and Science Citation Index Expanded and Cochrane Central Register of Controlled Trials in the Cochrane Library were searched systematically to identify relevant comparative studies reporting outcomes for both LLR and OLR for HCC between January 1992 and February 2012.Two authors independently assessed the trials for inclusion and extracted the data.Meta-analysis was performed using Review Manager Version 5.0 software(The Cochrane Collaboration,Oxford,United Kingdom).Pooled odds ratios(OR) or weighted mean differences(WMD) with 95%CI were calculated using either fixed effects(Mantel-Haenszel method) or random effects models(DerSimonian and Laird method).Evaluated endpoints were operative outcomes(operation time,intraoperative blood loss,blood transfusion requirement),postoperative outcomes(liver failure,cirrhotic decompensation/ascites,bile leakage,postoperative bleeding,pulmonary complications,intraabdominal abscess,mortality,hospital stay and oncologic outcomes(positive resection margins and tumor recurrence).RESULTS:Fifteen eligible non-randomized studies were identified,out of which,9 high-quality studies involving 550 patients were included,with 234 patients in the LLR group and 316 patients in the OLR group.LLR was associated with significantly lower intraoperative blood loss,based on six studies with 333 patients [WMD:-129.48 mL;95%CI:-224.76-(-34.21) mL;P = 0.008].Seven studies involving 416 patients were included to assess blood transfusion requirement between the two groups.The LLR group had lower blood transfusion requirement(OR:0.49;95%CI:0.26-0.91;P = 0.02).While analyzing hospital stay,six studies with 333 patients were included.Patients in the LLR group were found to have shorter hospital stay [WMD:-3.19 d;95%CI:-4.09-(-2.28) d;P < 0.00001] than their OLR counterpart.Seven studies including 416 patients were pooled together to estimate the odds of developing postoperative ascites in the patient groups.The LLR group appeared to have a lower incidence of postoperative ascites(OR:0.32;95%CI:0.16-0.61;P = 0.0006) as compared with OLR patients.Similarly,fewer patients had liver failure in the LLR group than in the OLR group(OR:0.15;95%CI:0.02-0.95;P =0.04).However,no significant differences were found between the two approaches with regards to operation time [WMD:4.69 min;95%CI:-22.62-32 min;P = 0.74],bile leakage(OR:0.55;95%CI:0.10-3.12;P = 0.50),postoperative bleeding(OR:0.54;95%CI:0.20-1.45;P = 0.22),pulmonary complications(OR:0.43;95%CI:0.18-1.04;P = 0.06),intra-abdominal abscesses(OR:0.21;95%CI:0.01-4.53;P = 0.32),mortality(OR:0.46;95%CI:0.14-1.51;P = 0.20),presence of positive resection margins(OR:0.59;95%CI:0.21-1.62;P = 0.31) and tumor recurrence(OR:0.95;95%CI:0.62-1.46;P = 0.81).CONCLUSION:LLR appears to be a safe and feasible option for resection of HCC in selected patients based on current evidence.However,further appropriately designed randomized controlled trials should be undertaken to ascertain these findings.

A Study on Stochastic Resonance in Biased Subdiffusive Smoluchowski Systems within Linear Response Range

The method of matrix continued fraction is used to investigate stochastic resonance (SR) in the biasedsubdiffusive Smoluchowski system within linear response range.Numerical results of linear dynamic susceptibility andspectral amplification factor are presented and discussed in two-well potential and mono-well potential with differentsubdiffusion exponents.Following our observation,the introduction of a bias in the potential weakens the SR effect inthe subdiffusive system just as in the normal diffusive case.Our observation also discloses that the subdiffusion inhibitsthe low-frequency SR,but it enhances the high-frequency SR in the biased Smoluchowski system,which should reflect a'flattening' influence of the subdiffusion on the linear susceptibility.

Global Commercial Space Markets

Space is becoming more accessible than ever before. Falling satellite manufacturing and launch costs have opened the door to new players to enter the market, disrupting the status quo. HTS and constellations have entered the market and will lead to a lot more capacity at a lower price. But how this capacity will be optimally distributed remains a significant challenge. Earth Observation(EO) and Big Data are also areas of interest that are gaining grounds thanks to projects of 100 s if not 1,000 s of satellites that will have a lasting effect on manufacturing and launch markets.

The influence of discharge style on the separation of coarse coal slime by a hindered fluidized bed

Two kinds of liquid distributor, a central discharge or a peripheral discharge, were designed into a hindered fluid- ized bed separator. The beneficiation performance of the fluidized bed was investigated using 0.25-1.00 mm coarse coal slime and the two different distributors. The experimental results show that the heterogeneity of axial particle velocity in the radial direction of the bed can be reduced by a distributor that has a central discharge. The beneficiation performance for this dis- tributor is improved relative to the distributor with the peripheral discharge. This indicates that it is necessary to eliminate or suppress the core-annulus structure within a hindered fluidized bed. Increasing superficial water velocity causes the clean coal ash content, the railings ash content, and the combustible recovery to increase. Additionally, increasing the bed height decreases all of these three indexes. The optimum superficial water velocity and bed height for a 0.25-1.00 mm coal feed were deter- mined to be 3 mm/s and 800 mm, respectively. This work provides a foundation for the scale-up of the bed.

Low Noise Distributed Amplifiers Using a Novel Composite-Channel GaN HEMTs

Low noise distributed amplifiers （DAs） using the novel low noise composite-channel Al0.3 Ga0.7N/ml0.05 Ga0.95 N/ GaN HEMTs （CC-HEMTs） with 1μm-gate-length are designed and fabricated. Simulated and measured results of the DAs are characterized. The measured results show that the low noise DAs have input and output VSWR （voltage standing wave ratio） of less than 2.0,associated gain of more than 7.0dB and gain ripple of less than ldB in the frequency range from 2 to 10GHz. Noise figure of the DAs is less than 5dB in the frequency range from 2 to 6GHz,and less than 6.5dB in the frequency range from 2 to 10GHz. The measured results agree well with the simulated ones.

The Measurement of Carbon Emission Effect of Construction Land Changes in Anhui Province Based on the Extended LMDI Model

In the context of ＂two-wheel drive＂ development mode, China＇s construction land shows significant expansion characteristics. The carbon emission effect of construction land changes is an important factor for the increase of carbon emissions in the atmosphere. In this study, the drivers of carbon emissions in Anhui Province from 1997 to 2011 were quantitatively measured using the improved Kaya identity and Logarithmic Mean Divisia Index. The results show that： economic growth, expansion of construction land and changes in population density have incremental effects on carbon emissions. The average contribution rate of economic growth as the first driver is 266.32 percent. The construction land expansion is an important driving factor with annual mean carbon effect of 6.4057 million tons and annual mean contribution rate of 187.30 percent. But the change in population density has little impact on carbon emission driving. Energy structure changes and energy intensity reduction have inhibitory effects on carbon emissions, of which the annual mean contribution rate is -212.06 percent and -158.115 percent respectively. The targeted policy approaches of carbon emission reduction were put forward based on the decomposition of carbon emission factors, laying a scientific basis to rationally use the land for the Government, which is conducive to build an ecological province for Anhui and achieve the purpose of emission reduction, providing a reference for the research on carbon emission effect of changes in provincial-scale construction land.

Recent Progress in Distributed Optical Fiber Raman Photon Sensors at China Jiliang University

A brief review of recent progress in researches, productions and applications of full distributed fiber Raman photon sensors at China Jiliang University （CJLU） is presented. In order to improve the measurement distance, the accuracy, the space resolution, the ability of multi-parameter measurements, and the intelligence of full distributed fiber sensor systems, a new generation fiber sensor technology based on the optical fiber nonlinear scattering fusion principle is proposed. A series of new generation full distributed fiber sensors are investigated and designed, which consist of new generation ultra-long distance full distributed fiber Raman and Rayleigh scattering photon sensors integrated with a fiber Raman amplifier, auto-correction full distributed fiber Raman photon temperature sensors based on Raman correlation dual sources, full distributed fiber Raman photon temperature sensors based on a pulse coding source, full distributed fiber Raman photon temperature sensors using a fiber Raman wavelength shifter, a new type of Brillouin optical time domain analyzers （BOTDAs） integrated with a fiber Raman amplifier for replacing a fiber Brillouin amplifier, full distributed fiber Raman and Brillouin photon sensors integrated with a fiber Raman amplifier, and full distributed fiber Brillouin photon sensors integrated with a fiber Brillouin frequency shifter. The Internet of things is believed as one of candidates of the next technological revolution, which has driven hundreds of millions of class markets. Sensor networks are important components of the Internet of things. The full distributed optical fiber sensor network （Rayleigh, Raman, and Brillouin scattering） is a 3S （smart materials, smart structure, and smart skill） system, which is easy to construct smart fiber sensor networks. The distributed optical fiber sensor can be embedded in the power grids, railways, bridges, tunnels, roads, constructions, water supply systems, dams, oil and gas pipelines and other facilities, and can be integrated with wireless networks.

Particle inertia effect on sediment dispersion in turbulent open-channel flows

Particle inertia effect plays a significant role in sediment dispersion which has not been fully elucidated.In this paper,the profound effect of particle inertia on the sediment dispersion was analyzed.The theoretical expression for the drift velocity based on the two-phase mixture theory in turbulent open channels is firstly introduced.The influence of particle inertia on sediment dispersion was investigated through three different aspects including vertical dispersion,motion,and flux properties based on the drift velocity.Results show that the dispersion of suspended sediment in turbulent open-channel flows is affected by three major processes including turbulence of water sediment mixtures,particle random motion,and collisions among particles,of which the contributions of particle turbulence and collisions to the sediment dispersion are remarkable for particles of high inertia.With respect to the vertical mean velocity and sediment flux,it shows that the predictive results agree well with the measurements when the term of particle inertia is considered.As a result,particle inertia considerably affects the behavior of suspended sediment.In particular,the influence of inertia must be accounted for in circumstances of flows laden with high-inertia particles.