“BASS 300 PARACOM”: a “model” underwaterparametric communication system

Parametric transduction offers valuable advantages for underwater acoustic communications. Perhaps the most significant benefit is the fact that high directivity is achieved by means of a physically small transmit transducer. This feature may, ultimately, be employed to permit long-range, low-frequency communication using a compact source. The high directivity is desirable to combat multipath propagation and to achieve data communications in water which is shallow by comparison with range. A real-time, high data-rate “model” differential phase shift keying (DPSK) communication system has been constructed and demonstrated. This system uses parametric transduction, with a 300-kHz primary frequency and a 50-kHz secondary frequency. Experimental results show that the system can be employed to combat multipath propagation in shallow water and can achieve high data-rate text and color image transmission at 10 and 20 kb s^-1 for 2-DPSK and 4-DPSK, respectively, through a transmission bandwidth of 10 kHz. The “model” system was developed to confirm performance predictions for a future, operational long-range link employing a 50-kHz primary frequency and a 5-kHz secondary frequency     

OH masers in W 33A

This paper presents observations of OH maser lines of W 33A for the transitions ²Π_3/2, J = 3/2, F = 1 → 1 and F = 2 → 2. Two models, a thin tube and a sphere, were used for modelling the masing region and a molecular hydrogen density of about 10⁷ cm⁻³ was obtained. To give a maser photon emission of the order of 10⁴⁶ s⁻¹, both models require a pump rate of 1 OH cm⁻³s⁻¹, while the sphere model requires a higher pump efficiency.     

基于GPS掩星技术反演大气参数模型的优化

准确掌握地球大气中的水气分布，了解水气变化趋势对天气现象、全球气候变化、数值预报具有理论研究及实用价值。以无线电掩星技术为基础，利用掩星数据反演大气参数剖面。对原反演模型的不足进行了论证，并给出了反演个例。详细地论述了通过引入MM5先验温度T再通过线性迭代的方法反演对流层下部水汽廓线原理，给出了优化后模型反演个例。并对模型优化后反演廓线中存在的问题进行了分析，提出了下一步优化方向。     

Soil respiration in tropical seasonal rain forest in Xishuangbanna, SW China

With the static opaque chamber and gas chromatography technique, from January 2003 to January 2004 soil respiration was investigated in a tropical seasonal rain forest in Xishuangbanna, SW China. In this study three treatments were applied, each with three replicates: A (bare soil), B (soil+litter), and C (soil+litter+seedling). The results showed that soil respiration varied seasonally, low from December 2003 to February 2004, and high from June to July 2004. The annual average values of CO2 efflux from soil respiration differed among the treatments at 1% level, with the rank of C (14642 mgCO2· m-2. h-1)＞B (12807 mgCO2· m-2. h-1)＞A (9532 mgCO2· m-2. h-1). Diurnal variation in soil respiration was not apparent due to little diurnal temperate change in Xishuangbanna. There was a parabola relationship between soil respiration and soil moisture at 1% level. Soil respiration rates were higher when soil moisture ranged from 35% to 45%. There was an exponential relationship between soil respiration and soil temperature (at a depth of 5cm in mineral soil) at 1% level. The calculated Q1o values in this study,ranging from 2.03 to 2.36, were very near to those of tropical soil reported. The CO2 efflux in 2003was 5.34 kgCO2· m-2. a-1 from soil plus litter plus seedling, of them 3.48 kgCO2· m-2. a-1 from soil (accounting for 62.5%), 1.19 kgCO2· m-2. a-1 from litter (22.3%) and 0.67 kgCO2·m-2. a-1 from seedling (12.5%).     

长江口斜压诊断模式三维流场数值模拟

建立了σ坐标系下长江口斜压诊断模式三维流场数学模型,采用k-kl二方程紊流闭合模型求解垂向涡粘系数,计算域内恒定、非均匀盐度场反映了计算域密度斜压效应。验证结果表明,斜压诊断模式的模拟成果较切合实际。模型成功复演了长江口水域由往复流向旋转流过渡的流场特性;潮波从四条汊道传入后在分汊口附近相遇形成多个会潮点,其位置随着径流的大小、潮汐的强弱、汊道的形态等因素而变化。     

一种新型降水预报评分方法

在目前已有的降水评分办法的基础上，对原有办法存在的弊端进行了有效的改进，使得降水的预报评估与预报服务业务结合更紧密，也更贴近公众的感受。主要介绍了新方法的基本思路、关键技术、实现方法等。评分系统已投入业务运行，成为考核预报员业务水平的重要依据。     

省区碳经济分析的CGE模型及其应用——以河南省为例

作为一种最划算的减排措施,碳税已在个别国家开始实施。编制河南省社会核算矩阵表（SAM）及其他区域SAM,构建了一个30部门的双区域的可计算一般均衡模型（CGE）,分析对能源产业（煤炭开采和洗选业、石油和天然气开采业、石油炼焦核燃料加工业和燃气生产和供应业）分别征收不同价格的碳税后,河南省经济及人民生活水平的变化情况。并考虑不同类型的碳税返还情景带来的居民和企业效益,以期为通用的双区域CGE模型提供依据。模拟结果显示：碳税的征收可以有效减少CO₂的排放;导致河南省增加值的下降;能源产业中煤炭开采和洗选业的国内价格受负面影响最大;其他行业中农林牧渔业受到的负面影响较大。农村居民比城市居民对碳税政策的反应更加敏感,且碳税对农村居民带来的影响为负面的。对比分析的结果表明,碳税返还给农村居民是一个合适的选择,能够使得农村居民、城镇居民和企业的利益都得到保障。     

论中国名山的分类

名山分类是山地旅游资源开发的重要理论之一．按成因、属性和功能等不同标准,将中国名山分成地质、气候、历史、文化、政治、军事、揽胜、探险、科考、健身等17个主要类型．     

东北三省城乡收入差距空间格局及其分异机制研究

借助多元逐步线性回归、GWR等模型方法,探讨1990年以来东北三省城乡收入差距空间格局、类型特征及其分异机制,最后提出城乡统筹可持续发展建议。结果表明： 1990年以来,东北三省城乡居民收入水平大幅提高,但大部分地区城镇居民可支配收入水平仍低于全国平均水平;城乡收入差距整体有所拉大,呈现出“中间高、两端低”的空间特征。 城乡收入差距空间分布格局受经济发展水平、工业拉动效应、服务业带动力和交通通达程度影响,其中经济发展水平对城乡收入差距由早期的正向拉大作用为主,逐步演变为负向抑制效应。 据此提出对策建议：深化改革开放,加快国有企业改革步伐,优化区域产业结构,提高服务业发展水平和比重,激发市场活力,破解制约区域经济发展的各种障碍;加快实施乡村振兴战略,促进乡村资源开发,开辟致富增收新路径。