Open Space Ratio的译名、概念辨析与适用价值

Open Space Ratio(OSR)是《1961纽约市区划决议案》中居住环境控制的核心概念与重要指标,自1990年代始国内的许多学者引进这个概念,并倡导作为规划控制指标,因此也催生了中文术语"空地率"。本文系统梳理国内有关"OSR"和"空地率"研究的30余年学术文献,基于《1961纽约市区划决议案》的法律文本,对OSR的译名及其概念作出全面的阐释,澄清了OSR指标的意义、应用目的及其范围,辨析了OSR与中文术语"空地率"本质性的概念差异,建议将OSR指标引入控制性详细规划的居住环境控制,调整和完善我国控制性详细规划的指标控制体系。

Dissolution Kinetics of Calcined Ulexite in Ammonium Chloride Solutions at High Solid-to-Liquid Ratios

The dissolution kinetics of calcined ulexite in ammonium chloride solutions at high solid-to-liquid ratios were investigated. In the experiments, calcination temperature, solution concentration, reaction temperature, and pre-hydration were chosen as parameters. It was observed that the dissolution rate increased with increasing calcination temperature, solution concentration, and reaction temperature, whereas it was not affected by pre-hydration. Employing graphical and statistic methods, the dissolution rate, based on homogeneous reaction model, can be given as: (1-X(B2O3))-1-1= k(c(NH4Cl))1.982t. The activation energy for the dissolution of the ulexite sample calcined at 160 ℃ was found to be 84.04 kJ·mol-1.

PARAMETERS DETERMINATION METHOD OF PHASE-SPACE RECONSTRUCTION BASED ON DIFFERENTIAL ENTROPY RATIO AND RBF NEURAL NETWORK

Phase space reconstruction is the first step of recognizing the chaotic time series.On the basis of differential entropy ratio method,the embedding dimension opt m and time delay t are optimal for the state space reconstruction could be determined.But they are not the optimal parameters accepted for prediction.This study proposes an improved method based on the differential entropy ratio and Radial Basis Function(RBF)neural network to estimate the embedding dimension m and the time delay t,which have both optimal characteristics of the state space reconstruction and the prediction.Simulating experiments of Lorenz system and Doffing system show that the original phase space could be reconstructed from the time series effectively,and both the prediction accuracy and prediction length are improved greatly.

Experimental Study on Interference Effect of Three Risers Arranged in Tandem with Variable Spacing Ratios

Taking the three-riser group arranged in tandem as the research subject,an experimental study was carried out on the risers arranged in tandem.The purpose is to explore the sensitivity of the dynamic response of each riser to spacing ratio and reveal the physical mechanism of riser groups under the interference effect.The spacing ratios of the adj acent risers are 4.0,5.0,6.0,and 8.0.At the spacing between the risers of 4.0D,the strong feedback effect increases the cross-flow(CF) displacement amplitude of the upstream riser.The shielding effect is the key factor affecting the interference effect on the midstream and downstream risers.At low reduced velocities,the shielding area initially appears,the displacement amplitude of the midstream and downstream risers varies greatly,the vibration of the two risers is still dominated by the first-order mode,and the transition between adjacent vibration modes is restrained.The multi-frequency superposition phenomenon is very significant at high reduced velocities.The most sensitive interference spacing under the test conditions is obtained.Due to the separation of the incoming flow and the double shielding effect of the upstream and midstream risers,the regular vortex-induced vibration in the wake area of the downstream riser is broken,and the vibration in the two directions is weakened.In general,the interference effect is more significant for the CF vibration of the three-riser groups than the in-line(IL) vibration.

An Algorithm to Reduce Compression Ratio in Multimedia Applications

In recent years,it has been evident that internet is the most effective means of transmitting information in the form of documents,photographs,or videos around the world.The purpose of an image compression method is to encode a picture with fewer bits while retaining the decompressed image’s visual quality.During transmission,this massive data necessitates a lot of channel space.In order to overcome this problem,an effective visual compression approach is required to resize this large amount of data.This work is based on lossy image compression and is offered for static color images.The quantization procedure determines the compressed data quality characteristics.The images are converted from RGB to International Commission on Illumination CIE La^(∗)b^(∗);and YCbCr color spaces before being used.In the transform domain,the color planes are encoded using the proposed quantization matrix.To improve the efficiency and quality of the compressed image,the standard quantization matrix is updated with the respective image block.We used seven discrete orthogonal transforms,including five variations of the Complex Hadamard Transform,Discrete Fourier Transform and Discrete Cosine Transform,as well as thresholding,quantization,de-quantization and inverse discrete orthogonal transforms with CIE La^(∗)b^(∗);and YCbCr to RGB conversion.Peak to signal noise ratio,signal to noise ratio,picture similarity index and compression ratio are all used to assess the quality of compressed images.With the relevant transforms,the image size and bits per pixel are also explored.Using the(n,n)block of transform,adaptive scanning is used to acquire the best feasible compression ratio.Because of these characteristics,multimedia systems and services have a wide range of possible applications.

Phase-Space Areas of the Body Motion in the Solar System Deduced from the Bohr-Sommerfeld Atomic Theory and Approximate Invariance of Their Ratios for the Pairs of Planets and Satellites

Energy-time and momentum-position phase spaces defined by the electron orbits in the hydrogen-like atom exhibit special properties of equivalence. It is demonstrated that equivalence of the same kind can be obtained for the phase-space areas defined by the orbit pairs of planets, or satellites, which compose the solar system. In the choice of the examined areas it is useful to be guided by the Bohr-Sommerfeld atomic theory.

一种高效星载功率调节与配电单元设计与实现

文章结合深空探测供配电分系统任务特点,提出功率调节、配电、火工控制等多功能模块轻小型一体化设计的必要性。介绍了国外功率调节与配电单元的研究现状、国产功率调节与配电单元研制的意义,功率调节与配电单元组成及功能设计,并通过多母线融合设计、多路放电均流设计、单元集成化设计等关键技术,解决了深空探测器高可靠轻小型化功率调节与配电单元设计难题。在轨飞行结果表明:功率调节与配电单元功能正常,工作可靠,性能优良。功率调节与配电单元的国产化设计实现,可为其它航天器的设计提供参考和借鉴。

A Note on the Effect of Negative Poisson’s Ratio on the Deformation of a Poroelastic Half-Space by Surface Loads

The aim of this note is to study the effect of negative Poisson’s ratio on the quasi-static deformation of a poroelastic half-space with anisotropic permeability and compressible fluid and solid constituents by surface loads. Two particular cases considered are: two-dimensional normal strip loading and axisymmetric normal disc loading. It is found that a negative Poisson’s ratio makes the Mandel-Cryer effect more prominent. It also results in an increase in the magnitude of the surface settlement.

子宫内膜癌增强MRI定量参数变化与临床特征的关系及对预后的预测价值分析

目的 探究子宫内膜癌(EC)增强MRI定量参数变化与临床特征关系,分析其对预后的预测价值。方法 选取2019年3月~2022年3月本院收治的EC患者98例作为研究组,另选同期子宫内膜良性病变患者98例作为对照组。比较两组增强MRI定量参数[速率常数(K_(ep))、容量转移常数(K^(trans))、血管外细胞外间隙容积比(V_(e))]。比较研究组不同临床特征患者增强MRI定量参数,分析其与临床特征相关性。比较研究组不同预后患者增强MRI定量参数,分析其对预后的预测价值。结果 研究组K_(ep)、K^(trans)、V_(e)高于对照组(P<0.05);K_(ep)、K^(trans)、V_(e)病理分期、淋巴结转移、宫颈间质累及情况、子宫肌层浸润深度呈正相关,而与分化程度呈负相关(p<0.05)预后不良者K_(ep)、K^(trans)、V_(e)高于预后良好者,且与预后不良显著相关(P<0.05);K_(ep)、K^(trans)、V_(e)联合预测预后不良的AUC大于各参数独独预测(P<0.05)。结论 EC患者增强MRI定量参数K_(ep)、K^(trans)、V_(e)升高,且与临床特征、预后密切相关,联合检测各参数对预后不良具有一定预测价值。

宽孔距爆破模型试验及近场动力学计算研究

针对宽孔距爆破破岩技术中炮孔密集系数合理取值的问题,在总结国内外宽孔距爆破破岩机理的基础上,开展了炮孔密集系数为1.7、2.5、3.5、4.5的有机玻璃板室内爆破试验,并基于常规态型近场动力学原理,开发了爆破计算模块,对宽孔距爆破破岩中裂纹扩展过程、介质位移响应规律进行了研究。结果表明:临空面一侧的径向裂纹受到临空面反射拉伸应力波的作用,表现出向临空面拐角分叉的特征,并逐渐向临空面扩展,最后形成主裂纹组成漏斗形状。在最小抵抗线固定不变条件下,随着炮孔密集系数的增加,应力降低区逐渐增大,同排炮孔间的径向贯通裂隙消失,过大的炮孔密集系数也进一步造成前后排孔间贯通裂纹消失,最后导致单孔爆破的情况发生。位移计算结果进一步证实了上述规律,并且当炮孔密集系数较小时,前排炮孔留下的岩埂刚好被后排炮孔爆破破碎,随着炮孔密集系数的增大,后排孔爆破对前排炮孔所留下的岩埂破碎作用效果逐渐降低。建议实际工程中根据岩体力学性质、地质条件以及爆破目的适当调整密集系数来降低炸药单耗与大块率。

超声测量前额空间比联合无创产前DNA筛查早孕期胎儿染色体异常的临床价值

目的应用超声测量前额空间比(PFSR),探讨其联合无创产前DNA检测(NIPT)在早孕期胎儿染色体异常筛查中的临床应用价值。方法选取在我院接受早孕期羊水穿刺染色体核型检测的高危孕妇80例,均行产前超声检查及NIPT,以羊水穿刺染色体核型检测结果为金标准,比较超声测量PFSR、NIPT及两者联合应用筛查早孕期胎儿染色体异常的诊断效能。结果80例高危孕妇中,羊水穿刺染色体核型检测筛查胎儿染色体异常11例,其中21-三体综合征6例,18-三体综合征2例,13-三体综合征2例,Turner综合征1例。超声测量PFSR筛查早孕期胎儿染色体异常的灵敏度、特异度及准确率分别为63.64%、86.96%、83.75%;NIPT的灵敏度、特异度及准确率分别为72.73%、88.41%、86.25%;两者联合应用的灵敏度、特异度及准确率分别为90.91%、98.55%、97.50%,均高于单一方法,差异均有统计学意义(均P<0.05)。结论超声测量PFSR联合NIPT能提高筛查早孕期胎儿染色体异常的诊断效能,具有较好的临床应用价值。

高容积率小学建筑交通空间寻路认知研究

高容积率校园作为目前城市发展中重要的小学校园形式,用以缓解当下义务教育阶段学位的供需矛盾,从而进一步推动教育公平的实现。超高的建筑容积率作为这种校园类型的主要特征,会对学龄儿童的行为举止、心理情绪等造成巨大影响。选取红岭实验小学和坪山实验学校作为校园案例,并建构适合于学龄儿童的三维虚拟模型,通过寻路实验的方式获取儿童的寻路行为和空间认知的特征,总结提炼出影响儿童认知的交通空间要素,以期为同类高容积率小学交通空间的优化提供理论支持与参考。

亚临界雷诺数下串列双波浪锥柱绕流数值模拟

针对风力俘能结构布局问题,基于大涡模拟(LES)方法,在亚临界雷诺数下(Re=3900)研究有限长串列双波浪锥柱的升阻力特性及其流动结构随间距比的变化规律。结果表明:由于上游波浪锥柱的影响,下游波浪锥柱的脉动升力系数大幅增大,当间距比为3时,表面时均压力系数分布形式呈反向分布;随间距比增加,上游波浪锥柱尾流充分发展,并产生大量肋状涡撞击在下游波浪锥柱表面,下游波浪锥柱产生大的脉动升力,相较于单直圆柱提升约15.3倍,阻力系数降低约0.172。所得结果可为风力俘能结构布局提供有益参考。

城中村街巷空间绿视率分析与优化研究

绿视率作为人们对空间绿量的直观反映,也反映了道路与绿化的比例关系,所以绿视率和绿视率满意度能够以简洁的数据和评分反映街巷空间的绿化质量。以墨江县城中村街巷空间为例,采用现状调研、绿视率图像收集及计算、加上线下及网络问卷调查街巷空间满意度的方法进行研究,结果表明:(1)街巷空间平均绿视率均低于35%,居民满意度大部分评价为一般,现状景观质量较差,亟待提高。(2)经过对街巷空间绿视率及其满意度的深入评估,所得到的评价等级标准显示,在景观品质不佳的地区,公众对于绿视率的标准设定更高。(3)针对低绿视率现状提出空间优化、增加绿化、后期植物管理等优化策略,促进城中村人居环境的良好发展。

延长油田H区块剩余油分布规律及开发技术研究

为了更好的明确延长油田H区域剩余油的分布特征、开发潜力,以及有效的开发策略,运用油藏工程、动态监测、数值模拟相结合的方法,认识剩余油分布规律及主控因素,进一步揭示剩余油分布特征,为下一步注水开发提供理论基础。依据油藏工程及数值模拟精细描述成果,提出了能够提高采收率的合理注采比及地层压力保持水平,优选出中高含水阶段密井网下合理的开发技术,为研究区高效注水开发提供可靠的技术支撑。

不同种砂比和行距对机播荠菜农艺性状和产量的影响

为探索机播荠菜优质高效生产的最佳播量,更好地为荠菜种植机械化生产服务,采用双因素随机区组试验,共设置种砂(荠菜种子+黑金砂)混拌比1∶8、1∶11、1∶14和1∶17四个处理和行距14、21和28 cm 3个处理进行机器条播。结果表明,机播荠菜的农艺性状和产量随着种砂比的增加,表现出先增加后减少的趋势;行距与农艺性状和产量间相关性不显著。在12个种砂比和行距互作处理下,以A4B1(种砂比1∶17,行距14 cm)处理下的产量最高,每667 m^(2)产量可达2 230.84 kg。因此,推荐A4B1(种砂比1∶17,行距14 cm)为机播荠菜的最佳播量和行距。

提高湖羊圈养空间利用率的建模方案优化设计

为提高湖羊圈养的空间利用率,采用分期分批连续方式安排交配,根据交配期、怀孕期、哺乳期、休整期、育肥期等5个阶段的期长、容量、流转倍率等参数值,建立各期羊栏需求数的计算模型。针对养殖场现有的羊栏规格,经试算搜索得到其羊只的最佳流转速度,由此编制具体的生产方案,使得年化出栏羊只数量达到最大。继而针对5项不确定因素,构建参数重新选定的计算公式,并在合理范围内,调整哺乳期和空怀期时长,得到多种备选方案,再通过分层次计算比较各方案的期望损失,确定最优方案。

扩底桩竖向承载特性及群桩效应研究

为探明扩底群桩竖向承载特性,采用扩底桩筏结构,开展单桩(扩径比分别为1.5、2.0、2.5、3.0)和桩筏(扩径比为2)基础静载模型试验,分析其荷载传递规律,并建立桩间距为3.75、4.00、4.50、5.00倍桩直径时扩底桩筏基础有限元模型,研究桩间距对群桩效应影响。结果表明:扩底单桩和扩底桩筏结构荷载沉降曲线均为缓变型;扩底桩极限承载力随扩径比增大而逐渐增大,扩径比2.5~3.0时极限承载力增幅变缓,建议扩底桩扩径比取2.5~3.0;由于桩土共同沉降,桩间土压缩,桩土作用更充分,扩底桩筏基础中心桩侧摩阻力荷载分担比比扩底单桩增大了17.71%;群桩效应系数随桩间距增大而逐渐增大,桩间距为4.5~5.0倍桩直径时群桩效应系数增幅较小,群桩效应较弱,建议扩底桩筏基础桩间距取值不小于4.5倍桩直径。

Effects of Ratio of Row Spacing to Intrarow Spacing on Yield and Top Three Leaves of Super High-yielding Early and Late Rice

Using a split plot design, super high-yielding early rice ＆quot;Zhongjiazao 17＆quot;and ＆quot;Ganxin 203＆quot; and super high-yielding late rice ＆quot;Ganxin 688＆quot; and ＆quot;Wufengy-ouT025＆quot; were taken as materials with planting density the same at 312 000 hil s/hm2, to explore the effects of RS/IS （Ratio of row spacing to intrarow row spacing） on yield, top three leaves morphological features and its relationship of them in 2011 and 2012. The results showed that, whether early or late rice, biomass, accumula-tion and apparent utilizing rate of nitrogen were lower in RS/IS5.0 （40.0 cm ＆#215;8.0 cm） treatment, but yield of rice was higher in RS/IS2.0 （25.0 cm ＆#215;12.8 cm） treatment;grain numbers per spike of rice was more in RS/IS2.8 （30.0 cm＆#215;10.7 cm） treatment, and thousand-grain weight of rice was higher in RS/IS1.3 （20.0 cm＆#215;16.0 cm） treat-ment. For 4 varieties of early or late rice aforementioned, basal angle, opening an-gle and leaf area of 2nd leaf from top were larger in RS/IS5.0 treatment, and basal angle and opening angle were smal er in RS/IS2.0 treatment and leaf area smal er in RS/IS1.3 treatment.

采用多丝正比室读出的屏栅电离室能量分辨研究

搭建了一个基于多丝正比室读出的屏栅电离室探测器,使其保留屏栅电离室屏蔽特性的同时具备雪崩放大功能,通过在探测器内部对原初电离信号进行预放大,以提高信噪比,改善探测器的能量分辨率。利用241Am源详细测试了探测器在不同气压、沉积能量、阳极丝径时能量分辨率及增益随阳极电压的变化关系。探测器最佳能量分辨对应的工作电压与入射粒子在漂移区中沉积的能量有关,能量沉积越小,对应的最佳工作电压越高,探测器的增益越大。对于5.486 MeV的241Am α粒子源的能量分辨率可达1.45%。