徐州地区冬季日光温室内气温模拟研究

根据徐州地区日光温室小气候观测资料,分析了冬季日光温室内的气温与相对湿度、太阳辐射度及土温之间的相关性,选相关系数较大的因子作为建模因子,并据此模拟温室内气温和分析日光温室气温的变化,以此运用于指导生产,提高经济效益。     

基于可变模糊集的海洋水质环境综合评价模型—以青岛疏浚物海洋倾倒区为例

传统的水质评价方法,往往将评价标准或参考标准处理成点的形式,难以反映水质分级的区间特征,本文探索将可变模糊数学模型应用到海洋水质环境综合评价中,同时将熵权理论与主观权重相结合,以综合权重作为基础构建基于可变模糊集的海洋水质环境评价模型,并将其应用于青岛倾倒区海水水质综合评价中,实例研究证明,该模型能够很好地对海洋水质环境综合情况进行准确评价,该模型通过变化模型参数(α与p,4个模型,1个线性,3个非线性),4种模型相互检验,将稳定结果作为最后评价结果,评价结果更为可信,同时,该模型能够通过级别特征值精确区分各海洋水质采样点的水质优劣,对各采样点的水质级别有更准确的定位,为改进和完善海洋环境评价研究领域提供了新的思路和方法.     

基于Bezier曲线的参数化设计方法

为实现基于曲线的参数化设计方法,给出了一个适合于参数化设计的Ｂezier曲线表示形式,提出了在几种约束条件下约束的满足方法,涉及曲线的求导、求交及曲线的拼拼和过渡线的求取方法,并给出了Ｂezier曲线等距线的一种多项式逼近算法,运用上述方法给出了一个Ｂezier线参数化设计的实例。     

Building on quicksand: the foundations of the Eastern Scheldt barrier

The long and successful experience of the Dutch in recovering land from the sea and protecting it from inundation needs no emphasis. Even their ingenuity in civil engineering has been challenged, however, in the design and construction of a storm-surge barrier across the Eastern Scheldt, for it has virtually to be built on quicksand. This article describes the way in which the problem has been solved by laying huge prefabricated filter mattresses on the seabed to provide a secure foundation against the assaults of the highest tides.     

Closed plane curves described by finite and infinite sums of rotating vectors

A large group of closed plane curves may be classified as roulettes, including epicycloids, hypocycloids, and related epitrochoids and hypotrochoids. The equation for the roulette in complex polar form shows that any roulette may be described by the vector sum of two vectors of specified constant magnitudes rotating with constant angular velocities. Methods for plotting, and for electronic display of roulettes are described. An equation is derived for a roulette approximation for an N-sided regular polygon. In particular, an application to two-dimensional potential theory is described and illustrated by consideration of the roulette approximation for a square as an equipotential curve, with derivation of equations for equipotential curves in the field surrounding the square. General equations are derived for given closed plane curves with points whose x and y coordinates may separately be expanded in Fourier series as functions of the polar angle, assuming these expansions are valid. It is shown that, in general, a closed plane curve may be considered as being described by an infinite sum of vectors, each rotating in a circle. Simplifying effects of symmetry about a polar axis and/or about the origin are discussed, and methods for harmonic analysis of a given closed plane curve with aid of an electronic calculator are described.     

Improving Information Retrieval Performance on OCRed Text in the Absence of Clean Text Ground Truth

OCR errors in text harm information retrieval performance. Much research has been reported on modelling and correction of Optical Character Recognition (OCR) errors. Most of the prior work employ language dependent resources or training texts in studying the nature of errors. However, not much research has been reported that focuses on improving retrieval performance from erroneous text in the absence of training data. We propose a novel approach for detecting OCR errors and improving retrieval performance from the erroneous corpus in a situation where training samples are not available to model errors. In this paper we propose a method that automatically identifies erroneous term variants in the noisy corpus, which are used for query expansion, in the absence of clean text. We employ an effective combination of contextual information and string matching techniques. Our proposed approach automatically identifies the erroneous variants of query terms and consequently leads to improvement in retrieval performance through query expansion. Our proposed approach does not use any training data or any language specific resources like thesaurus for identification of error variants. It also does not expend any knowledge about the language except that the word delimiter is blank space. We have tested our approach on erroneous Bangla (Bengali in English) and Hindi FIRE collections, and also on TREC Legal IIT CDIP and TREC 5 Confusion track English corpora. Our proposed approach has achieved statistically significant improvements over the state-of-the-art baselines on most of the datasets.     

PD模式下IQ信号被干扰的一种解决方法

PD模式雷达,IQ信号被干扰,引起相位变化,导致画面虚警增加,速度解算不准确,目标检测能力下降的问题,采集数据仿真分析,提出一种解决方法,进而工程实现,得到比较好的效果。     

21世纪以来诺贝尔科学奖成果性质的技术科学趋向

从21世纪以来诺贝尔科学奖得主的专利数据出发,依据钱学森的技术科学理论和科学技术体系层次结构思想,对诺奖成果的科学性质进行判断和分类。诺奖数据显示,近15年来,物理学领域呈现出基础科学和技术科学平分秋色的局面,而化学、生理学或医学领域明显地出现了趋向技术科学一边倒的局面。这意味着,仅从基础科学层次出发不足以实现接近诺奖和提升科技实力的宏伟目标,必须重视技术科学在建设科技强国过程中的战略意义。     

Improved delay-range-dependent robust stability criteria for a class of Lur’e systems with sector-bounded nonlinearity

In this paper, the problem of delay-dependent stability of a class of uncertain Lur’e systems of neutral type with interval time-varying state delay and sector-bounded nonlinearity has been considered based on Lyapunov–Krasovskii functional approach. By constructing a candidate Lyapunov–Krasovskii (LK) functional, less conservative robust stability criteria are proposed in terms of linear matrix inequalities (LMIs). The reduction in conservatism of the proposed stability criteria over recently reported results is attributed to the candidate LK functional used in the delay-dependent stability analysis, and to the tighter bounding of the time-derivative of the functional without neglecting any useful terms using minimal number of slack matrix variables. The proposed analysis, subsequently, yields a stability condition in convex LMI framework, and is solved non-conservatively at boundary conditions using standard numerical packages. The effectiveness of the proposed stability criterion is demonstrated through standard numerical examples.     

以工程教育专业认证为导向的化工专业改革探析

工程教育专业认证是工程教育质量保障体系的重要组成部分,实施工程教育专业认证是我国工程教育与国际接轨的必然选择。文章阐述了化学工程与工艺专业实行专业认证的重要意义。通过解读化学工程与工艺专业认证标准,对照当下化学化工高等教育办学过程中的一些问题,提出了化工专业教学的改革措施。从调整培养计划,优化课程结构,加强实践环节,提高教师的工程实践水平,增强学生的团队精神训练,完善毕业生的调查与跟踪机制等诸多方面论证了以工程教育专业认证为导向的化工专业改革思路。     

提高园林施工管理水平的几点建议

在园林绿化迅猛普及的今天,园林工程面临着更高的质量要求。陈旧的技术规范标准、落后的设备保证和常规的检验手段无法满足工程质量更高的潜在需要。文章提出一些新的建议,从多方位提高园林施工管理的水平,促进园林工程越做越好、越做越精。     

Model-based deep reinforcement learning for data-driven motion control of an under-actuated unmanned surface vehicle: Path following and trajectory tracking

Unmanned surface vehicles (USVs) are a promising marine robotic platform for numerous potential applications in ocean space due to their small size, low cost, and high autonomy. Modelling and control of USVs is a challenging task due to their intrinsic nonlinearities, strong couplings, high uncertainty, under-actuation, and multiple constraints. Well designed motion controllers may not be effective when exposed in the complex and dynamic sea environment. The paper presents a fully data-driven learning-based motion control method for an USV based on model-based deep reinforcement learning. Specifically, we first train a data-driven prediction model based on a deep network for the USV by using recorded input and output data. Based on the learned prediction model, model predictive motion controllers are presented for achieving trajectory tracking and path following tasks. It is shown that after learning with random data collected from the USV, the proposed data-driven motion controller is able to follow trajectories or parameterized paths accurately with excellent sample efficiency. Simulation results are given to illustrate the proposed deep reinforcement learning scheme for fully data-driven motion control without any a priori model information of the USV.     

我国海岸带湿地生态系统退化成因及其对策

由于全球气候变化与人类活动影响,我国海岸带湿地已面临着严重的退化风险。文章通过对海岸带湿地退化多重因素,如海岸带围垦、城市化发展、海岸养殖、外来物种入侵、海岸侵蚀、环境污染及海平面上升等进行分析,探讨并提出适应我国海岸带地区发展特征的"与自然共建"湿地修复、湿地生态系统自然资本有效评估及补偿、湿地综合监测等应对策略,为实现我国海岸带地区科学和合理的可持续发展提供决策依据。     

Hodograph transformation

Mapping of curves from the physical to the hodograph plane, when the Jacobian vanishes along a curve is discussed in detail here. A certain quadratic expression occuring in the equations has been identified as the important factor in the transformation. The nature of the transformation depends on whether the roots are complex or real distinct and so on. A geometrical representation of the referred quadratic expression is also presented, resulting in a better understanding of the transformation technique.     

基于ISO9000的固井质量体系建立与运行探讨

立足TQM理论和ISO9000标准的应用、创新与延伸,以大质量观念为指导,全员参与,运用过程方法和系统化的方法,识别和策划质量管理体系的过程,建立和运行科学的固井施工质量管理模式,确定过程运行和控制准则,强化内部管理,使质量管理科学化、程序化,追求零缺陷,达到提升固井施工工程质量和效率增值,增强固井施工企业的竞争优势。     

标准曲线拟合方法的改进

以丁二酮肟分光光度法测定水中镍的标准曲线为例,运用最小二乘法对标准曲线进行拟合,得出,。因x即吸光度趋于零时,镍含量y可能为负数,不符合客观实际,所以对其标准曲线的拟合进行了改进,对如何改进进行了探讨。     

海水密度对海面高变化的影响

基于TOPEX/Poseidon卫星测高资料,采用WOA98海水温度及盐度模型,计算了多层海水密度变化引起的海面高变化。结果表明,海水密度变化是引起季节性海面高变化的重要因素。另外,在考虑和不考虑海水密度变化的情况下,估算了海面异常引起上海GPS测站位移和地球重力场位系数J2 的变化。表明,在研究许多地球动力学问题时,扣除海水密度变化引起的海面高变化至关重要     

中国县域地面坡谱分级及其与人口分布的关系

针对平均坡度指标难以稳健描述地面坡谱特征的问题,提出一种基于频率累加分位归并的坡谱分级方法。作为验证,运用数字高程模型数据将全国县域分为5个坡级,借助2000年和2020年人口普查数据分析了坡级与人口分布的关系。结果发现：（1）所提出的分级方法包含频率累加曲线的构建、基于分位数的参考曲线生成、基于相似度的类型归并3个关键步骤,由此得到的全国县域坡级划分方案具备稳健坡度梯度性、宏观空间连片性以及清晰地学含义。（2）全国县域人口数量总体保持随坡级升高而波动式缩小的特征,且二者间呈现明显的线性负相关关系,线性拟合R2从2000年的0.761上升到了2020年的0.845,20年间人口总数变化量与坡级的线性拟合R2达0.963;人口密度的极端值对其自身的坡级分布有较大影响,当剔除人口密度小于20人/km2和大于2000人/km2的区域后,两个分析年份全国县域人口密度均稳健保持着随坡级升高而线性减小（R2> 0.985）。本文为稳健表达如坡度等环境梯度提供了一种新的可行分级方法,并深化了对中国县域人口分布与坡度关系的认识。     

工业用水库兹涅茨曲线分析

水资源稀缺是21世纪社会经济增长乃至人类生存所面临的重大挑战之一,探索工业水资源利用情况是进一步研究工业水资源节约利用的基础。基于2000-2013年中国31个省份的面板数据,在单位根检验以及协整检验的基础上,对全国以及东、中、西部地区工业水资源利用与工业经济增长之间的关系进行实证检验,结果显示：东部地区二者关系曲线呈现为倒“U”型,且拐点出现在人均工业增加值28 612.150元/人时;中部地区二者关系曲线呈现为“N”型,且拐点分别出现在人均工业增加值15 546.048元/人和35 733.952元/人时;而全国和西部地区二者近似地满足单调递增的关系。经分析,技术创新、结构调整是使工业用水倒“U”型库兹涅茨曲线拐点出现的技术层面的原因,水价提升、水权交易则是其经济激励措施。最后提出应积极进行技术创新、推进产业结构调整以及工业内部行业结构调整,同时适当提升工业用水价格、完善水权交易制度以最终实现工业水资源节约等政策建议。     

现代生物技术制药研究及展望

伴随着现代生物技术水平的迅速提升,药物在预防、诊断、治疗各种疾病方面有了很大改善。文章搜集了大量与现代生物制药技术方面的文献资料,并在基础上阐述基因工程制药、细胞工程制药及生化工程制药等技术内容,分析现阶段我国生物制药技术中存在的问题,就未来发展方向提出具有针对性的优化策略。