On the Performance of Ozone Generators Working with Dielectric Barrier Discharges

The parameters, which determine the performance of ozone generators, are efficiency and maximum ozone concentration. The efficiency from oxygen has been found to be nearly independent on the kind of barrier discharge arrangement (volume, surface, coplanar), while the ozone concentration saturation level depends on the specific design of the generator. These phenomena are explained with features of the discharge process and the properties of chemical reactions, respectively. The importance of a limit in the energy density of the discharge is highlighted.     

Matching Polyhedral Terrains Using Overlays of Envelopes

For a collection $\F$ of $d$-variate piecewise linear functions of overall combinatorial complexity $n$, the lower envelope $\E(\F)$ of $\F$ is the pointwise minimum of these functions. The minimization diagram $\M(\F)$ is the subdivision of $\reals^d$ obtained by vertically (i.e., in direction $x_{d+1}$) projecting $\E(\F)$. The overlay $\O(\F,\G)$ of two such subdivisions $\M(\F)$ and $\M(\G)$ is their superposition. We extend and improve the analysis of de Berg et al. \cite{bgh-vdt3s-96} by showing that the combinatorial complexity of $\O(\F,\G)$ is $\Omega(n^d \alpha^{2}(n))$ and $O(n^{d+\eps})$ for any $\eps>0$ when $d \ge 2$, and $O(n^2 \alpha(n) \log n)$ when $d=2$. We also describe an algorithm that constructs $\O(\F,\G)$ in this time. We apply these results to obtain efficient general solutions to the problem of matching two polyhedral terrains in higher dimensions under translation. That is, given two piecewise linear terrains of combinatorial complexity $n$ in $\reals^{d+1}$, we wish to find a translation of the first terrain that minimizes its distance to the second, according to some distance measure. For the perpendicular distance measure, which we adopt from functional analysis since it is natural for measuring the similarity of terrains, we present a matching algorithm that runs in time $O(n^{2d+\eps})$ for any $\eps>0$. Sharper running time bounds are shown for $d \le 2$. For the directed and undirected \Hd\ distance measures, we present a matching algorithm that runs in time $O(n^{d^2+d+\eps})$ for any $\eps>0$.     

Organizational arrangements for MIS units

Decisions on organizational arrangements for MIS units comprise location in the organization, rank of responsible executive, organization of MIS implementators, degree of centralization, the user interface, the study group, the steering committee, the data base administrator, the corporate computer staff, and external assistance. Based on a wide-ranging survey of papers in the field of MIS, the authors have formulated guidelines which derive from the impact of organizational decisions on the success or failure or MIS and MIS projects.     

Dynamic half-space range reporting and its applications

We consider the half-space range-reporting problem: Given a setS ofn points in ^d, preprocess it into a data structure, so that, given a query half-space , allk points ofS can be reported efficiently. We extend previously known static solutions to dynamic ones, supporting insertions and deletions of points ofS. For a given parameterm,n m n ^d/2 and an arbitrarily small positive constant , we achieveO(m ¹⁺) space and preprocessing time, O((n/m ^d/2 logn+k) query time, and O(m¹⁺n) amortized update time (d 3). We present, among others, the following applications: an O(n¹⁺)-time algorithm for computing convex layers in ³, and an output sensitive algorithm for computing a level in an arrangements of planes in ³, whose time complexity is O((b+n) n, whereb is the size of the level.Work by the first author has been supported by National Science Foundation Grant CCR-91-06514. A preliminary version of this paper appeared in Agarwalet al. [2], which also contains the results of [20] on dynamic bichromatic closest pair and minimum spanning trees.     

调整水资源费征收标准促进引黄入晋工程太原供水区水资源优化配置

万家寨引黄一期工程已具备向太原供水区供水3.2亿m3的能力。但由于太原供水区水资源尚未达到优化配置,一方面工程能力大量闲置,另一方面仍大量超采地下水,造成环境破坏。文中提出进一步调整地下水水资源费征收标准,利用经济杠杆促进引黄入晋工程太原供水区水资源优化配置。     

用ASP开发基于B/S模式的高校监考安排系统

通过对高校管理水平的分析,提出用ASP开发基于B/S模式的高校监考安排系统,并对系统的设计思想加以详细阐述。该系统能够对成本、人员、任务等环节的信息数据在Internet上进行处理,对信息数据进行实时控制和综合分析处理。高校监考安排系统对提高高校管理水平具有重要的作用。     

Improved Algorithms for Uniform Partitions of Points

Abstract. We consider the following one- and two-dimensional bucketing problems: Given a set S of n points in \reals ¹ or \reals ² and a positive integer b , distribute the points of S into b equal-size buckets so that the maximum number of points in a bucket is minimized. Suppose at most (n/b) + Δ points lie in each bucket in an optimal solution. We present algorithms whose time complexities depend on b and Δ . No prior knowledge of Δ is necessary for our algorithms. For the one-dimensional problem, we give a deterministic algorithm that achieves a running time of O(b ⁴ (Δ ² +log n) + n) . For the two-dimensional problem, we present a Monte Carlo algorithm that runs in subquadratic time for small values of b and Δ . The previous algorithms, by Asano and Tokuyama [1], searched the entire parameterized space and required Ω ( n ² ) time in the worst case even for constant values of b and Δ . We also present a subquadratic algorithm for the special case of the two-dimensional problem when b=2 .     

建筑美术素描教学浅议

建筑美术素描教学应加强对造型思维想象力和创造力的培养。教学不同层次划分使我们的教学理论具体化、系统化,有计划有针对性地进行教学是确保我们的教育思路和目标得以实现的保证。     

The Housing Consequences of Living Arrangement Choices in Young Adulthood

This paper documents the consequences of the first living arrangements of young adults after leaving the parental home (without a partner, cohabiting, or married) for their housing situation, whether they rent independently, share accommodation, or own their own homes, both immediately after leaving home and in the first eight years after leaving. Data are analysed from two retrospective life-course surveys conducted in the Netherlands in the 1990s, using multinomial logistic regression models. The paper finds a strong influence of the timing and pathway of leaving on the housing situation immediately after leaving: those nest-leavers who make stronger commitments in their household careers (by cohabiting, or by marrying) are more likely to own a home and less likely to share. Although through the years after leaving home this influence decreases, it remains discernible and significant even eight years after leaving. This is remarkable, given the fluidity of the housing careers of nest-leavers.     

Productivity and Efficiency of Ozone Synthesis in Coplanar Discharge Arrangements

In order determine the potential of coplanar discharge arrangements with short electrode distances for the production of ozone, a numerical model of the discharge behavior has been developed. The temporal and spatial distributions of the discharge parameters e.g. those of the field strength, the densities of the charged particles in the gas region and on the dielectric surface and that of the energy release reveal that the ozone production results from the electron phase of the discharge. Quantitative data of the productivity and efficiency of the ozone yield in a certain system are presented, which are in agreement with experimental results.