Two‐Level Grids for Ray Tracing on GPUs

We investigate the use of two‐level nested grids as acceleration structure for ray tracing of dynamic scenes. We propose a massively parallel, sort‐based construction algorithm and show that the two‐level grid is one of the structures that is fastest to construct on modern graphics processors. The structure handles non‐uniform primitive distributions more robustly than the uniform grid and its traversal performance is comparable to those of other high quality acceleration structures used for dynamic scenes. We propose a cost model to determine the grid resolution and improve SIMD utilization during ray‐triangle intersection by employing a hybrid packetization strategy. The build times and ray traversal acceleration provide overall rendering performance superior to previous approaches for real time rendering of animated scenes on GPUs.     

Fully-adaptive algorithms for long-lived renaming

Long-lived renaming allows processes to repeatedly get distinct names from a small name space and release these names. This paper presents two long-lived renaming algorithms in which the name a process gets is bounded above by the number of processes currently occupying a name or performing one of these operations. The first algorithm is asynchronous, uses LL/SC objects, and has step complexity that is linear in the number of processes, c, currently getting or releasing a name. The second is synchronous, uses registers and counters, and has step complexity that is polylogarithmic in c. Both tolerate any number of process crashes.     

Precision,Local Search and Unimodal Functions

We investigate the effects of precision on the efficiency of various local search algorithms on 1-D unimodal functions. We present a (1+1)-EA with adaptive step size which finds the optimum in O(log n) steps, where n is the number of points used. We then consider binary (base-2) and reflected Gray code representations with single bit mutations. The standard binary method does not guarantee locating the optimum, whereas using the reflected Gray code does so in Θ((log n)²) steps. A(1+1)-EA with a fixed mutation probability distribution is then presented which also runs in O((log n)²). Moreover, a recent result shows that this is optimal (up to some constant scaling factor), in that there exist unimodal functions for which a lower bound of Ω((log n)²) holds regardless of the choice of mutation distribution. For continuous multimodal functions, the algorithm also locates the global optimum in O((log n)²). Finally, we show that it is not possible for a black box algorithm to efficiently optimise unimodal functions for two or more dimensions (in terms of the precision used).     

PIN OLEDs — Improved structures and materials to enhance device lifetime

Abstract— Currently, three issues are identified that decide upon the commercial success of organic light‐emitting diodes (OLEDs), both in display and lighting applications: power efficiency, lifetime, and price competitiveness. PIN OLEDs are widely seen as the preferred way to maximize power efficiency. Here, it is reported that this concept also delivers the world longest lifetimes. For a highly efficient deep‐red PIN OLED, a half‐lifetime of 25,000 hours for a starting brightness of 10,000 cd/m² and a minimal voltage increase over lifetime is reported. This value corresponds to more than 1 × 10⁶ hours at 1000 cd/m² using an exponent of n = 1.7, which was measured by driving the OLEDs at different starting luminances. Because there is no initial luminance drop, these PIN OLEDs also exhibit a very high 80% lifetime (>300,000 hours at 1000 cd/m²). New record lifetime values for blue and green will be reported as well. Additionally, further topics that have impact on the production yield and cost such as the newly developed air‐stable organic n‐doping material NDN‐26 and top‐emitting structures will be discussed.     

What is the optimal architecture for visual information routing?

Analyzing the design of networks for visual information routing is an underconstrained problem due to insufficient anatomical and physiological data. We propose here optimality criteria for the design of routing networks. For a very general architecture, we derive the number of routing layers and the fanout that minimize the required neural circuitry. The optimal fanout l is independent of network size, while the number k of layers scales logarithmically (with a prefactor below 1), with the number n of visual resolution units to be routed independently. The results are found to agree with data of the primate visual system.     

Statistische Beschreibung der Tropfengrößenverteilung bei stationären Zerstäubungsprozessen

The dispersion of spray drops within a two-phase-flow is signified by an deformable phase interface where material properties suddenly change. The process of atomisation could previously only be modelled for standard applications simultaneously coupled with substantial simulations. In this case the process of atomisation is not coupled to the direct numerical simulation (DNS) of the interaction between two liquids. The approach of disintegration is modelled by statistics, describing the probability of generating liquid droplets. Therefore consideration of potential time and length for an intact liquid core are supposed from standard applications [1, 2]. Using this way of describing atomisation is utilised in a CFD-Code and then compared with PDA-measurements to control the process capability of this implementation.

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Zusammenfassung  Zweiphasenströmungen zeichnen sich durch eine bewegliche und deformierbare Phasengrenze aus. An dieser Phasengrenze ändern sich die Stoffeigenschaften sprunghaft. Die Erfassung und Beschreibung dieser Grenzflächeneigenschaften ist sehr aufwendig, so dass die numerische Modellierung von Zerstäubungsprozessen bisher nur für exemplarische Einzelfälle eingesetzt wird. Bei dieser Simulation von Zerstäubungsprozessen ist ein hoher Rechenaufwand gegeben. Der Vorgang des Strahlzerfalls lässt sich, wie im Folgenden dargestellt, mittels Zerfallswahrscheinlichkeiten abbilden. Aerodynamische Grenzflächenbetrachtungen fließen bei dieser Betrachtungsweise nicht in das Modell ein. Bei der Verwendung von Zerfallswahrscheinlichkeiten werden Annahmen zu Länge und Zeit der intakten Strahllänge der flüssigen Phase getroffen, die sich aus ähnlichen technischen Fragestellungen in direkten numerischen Simulationen (DNS) ableiten lassen [1,2]. Durch Anwendung von statistisch erzeugten Tropfenspektren in einem Strömungscode und durch Messung mittels Phasen-Doppler-Anemometrie erfolgt die Überprüfung der Aussagefähigkeit des statistischen Modells.

     

Self-Consistent Quantum Mechanical Monte Carlo MOSFET Device Simulation

We have developed a self-consistent quantum mechanical Monte Carlo device simulator that takes electron transport in quantized states into consideration. Two-dimensional quantized states in MOSFET channels are constructed from one-dimensional solutions of the Schrödinger equation at different positions along the channel, and the Schrödinger and Poisson equations are solved self-consistently in terms of electron concentration and electrostatic potential distribution. The channel electron concentration, velocity and drain currents are calculated with the one particle Monte Carlo approach incorporating the intra-valley acoustic phonon and inter-valley phonon scattering mechanisms. This simulator was applied to a 70 nm n-MOSFET transistor, and we found that current mostly flows through the lowest subband and transport is quasi-ballistic near the source junction. To quantitatively estimate the performance of advanced devices, we have developed an inversion carrier transport simulator based on a full-band model. Our simulation method enables us to evaluate device characteristics and analyze the transport properties of ultra-small MOSFETs.     

欧洲和德国的钢铁工业的环保现状和发展(一)

欧洲钢铁工业的环境保护已经达到了很高的水平.20世纪60年代初,保护环境一般认为只是局限于限制工业对人们的影响.现在,尤其是在罗马协议(Club of Rome)的努力之下,环保的范围从节约资源延伸到整个自然环境的保护,而后产生了目前应用中的工业过程和产品生产周期.整体来说,保护环境的所有途径都被视为是未来平衡发展的先决条件. 欧盟环境保护技术的情况可以德国为例,更准确地说是杜伊斯堡的蒂森克虏伯钢厂(ThyssenKrupp Stahl AG),其粗钢产量约占德国总产量的35%. 钢铁工业环境保护的重点仍然是维护空气质量,在此目的下,进行除尘处理.由烟囱处取样获得目前的除尘水平来看,今后的除尘主要是控制粉尘扩散和减少细小微粒的排放. 钢铁工业环境保护的关键策略就是循环利用,它能起到与环境协调一致的作用,能够解决相关工艺中需要的大量的原料问题.德国的蒂森克虏伯钢厂(ThyssenKrupp Stahl AG)现在炉渣的综合回收率水平已接近95%,其中冶金渣的回收利用率尤为突出.在德国,高炉渣利用率达到了100%,同时炼钢渣的利用率也超过了90%,每吨粗钢的耗水量也控制在100 m3的范围内.大量的努力不仅保证了有效的回收和再生利用工序,而且冷却水的利用也保证了新水的补充率降低到每吨粗钢15m3左右. 污染控制除与主要环境即空气、水和土壤有关外,已扩展到回收过程再利用的水平,更多地重点渐渐地放到相关产品的环境保护.产品和原料却日益受到生产商和消费者的重点检验,有点与环境协调性标准相反.组织机构的环境保护手段包括环境管理系统的认可、生态平衡、政府部门的自愿协议以及提高公众的信息、教育水平. 欧洲的钢铁工业,当然也包括德国,都已经意识到环境保护的重要性同工业研究与开发的重要性处于同等地位.一个典型的例子就是超薄板汽车用钢项目,这个与产品相关的研究引入了35家合作厂商共同研究一个比目前传统的汽车车身更结实、更轻的项目.欧洲钢铁厂家的联合合作已经成功研究出应用于烧结厂的减少二恶英(dioxin)排放物的吸收工艺.用褐煤焦尘作为吸附剂,已能够平均减少排放物大约70%.很可能2003年在杜伊斯堡的ThyssenKrupp Stahl AG将被授权建全世界最先进的焦化厂.在这个项目过程中研究出的主要部分成果,例如低尘低烟煤湿熄法和减少PAH排放物的单室压力控制系统,会恰当地应用于新的工厂.另一个主要进步是ThyssenKrupp Stahl AG研制的Hamborn OxiCup竖炉,它有湿法冶炼和排除含铁残渣的功能.此技术预计成为回收利用铁水和钢产品中产生的粉尘和泥浆这一难题的解决方案. 德国的局势尤其显示出环境法规的落实正开始对经济发展和劳动力市场起到不利影响.盛行的经济技术条件需要合法的体制治理环境保护的合理化.将来任何进一步的措施都要考虑这一事实,既要获得可持续发展,又要考虑到经济发展和社会需求.