Zipper: A compact connectivity data structure for triangle meshes

We propose Zipper, a compact representation of incidence and adjacency for manifold triangle meshes with fixed connectivity. Zipper uses on average only 6 bits per triangle, can be constructed in linear space and time, and supports all standard random-access and mesh traversal operators in constant time. Similarly to the previously proposed LR (Laced Ring) approach, the Zipper construction reorders vertices and triangles along a nearly Hamiltonian cycle called the ring. The 4.4× storage reduction of Zipper over LR results from three contributions. (1) For most triangles, Zipper stores a 2-bit delta (plus three additional bits) rather than a full 32-bit reference. (2) Zipper modifies the ring to reduce the number of exceptional triangles. (3) Zipper encodes the remaining exceptional triangles using 2.5× less storage. In spite of these large savings in storage, we show that Zipper offers comparable performance to LR and other data structures in mesh processing applications. Zipper may also serve as a compact indexed format for rendering meshes, and hence is valuable even in applications that do not require adjacency information.     

A Universal Performance Chart for CPU Cooling Devices

This article deals with performance evaluation of the discrete ordinates method in terms of its capacity to provide accurate results in solving radiation mode problems with different complexities. The problem formulation is done keeping in view the heat transfer process in an evaporator used in a coal-based thermal power station. The hot gas mass in the evaporator is assumed to be a heat source with two different shapes, spherical and conical. The evaporator walls that are covered with a water cooling jacket are modeled with a convective boundary condition. The gas is assumed to be gray and absorbing–emitting. The solution of the radiative transport equation is carried out using the discrete ordinates method. Parametric studies are performed for a wide range of aspect ratio, extinction coefficient, and convective heat transfer coefficient. The code is validated by comparing the result of discrete ordinates method with the exact and the discrete transfer method for nonradiative as well as radiative equilibrium conditions.     

On the use of the atomic force microscope to monitor physical degradation of polymeric coating surfaces

The atomic force microscope (AFM) was used to monitor changes in surface features of an acrylic melamine coating that was exposed to a variety of conditions. Exposure to ultraviolet (UV) radiation and high relative humidity caused general roughening of the surface and the formation of pits. Further, the damage of the coating surface was much more substantial for exposure to high relative humidity compared to exposure to dry environments. This difference in degradation rates correlated with measurements of chemical degradation determined using infrared spectra that were acquired along with the AFM images. Building Materials Division, 100 Bureau Dr., Stop 8621, Gaithersburg, MD 20899-8621.     

On repairable earthquake resisting archetypes with a view to resiliency objectives and assisted self‐centering

Performance‐based seismic design, as an alternative to conventional methods of approach, has served engineers and the public rather well during the last two decades. Neither approach guaranties catastrophic collapse prevention nor post‐earthquake realignment and repairs (PERR) due to major seismic events. As a result, most code‐compliant buildings can be regarded as relatively safe but practically disposable. The paper presents a new philosophy that leads to sustainable design of new structures and the upgrading of existing earthquake resisting moment frames. Repairability‐based design (RBD) relies on softening and control rather than strength and resistance to elevate seismic performance to economically viable, physical collapse prevention, damage control, and post‐earthquake realignment and repairs. The new approach was inspired by design led analysis (DLA), performance control (PC), and recent developments in rocking core‐moment frame design. DLA is a displacement based method of analysis with built‐in results. PC is the ability to design a structure in such a way as to expect predetermined modes of response at certain stages of loading, extents of damage, and drift ratios. This paper advocates higher performance objectives than current codes of practice do. Several demonstrative examples have been provided.     

Loss of control, self-blame, and depression: An investigation of spouse caregivers of Alzheimer's disease patients.

Tested several predictions derived from the reformulated learned helplessness (RLH) depression model developed by L. Y. Abramson et al (see record 1979-00305-001) and from recent critiques of that model, in a longitudinal study of spouses caring for a husband or wife with Alzheimer's disease. During initial interviews, 68 caregivers (aged 37–85 yrs) rated the uncontrollability of important upsetting events related to their spouse's disease and were scored on an index of internal–external causal attribution (CATN) for those events. In addition, at both the initial and follow-up interviews (n?=?38) about 10 mo later, caregivers were rated for depression, anxiety, and hostility. Results indicate that the indices of loss of control and CATN were more consistently related to depression than to anxiety or hostility, although hostility was related to CATNs. Correlations of the loss of control and CATN variables with depression remained significant after controlling for a measure of the spouse's objective disability. In hierarchical regression analyses, perceived loss of control and its interaction with CATN significantly predicted follow-up depression after controlling for initial depression. The interaction showed that loss of control combined with an internal attribution predicted higher depression than did either one alone. The importance of including specific uncontrollable events when studying the RLH model is emphasized. (36 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A temporal cross section specification of the demand for gasoline using a random coefficient regression model

This paper uses a random coefficient regression approach to estimate the demand for gasoline by pooling cross-sectional (state level) and time series data. The analysis proceeds by estimating two alternative models, namely a stock adjustment model and a flow adjustment model. The two models are estimated using state level data on gasoline consumption, gasoline price, income and the stock of automobiles. The random coefficient specification of each demand model is estimated assuming heteroskedastic disturbances across states, autocorrelated disturbances over time and variable intercept and slope coefficients across states. The resultant price and income elasticities are compared and inferences concerning the ability of the flow adjustment model to approximate the underlying demand function are made.     

Nonlocal quantum information in bipartite quantum error correction

We show how to convert an arbitrary stabilizer code into a bipartite quantum code. A bipartite quantum code is one that involves two senders and one receiver. The two senders exploit both nonlocal and local quantum resources to encode quantum information with local encoding circuits. They transmit their encoded quantum data to a single receiver who then decodes the transmitted quantum information. The nonlocal resources in a bipartite code are ebits and nonlocal information qubits, and the local resources are ancillas and local information qubits. The technique of bipartite quantum error correction is useful in both the quantum communication scenario described above and in fault-tolerant quantum computation. It has application in fault-tolerant quantum computation because we can prepare nonlocal resources offline and exploit local encoding circuits. In particular, we derive an encoding circuit for a bipartite version of the Steane code that is local and additionally requires only nearest-neighbor interactions. We have simulated this encoding in the CNOT extended rectangle with a publicly available fault-tolerant simulation software. The result is that there is an improvement in the “pseudothreshold” with respect to the baseline Steane code, under the assumption that quantum memory errors occur less frequently than quantum gate errors.     

Implementing enterprise resource planning systems: organizational performance and the duration of the implementation

This paper examines the impact of the duration of ERP implementation on firm performance both during and after implementation. Organizations choose either an accelerated implementation approach or a traditional (longer) implementation approach. The former approach gives the organization the advantage of speed, but the disadvantage of fitting its processes to that of a packaged (thus, undifferentiated from competitors) ERP. The latter approach allows the organization to redesign strategy and processes, and thus, search for ways to be unique from its competition. The study uses a regression model to capture the changes in various performance measures during and after implementation between firms that implemented the ERP, using the performance measure of a matched group of firms that did not implement an ERP as a benchmark/control sample, on the basis of the duration of the implementation. Financial data from Compustat, and data on start date and end date of ERP implementation between 1990 and 2005 for firms in the Oil and Gas industry was collected from an ERP vendor. Results show that measures such as return on sales improved after implementation. However, measures such as inventory turnover, which reflect operational benefits, improve during implementation. We find that accelerated implementation confers both operational and strategic benefits. This study highlights the strategic consequences of the different choices of implementation.     

A formal framework for scenario development in support of environmental decision-making

Scenarios are possible future states of the world that represent alternative plausible conditions under different assumptions. Often, scenarios are developed in a context relevant to stakeholders involved in their applications since the evaluation of scenario outcomes and implications can enhance decision-making activities. This paper reviews the state-of-the-art of scenario development and proposes a formal approach to scenario development in environmental decision-making. The discussion of current issues in scenario studies includes advantages and obstacles in utilizing a formal scenario development framework, and the different forms of uncertainty inherent in scenario development, as well as how they should be treated. An appendix for common scenario terminology has been attached for clarity. Major recommendations for future research in this area include proper consideration of uncertainty in scenario studies in particular in relation to stakeholder relevant information, construction of scenarios that are more diverse in nature, and sharing of information and resources among the scenario development research community.