Index rendering: hardware-efficient architecture for 3-D graphics in multimedia system

Real-time three-dimensional (3D) graphics is emerging rapidly in multimedia applications, but it suffers from requirements for huge computation, high bandwidth, and large buffer. In order to achieve hardware efficiency for 3D graphics rendering, we propose a novel approach named index rendering. The basic concept of index rendering is to realize a 3D rendering pipeline by using asynchronous multi-dataflows. Triangle information can be divided into several parts with each part capable of being transferred independently and asynchronously. Finally, all data are converged by the index to generate the final image. The index rendering approach can eliminate unnecessary operations in the traditional 3D graphics pipeline, the unnecessary operations are caused by the invisible pixels and triangles in the 3D scene. Previous work, deferred shading, eliminates the operations relating to invisible pixels, but it requires huge tradeoffs in bandwidth and buffer size. With index rendering, we can eliminate operations on both invisible pixels and triangles with fewer tradeoffs as compared with the deferred shading approach. The simulation and analysis results show that the index rendering approach can reduce 10%-70% of lighting operations when using the flat and Gouraud shading process and decrease 30%-95% when using Phong shading. Furthermore, it saves 70% of buffer size and 50%-70% of bandwidth compared with the deferred shading approach. The result also indicates that this approach of index rendering is especially suitable for low-cost portable rendering devices. Hence, index rendering is a hardware-efficient architecture for 3D graphics, and it makes rendering hardware more easily integrated into multimedia systems, especially system-on-a-chip (SOC) designs.     

Optimization of 2‐stage cooperative spectrum for cognitive radio networks using multi‐antenna energy detectors

Cooperative spectrum sensing, a kind of spectrum sensing scheme in cognitive radio (CR), uses multiple CR relays. To increase performance, this study uses multi‐antenna CR relays and beam‐forming reception. The required bandwidth for reporting channels in cooperative spectrum sensing is crucial. Two‐stage cooperative spectrum sensing is proposed to increase performance without increasing the required bandwidth. The cooperative spectrum sensing is also optimized to allow the CR networks to facilitate the best decision‐making. This study determines the detection performance when beam‐forming reception is used. Numerical simulations are used to validate the effectiveness of the method. It is shown that beam‐forming reception outperforms square‐law combining (SLC) for low SNR values. This study proposes a 2‐stage cooperative spectrum sensing method, which uses multi‐antenna CR relays and beam‐forming reception. The cooperative spectrum sensing is also optimized to allow the CR networks to facilitate the best decision‐making. Numerical simulations are used to validate the effectiveness of the method.     

Efficient Dispersants for TiO2 Nanopowder in Organic Suspensions

This article discusses the appropriate dispersant for titania (TiO₂) nanopowder in organic‐based suspensions. Four types of oleyl‐based dispersants, namely, oleyl alcohol, oleic acid, oleylamine, and oleyl phosphate, which have the functional groups hydroxyl (–OH), carboxyl (–COOH), amino (–NH₂), and phosphorous [–P(=O)(OH)₂], respectively, were compared for their ability to disperse TiO₂. Experimental results for zeta potential, adsorption, FT‐IR spectroscopy, and rheology, as well as theoretical calculations, indicate that dispersants with –P(=O)(OH)₂ and –NH₂ were more efficient than those with –COOH or –OH. The primary reason for this difference is related to the different interactions of TiO₂ with various dispersants and to different dispersion mechanisms. In addition to the major functional groups, –OH in the chemical structure of dispersants was important, as it might have other effects such as destabilization of the suspensions.     

Out‐of‐Core Simplification and Crack‐Free LOD Volume Rendering for Irregular Grids

We propose a novel out‐of‐core simplification and level‐of‐detail (LOD) volume rendering algorithm for large irregular grids represented as tetrahedral meshes. One important feature of our algorithm is that it creates a space decomposition as required by I/O‐efficient simplification and volume rendering, and simplifies both the internal and boundary portions of the sub‐volumes progressively by edge collapses using the (extended) quadric error metric, while ensuring any selected LOD mesh to be crack‐free (i.e., any neighboring sub‐volumes in the LOD have consistent boundaries, and all the cells in the LOD do not have negative volumes), with all computations performed I/O‐ejficiently. This has been an elusive goal for out‐of‐core progressive meshes and LOD visualization, and our novel solution achieves this goal with a theoretical guarantee to be crack‐free for tetrahedral meshes. As for selecting a desirable LOD mesh for volume rendering, our technique supports selective refinement LODs (where different places can have different error bounds), in addition to the basic uniform LODs (where the error bound is the same in all places). The proposed scalar‐value range and view‐dependent selection queries for selective refinement are especially effective in producing images of the highest quality with a much faster rendering speed. The experiments demonstrate the efficacy of our new technique.     

Intensive Exposure of Functional Rings of a Polymeric Hole‐Transporting Material Enables Efficient Perovskite Solar Cells

A variety of dopant‐free hole‐transporting materials (HTMs) is effectively applied in perovskite solar cells (PSCs); however, HTMs with the additional function of HTM/perovskite interfacial optimization that is crucial to their photovoltaic performance are really limited. In this work, the design of an HTM bearing an intensive exposure of its functional aromatic rings to perovskite layer via side‐chain engineering is attempted. With an edge‐on orientation and a short distance to perovskite, this HTM was expected to display an excellent ability to extract holes from and passivate defects in the perovskite layer. To demonstrate this strategy, an alternating copolymer was constructed with a 2,5‐di‐2‐ethylhexyloxy‐1,4‐phenylene unit and a bithiophene unit, and the PSC based on this polymer showed an ultrahigh short‐circuit current density of 25.50 mA cm^?2, which was the highest so far presented by dopant‐free organic HTMs. A comparable power conversion efficiency of 19.68% (certified: 19.5%) to that of a control 2,2′,7,7′‐tetrakis(N,N‐di‐p‐methoxyphenylamine)‐9,9′‐spirobifluorene (spiro‐OMeTAD) device (19.81%) was thus obtained, which is the highest value ever reported for mesoporous PSCs based on dopant‐free polymeric HTMs.     

Extending the two‐stage information systems continuance model: incorporating UTAUT predictors and the role of context

This study presents two extensions to the two‐stage expectation‐confirmation theory of information systems (IS) continuance. First, we expand the belief set from perceived usefulness in the original IS continuance model to include three additional predictors identified in the unified theory of acceptance and use of technology, namely effort expectancy, social influence and facilitating conditions. Second, we ground the IS continuance model in the context of transactional systems that involve transmission of personal and sensitive information and include trust as a key contextual belief in the model. To test the expanded IS continuance model, we conducted a longitudinal field study of 3159 Hong Kong citizens across two electronic government (e‐government) technologies that enable citizens' access to government services. In general, the results support the expanded model that provides a rich understanding of the changes in the pre‐usage beliefs and attitudes through the emergent constructs of disconfirmation and satisfaction, ultimately influencing IS continuance intention. Finally, we discuss the theoretical and practical implications of the expanded model.     

A Unified Approach to Submicron DC MOS Transistor Modeling for Low-Voltage ICs

A unified single-equation approach for the MOS transistordrain current modeling for energy-efficient submicron MOS circuitsis presented. Instead of three sets of separate equations forthe triode, saturation, and weak inversion regions, only a continuousexpression which is valid to describe the behavior of drain currentand the derivatives in all operation regions can be realizedby using a combination of hyperbola, sigmoid, and interpolationmethods. The model expression can predict accurate results forthe current, output conductance, and transconductance with continuousand smooth characteristics. The simulation results agree wellwith experimental data.     

Differentiated Service Provision in Optical CDMA Network Using Power Control

A simple scheme to use power control for differentiated service provision is proposed for the optical code-division multiple-access network. The main advantages of this scheme are: 1) Interference from other users can be eliminated theoretically. 2) The decoder with simple configuration can be used as compared to that in a previous power control scheme. 3) The design procedure of various service requirements in one network is simplified.