A web-based 3D ontology navigation system for spinal disease diagnosis

The Journal of Supercomputing - This paper presents a web-based three-dimensional (3D) navigation system for a spinal disease ontology using a 3D virtual human spine. The 3D navigation system...     

Real-time approximation of molecular interaction interfaces based on hierarchical space decomposition

The interaction interface between two molecules can be represented as a bisector surface equidistant from the two sets of spheres of varying radii representing atoms. We recursively divide a box containing both sphere-sets into uniform pairs of sub-boxes. The distance from each new box to each sphere-set is conservatively approximated by an interval, and the number of sphere-box computations is greatly reduced by pre-partitioning each sphere-set using a kd-tree. The subdivision terminates at a specified resolution, creating a box partition (BP) tree. A piecewise linear approximation of the bisector surface is then obtained by traversing the leaves of the BP tree and connecting points equidistant from the sphere-sets. In 124 experiments with up to 16,728 spheres, a bisector surface with a resolution of 1/2⁴ of the original bounding box was obtained in 28.8 ms on average.     

OpenGL ES 1.1 implementation based on OpenGL

In this paper, we present an efficient way of implementing OpenGL ES 1.1 3D graphics API library for the environments with hardware-supported OpenGL facility, typically as desktop PCs. Although OpenGL ES was started from the existing OpenGL features, it rapidly became the standard 3D graphics library customized for embedded systems through introducing fixed-point arithmetic operations, buffer management with fixed-point data type supports, completely new texture mapping functions and others. Currently, it is the official 3D graphics API for Google Android, Apple iPhone, Sony PlayStation3, etc. In this paper, we achieved improvements on the arithmetic operations for the fixed-point number representation, which is the most characteristic data type for OpenGL ES 1.1. For the conversion of fixed-point data types to the floating-point number representations for the underlying OpenGL, we show the way of efficient conversion processes even with satisfying OpenGL ES standard requirements. We also introduced a specialized memory management scheme to manage the converted data from the buffer containing fixed-point numbers. In the case of texture processing, the requirements in both standards are quite different, and thus we used completely new software-implementations. Our final implementation of OpenGL ES library provides all of more than 200 functions in the standard specification and passed its conformance test, to show its compliance with the standard. From the efficiency point of view, we measured its execution times for several OpenGL ES-specific application programs and achieved remarkable improvements.     

AlexVG: An OpenVG implementation with SVG-Tiny support

Embedded systems and web browsers have started to provide two-dimensional vector graphics features, to finally support scalability of graphics outputs, while traditional graphics systems have focused on the raster and bitmap operations. Nowadays, SVG and Flash are actively used and OpenVG from Khronos group plays the role of a de facto low-level API standard to support them. In this paper, we represent the design and implementation process and the final results of the first commercial OpenVG implementation, AlexVG. From its design stage, our implementation aims at the cooperation with SVG-Tiny, another de facto standard for embedded systems. Currently, our overall system provides not only the OpenVG core features but also a variety of OpenVG application programs and SVG-Tiny media file playing capabilities. For the conformance with the standard specifications, our system completely passed the whole OpenVG conformance test suites and the graphics output portions of the SVG-Tiny conformance test suites. From the performance point of view, we focused on the efficiency and effectiveness especially on the mobile phones and embedded devices with limited resources. As the result, it showed impressive benchmarks on the small-scale CPUs such as ARMs, even without neither any other libraries nor acceleration hardware. We had started commercial services of our AlexVG products since September 2005, and successfully entered the retail market with a good deal of mobile phones up to the present time.     

Feasibility test of an electromagnetically driven valve actuator for glaucoma treatment

Although conventional glaucoma implants have a capability of pressure regulation, they cannot maintain the intraocular pressure (IOP) desired for different patients. In this paper, we present an analysis of the operation of a conventional implant using a bond graph and show its defects and the limitations of a conventional valve analytically. On the basis of the analysis, the design and fabrication of an active valve actuator is performed considering actuation principles, resistance elements, and control methods. An electromagnetic actuator is used for realizing the active resistance element. A passive resistance element is also included in in order to reduce power consumption. A pulsewidth modulation (PWM) control method is used for enhancing the power consumption saving. Finally, we describe experiments and simulations with the fabricated valve actuator in an in vitro environment, and estimate the in vivo performance from the in vitro experimental results.     

A Z-map update method for linearly moving tools

In numerically controlled (NC) machining simulation, a Z-map has been frequently used for representing the workpiece. Since the Z-map is usually represented by a set of z-axis aligned vectors, the machining process can be simulated through calculating the intersection points between the vectors and the surface swept by a machining tool. In this paper, we present an efficient method to calculate those intersection points when automatically programmed tool-type tools move along a linear tool path. Each of the intersection points can be expressed as the solution of a system of non-linear equations. We transform this system of equations into a single-variable equation, and calculate the candidate interval in which the unique solution exists. We prove the existence of a solution and its uniqueness in this candidate interval. Based on these properties, we can effectively apply numerical methods to finally calculate the solution of the non-linear equations within a given precision. The whole process of NC simulation is achieved by updating the Z-map properly. Our method can improve accuracy greatly while increasing processing time negligibly in comparison with previous Z-map update methods, making it possible to verify the tool path more accurately and reliably.     

Robust Sliding Mode Control of a Vapor Compression Cycle

This paper deals with the development of a mathematical dynamic model and observer-based set point control of a vapor compression cycle (VCC) system. The mean void fraction and moving boundary control volumes in a heat exchanger (HEX) are used for a lumped parameter model of an air conditioning system. A multi-input multi-output (MIMO) dynamic model of the VCC is presented in a nonlinear state space representation and is reformulated into a linearized regular form for control design. A modified observer-based controller with sliding mode control (SMC) is introduced to attenuate the effects of observing approximation errors and external disturbances. In the design of the discontinuous controller, a new type of gain function is introduced to reduce the time to reach the sliding mode compared to a conventional discontinuous gain. The proposed control methodology ensures uniformly ultimately bounded tracking results of the desired low pressure and suction superheat. A simulation of controlling the VCC illustrates the effectiveness and performance in the presence of disturbances.