Fabrication of high-aspect-ratio microscale Ta mold inserts with micro electrical discharge machining

We report fabrication of microscale Ta mold inserts by micro-electrical-discharge-machining (μEDM). Morphology, chemistry, and structure of the near-surface region of as-μEDMed Ta blanks have been characterized by scanning electron microscopy, X-ray photoelectron spectroscopy, and transmission electron microscopy. A TaC surface layer forms on as-μEDMed Ta surfaces. This altered surface layer was removed by electro-chemical-polishing. Further modification of Ta insert surfaces was accomplished by deposition of a conformal Ti-containing hydrogenated carbon coating. We demonstrate successful replication of high-aspect-ratio microscale structures in Al and Cu by compression molding with such surface-engineered Ta mold inserts.     

An order of magnitude faster isosurface rendering in software on aPC than using dedicated, general purpose rendering hardware

The purpose of this work is to compare the speed of isosurface rendering in software with that using dedicated hardware. Input data consist of 10 different objects from various parts of the body and various modalities (CT, MR, and MRA) with a variety of surface sizes (up to 1 million voxels/2 million triangles) and shapes. The software rendering technique consists of a particular method of voxel-based surface rendering, called shell rendering. The hardware method is OpenGL-based and uses the surfaces constructed from our implementation of the Marching Cubes algorithm. The hardware environment consists of a variety of platforms, including a Sun Ultra I with a Creator3D graphics card and a Silicon Graphics Reality Engine II, both with polygon rendering hardware, and a 300 MHz Pentium PC. The results indicate that the software method (shell rendering) was 18 to 31 times faster than any hardware rendering methods. This work demonstrates that a software implementation of a particular rendering algorithm (shell rendering) can outperform dedicated hardware. We conclude that, for medical surface visualization, expensive dedicated hardware engines are not required. More importantly, available software algorithms (shell rendering) on a 300 MHz Pentium PC outperform the speed of rendering via hardware engines by a factor of 18 to 31     

Model-based segmentation and tracking of head-and-shoulder video objects for real time multimedia services

A statistical model-based video segmentation algorithm is presented for head-and-shoulder type video. This algorithm uses domain knowledge by abstracting the head-and-shoulder object with a blob-based statistical region model and a shape model. The object segmentation problem is then converted into a model detection and tracking problem. At the system level, a hierarchical structure is designed and spatial and temporal filters are used to improve segmentation quality. This algorithm runs in real time over a QCIF size video, and segments it into background, head and shoulder three video objects on average Pentium PC platforms. Due to its real time feature, this algorithm is appropriate for real time multimedia services such as videophone and web chat. Simulation results are offered to compare MPEG-4 performance with H.263 on segmented video objects with respects to compression efficiency, bit rate adaptation and functionality.     

Low temperature deposited titanium boride thin films and their application to surface engineering of microscale mold inserts

Titanium boride thin films were deposited at low temperatures by balanced magnetron sputtering and inductively coupled plasma (ICP) assisted balanced magnetron sputtering. The chemical composition, surface morphology, structure, and mechanical properties of titanium boride thin films were characterized by X-ray photoelectron spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy, and instrumented nanoindentation. As compared to titanium boride films deposited by balanced magnetron sputtering, the increase in plasma density surrounding the substrate surface during film growth afforded by the ICP assist causes significant film densification and mechanical property improvement. The morphology of titanium boride thin films deposited onto microscale non-flat Ta substrates and their effectiveness as barrier coatings for microscale compression molding of Al was characterized by focused ion beam sectioning and SEM. The present results show the potential of low-temperature deposited, conformal, titanium boride thin films for engineering surfaces of microscale mold inserts for microscale pattern replication in reactive metals by compression molding.     

Trimming implicit surfaces

Algorithms for trimming implicit surfaces yielding surface sheets and stripes are presented. These two-dimensional manifolds with boundaries result from set-theoretic operations on an implicit surface and a solid or another implicit surface. The algorithms generate adaptive polygonal approximation of the trimmed surfaces by extending our original implicit surface polygonization algorithm. The presented applications include modeling several spiral shaped surface sheets and stripes (based on M. Eschers artworks) and extraction of ridges on implicit surfaces. Another promising application of the presented algorithms is modeling heterogeneous objects as implicit complexes.     

Metal micromolding: further experiments and preliminary finite element analysis

We report results of instrumented microscale compression molding experiments on Al with Ta mold inserts. The Ta inserts have high-aspect-ratio microscale structures fabricated by micro-electrical-discharge-machining. These microscale structures were further surface engineered by electrochemical polishing, followed by deposition of a conformal amorphous hydrogenated carbon based coating. The molding response of Al, in terms of molding force versus insert displacement, was measured in situ with a high-vacuum, instrumented, compression molding apparatus, and rationalized with a simple model on the mechanics of molding. Molding response was further studied numerically through finite element analysis.     

Luminescent dichroic‐dye‐doped cholesteric liquid‐crystal displays

Abstract— LCDs based on a luminescent dichroic‐dye‐doped non‐absorbing cholesteric LC with positive dielectric anisotropy is proposed. In the initial state, the orientation of the dye molecules provides effective light absorption and irradiation. By applying an electric field to the cell, the absorption and thus the luminescence is absent. A two‐color luminescence could be achieved by sandwiching two cells: the upper cell consists of a cholesteric LC with two dyes (sensitizer and emitter) and is used with an applied voltage (active cell); the lower cell consists of a cholesteric LC doped with one dye and works without applying a voltage (passive cell). The performance characteristics of luminescent dye‐doped cholesteric‐LCDs were investigated.     

Injection molding and injection compression molding of three-beam grating of DVD pickup lens

The objective of this paper is to investigate the application of injection molding and injection compression molding processes to produce diffraction gratings. A mold was designed to produce a diffraction rating connected with the fixed bushing. The combined part was verified to have a good diffraction performance. Integrated grating eliminates the assembly cost and error. Photolithography was applied to make the mold insert. The Taguchi method and parametric analysis were applied to study the effects of molding parameters on grating quality. The design, fabrication of structured mold surfaces and the results of the replication by injection molding (IM) and injection compression molding (ICM) are presented and compared. The diffraction angle of ICM grating is more accurate than that of IM grating. Grating made by ICM has a much smaller warpage than that made by IM. The diffraction pattern shows that ICM is a better process than IM to replicate a diffraction grating.     

基于LabVIEW的单片机温度测控系统设计

利用LabVIEW开发环境设计PC上位机的监控界面，上位机通过串行口与89C51单片机通信，从而实现对过程参数的测量和控制。该测控系统设计简单，简化了系统硬件结构，并且易于修改，具有很好的可扩展性。     

A PC-based distributed multiple display virtual reality system

In this paper, a PC-based distributed multiple-display virtual reality system is constructed. The system is a PC-based CAVE environment. Five PCs are used in this system; one is the master responsible for receiving user's input signals, the others are clients for images rendering. Devices are added to synchronize the RGB signals from client PCs.

A software library is developed to drive the system properly. The software is designed in object-oriented language and flexibility for different interface devices is considered.

With the proposed system, developers can easily elaborate PC-based virtual reality applications and build PC virtual worlds at much lower cost.     

Effects of geometric parameters for superhydrophobicity of polymer surfaces fabricated by precision tooling machines

Effects of geometric parameters are regarded as indicating factors that affect super hydrophobic surfaces. Micro-sized pillar-type structures were prepared using a precision tooling machine that was able to fabricate various structures precisely on polymer surfaces. The tooling machine has many advantages of low cost, short processing time, and precise control of geometric parameters compared to other micro-manufacturing techniques of polymers such as injection molding, replica molding, and hot embossing. Hydrophobicity of the polymer affected by surface conditions and geometric properties is considered. Furthermore, to examine the effects of low surface energy, we coated the CF₂-based fluoropolymer onto various pillar structures. The some of the coated surfaces show the superhydrophobicity with a water contact angle greater than 150°. The hydrophobic and oleophobic properties are regarded as verifying the transition of the energy state and the tendency of wetting behavior depending on the geometric parameters and low surface energy property.     

A short route of covalent biofunctionaliztion of silicon surfaces

Covalently attached organic monolayers on etched Si(1 1 1) surfaces were prepared by heating solutions of 1-alkenes and 1-alkynes in a refluxing mesitylene. Surface modification was monitored by measurement of the static water contact angle, X-ray photoelectron spectroscopy (XPS), infrared reflection absorption spectroscopy (IRRAS), and atomic force microscopy (AFM). Flat and clean N-hydroxysuccinimide (NHS)-ester-terminated/1-decyl mixed monolayers were covalently attached in one step onto a silicon surface. This procedure allows a mild and rapid functionalization of the surface by substitution of the NHS-ester moieties with amines at room temperature. The NHS-ester groups were shown to be fully intact onto the surface. The surface reactivity of the NHS-ester moieties toward amines was qualitatively and quantitatively evaluated via the reaction with methoxytetraethyleneglycolamine (TEGamine) and finally functionalized with single strand and complete DNA molecules.Moreover, domains of DNA were selectively immobilized, on silicon surface making use of TEGamine, which acts as protein repelling agent and therefore prevented non-specific DNA adsorption. The resulting DNA-modified surfaces have shown excellent specificity, and chemical and thermal stability under hybridization conditions.     

Effects of Fabrication Process Parameters on the Properties of Cyclic Olefin Copolymer Microfluidic Devices

Among the materials used for fabricating microfluidic devices, plastics have been increasingly employed in the past few years. Although several methods for fabricating plastic devices have appeared in the literature, reports typically indicate one set of conditions that yield functional devices; little data are available detailing how results are affected by their changes in the process variables. We report in this paper a systematic study of fabrication process parameters including compression rate, molding temperature, and the force used by a hydraulic press, as well as their effects on the device properties. Using cyclic olefin copolymers as the molding material, we found that the device thickness decreased when the molding temperature and compression force increased. Fidelity in the pattern transfer from a master to a device was confirmed by the reproduction of nanostructures and channel depth/shape. Pattern transfer fidelity appeared to be independent of the molding temperature and compression force, at least in the range of conditions we investigated. Stress whitening (or crazing) on the device surface was found to be related to the molding temperature and the cooling rate of the mold/device assembly. The bond strength between the layers of a laminated device was determined to be a function of the lamination temperature. In addition, we demonstrated the utility of a plastic microfluidic device by separating proteins. 1678     

Reverse engineering with subdivision surfaces

Reverse engineering is concerned with the reconstruction of surfaces from three-dimensional point clouds originating from laser-scanned objects. We present an adaptive surface reconstruction method providing a hierarchy of quadrilateral meshes adapting surface topology when a mesh is refined. This way, a user can choose a model with proper resolution and topology from the hierarchy without having to run the algorithm multiple times with different parameters. The multiresolution mesh representation can be used subsequently for view-dependent rendering and wavelet compression.     

Microscale compression molding of Al with surface engineered LiGA inserts

High temperature compression molding of Al plates with high-aspect-ratio microscale mold inserts was carried out. The bulk of the mold insert consists of electrodeposited Ni, fabricated with the LiGA (Lithographie, Galvanoformung, Abformung) technique. Both as-fabricated Ni inserts and Ni inserts conformally coated with a Ti-containing hydrocarbon (Ti-C:H) coating were used for Al micromolding at temperatures 450 °C. In-situ measurements of compression molding force, demolding force, and insert displacement were carried out. Insert conditions and microscale features generated on Al plates by molding were examined. Our results show that as-fabricated Ni inserts are not suitable for Al micromolding, and that Ni inserts conformally coated with a Ti-C:H coating allow repeated Al micromolding with 100% transfer of microscale features from the insert to the molded Al plate. Our results demonstrate, to our knowledge for the first time, successful replication of high-aspect-ratio Al microscale structures by high temperature compression micromolding.DMC and WJM gratefully acknowledge partial project support from NSF through grant DMI-0124441 and the Louisiana Board of Regents through contracts LEQSF(2001–04)-RD-A-07. Ni inserts used in this work were fabricated by Mezzo Systems Inc. using facilities at Lsu CAMD.     

The application of surface visibility and moldability to parting line generation

In molding, casting or forging processes, part surfaces are formed by the core, cavity and local tools in molding/casting or by the upper and lower dies and local tools in forging. In computer-aided design of dies and molds, automatic identification of surfaces molded/formed by these different tooling components is critical since the generation of parting lines depends on these surfaces, which would further influence the determination of parting surfaces, the creation of core and cavity blocks and the entire mold structure. In this paper, the surface partability and visibility are first proposed and its moldability is next presented. Considering the molding process as an instance, the concepts of core-, cavity- and the local tool-molded surfaces are defined. A methodology based on surface visibility and moldability to determine the potentially and actually moldable surfaces of these groups is developed. Since the generation of parting lines is a crucial preliminary design step in mold/die design life cycle, a new approach to determining the parting lines based on the proposed methodology is presented. A case study is used to test the methodology and approach, and to validate the efficiency in parting line generation of molded parts.     

WHNMR—a universal NMR application package

A PC-based NMR off-line data processing system is developed and described in detail. With this software system, one-dimensional (1D), two-dimensional (2D), and NMR imaging (MRI) data can be processed easily, and give reliable results. By the applications of this system, a versatile software interface is set up to achieve data exchanging and integrated usage with other PC application software and aids the PC to become an effective and powerful workstation.     

A PC-based open robot control system: PC-ORC

An open architecture manufacturing system pursues to integrate manufacturing components on a single platform. Therefore, a particular component can be easily added and/or replaced. In this paper, a modular and object-oriented approach for the PC-based open robot control (PC-ORC) system is investigated. A standard reference model for controlling robots, which consists of a hardware platform, an operating system module, and various application software modules, is first proposed. Then, PC-ORC system, which can reconfigure the control system in various production environments, is developed. The PC-ORC is constructed based upon the object-oriented method. Hence, it allows an easy implementation and modification of various modules. The PC-ORC consists of basic software, application objects, and additional hardware devices on a PC platform. Finally, by applying the proposed PC-ORC to a SCARA robot, the performance of the PC-ORC is examined.     

The application of surface demoldability and moldability to side-core design in die and mold CAD

In casting, molding and forming processes, the surface geometries of the fabricated products are formed/molded by different functional components of tooling. In plastic injection molding, they are molded by core, cavity or side-cores. In die and mold CAD, how to identify the product surfaces formed/molded by the corresponding tool components for a given product CAD model is critical, as it affects the determination of parting directions, parting lines and parting surfaces, the generation of core and cavity blocks, and finally the design of side-cores and their actuating mechanisms. In this paper, the concepts of surface visibility, demoldability, and moldability are first presented and formulated. The surfaces formed/molded by core, cavity and side-cores are then defined based on the plastic injection molding process. The methodology to identifying and classifying them is further developed. By employing the proposed notions of the demoldability map of surfaces and undercut features, the most preferred demolding direction, the grouping of undercut features, and how to conduct the side-core design is articulated succinctly, and the detailed procedures and processes are presented. Through an industrial case study, the developed methodology for side-core design is systematically presented and the feasibility of the developed approaches is verified.