A Physical-Constraint-Preserving Finite Volume WENO Method for Special Relativistic Hydrodynamics on Unstructured Meshes

This paper presents a highly robust third-order accurate finite volume weighted essentially non-oscillatory (WENO) method for special relativistic hydrodynamics on unstructured triangular meshes. We rigorously prove that the proposed method is physical-constraint-preserving (PCP), namely, always preserves the positivity of the pressure and the rest-mass density as well as the subluminal constraint on the fluid velocity. The method is built on a highly efficient compact WENO reconstruction on unstructured meshes, a simple PCP limiter, the provably PCP property of the Harten--Lax--van Leer flux, and third-order strong-stability-preserving time discretization. Due to the relativistic effects, the primitive variables (namely, the rest-mass density, velocity, and pressure) are highly nonlinear implicit functions in terms of the conservative variables, making the design and analysis of our method nontrivial. To address the difficulties arising from the strong nonlinearity, we adopt a novel quasilinear technique for the theoretical proof of the PCP property. Three provable convergence-guaranteed iterative algorithms are also introduced for the robust recovery of primitive quantities from admissible conservative variables. We also propose a slight modification to an existing WENO reconstruction to ensure the scaling invariance of the nonlinear weights and thus to accommodate the homogeneity of the evolution operator, leading to the advantages of the modified WENO reconstruction in resolving multi-scale wave structures. Extensive numerical examples are presented to demonstrate the robustness, expected accuracy, and high resolution of the proposed method.Comment: 56 pages, 18 figure

Circuit design for logic automata

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2009.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Cataloged from student-submitted PDF version of thesis.Includes bibliographical references (p. 143-148).The Logic Automata model is a universal distributed computing structure which pushes parallelism to the bit-level extreme. This new model drastically differs from conventional computer architectures in that it exposes, rather than hides, the physics underlying the computation by accommodating data processing and storage in a local and distributed manner. Based on Logic Automata, highly scalable computing structures for digital and analog processing have been developed; and they are verified at the transistor level in this thesis. The Asynchronous Logic Automata (ALA) model is derived by adding the temporal locality, i.e., the asynchrony in data exchanges, in addition to the spacial locality of the Logic Automata model. As a demonstration of this incrementally extensible, clockless structure, we designed an ALA cell library in 90 nm CMOS technology and established a "pick-and-place" design flow for fast ALA circuit layout. The work flow gracefully aligns the description of computer programs and circuit realizations, providing a simpler and more scalable solution for Application Specific Integrated Circuit (ASIC) designs, which are currently limited by global constraints such as the clock and long interconnects. The potential of the ALA circuit design flow is tested with example applications for mathematical operations. The same Logic Automata model can also be augmented by relaxing the digital states into analog ones for interesting analog computations. The Analog Logic Automata (AnLA) model is a merge of the Analog Logic principle and the Logic Automata architecture, in which efficient processing is embedded onto a scalable construction.(cont.) In order to study the unique property of this mixed-signal computing structure, we designed and fabricated an AnLA test chip in AMI 0.5[mu]m CMOS technology. Chip tests of an AnLA Noise-Locked Loop (NLL) circuit as well as application tests of AnLA image processing and Error-Correcting Code (ECC) decoding, show large potential of the AnLA structure.by Kailiang Chen.S.M

Ultrasonic imaging front-end design for CMUT: A 3-level 30Vpp pulse-shaping pulser with improved efficiency and a noise-optimized receiver

A four-channel analog front-end (AFE) transceiver chip for medical ultrasound imaging is demonstrated. The high voltage transmitter uses a 3-level pulse-shaping technique to deliver over 50% more acoustic power for the same power dissipation, compared to traditional methods. The design requires minimum off-chip components and is scalable for more channels. The receiver is implemented with a transimpedance amplifier (TIA) topology and is optimized for noise, bandwidth and power dissipation. Based on both acoustic and electrical measurements, we demonstrate the Transmitter (Tx) efficiency improvement, Tx beamformation and the pulse-echo response, revealing the system's full functionality.Semiconductor Research Corporation. Focus Center for Circuit and System Solutions (C2S2

The effects of two empathy strategies in design thinking on pre-service teachers’ creativity

Teachers are increasingly encouraged to creatively integrate technology into their classroom instruction as designers of technology-enhanced learning (TEL). However, they are often not competent in designing TEL due to their lack of experience as participatory designers as well as the ill-structure nature of TEL design problem. Design thinking, as a methodology and a framework for the design process, can serve as a guideline for the development of pre-service teachers’ creativity. However, there is a lack of research investigating whether the strategies used in the empathizing stage of the design thinking process affect pre-service teachers’ creativity differently. This study explored the effects of two commonly used empathy strategies, interview and observation, on pre-service teachers’ creativity through a six-week learning design activity for pre-service teachers majoring in Science and Technology Education at a first-tier university in China. The results of this quasi-experimental research showed that the pre-service teachers using the interview empathy strategy performed better in creative problem-solving performance. While there was no significant difference in the pre-service teachers’ creative thinking disposition between the two empathy strategies, the pre-service teachers using the interview strategy reported more positive creative confidence in their creativity than those using the observation strategy. This study suggests future research directions for supporting design thinking–based instructional design

Ultrasonic Imaging Transceiver Design for CMUT: A Three-Level 30-Vpp Pulse-Shaping Pulser With Improved Efficiency and a Noise-Optimized Receiver

This paper demonstrates a four-channel transceiver chip for medical ultrasonic imaging, interfacing to the capacitive micromachined ultrasonic transducers (CMUTs). The high-voltage transmitter (Tx) uses a three-level pulse-shaping technique with charge recycling to improve the power efficiency. The design requires minimum off-chip components and is scalable for more channels. The receiver is implemented with a transimpedance amplifier (TIA) topology and is optimized for tradeoffs between noise, bandwidth, and power dissipation. The test chip is characterized with both acoustic and electrical measurements. Comparing the three-level pulser against traditional two-level pulsers, the measured Tx efficiency shows 56%, 50%, and 43% more acoustic power delivery with the same total power dissipation at 2.5, 3.3, and 5.0 MHz, respectively. The CMUT receiver achieves the lowest noise efficiency factor compared with that of the literature (2.1 compared to a previously reported lowest of 3.6, in units of mPA ·√(mW/Hz). In addition, the transceiver chip is tested as a complete system for medical ultrasound imaging applications, in experiments including Tx beamformation, pulse-echo channel response characterization, and ultrasonic Doppler flow rate detection.Semiconductor Research Corporation. Focus Center for Circuit and System Solutions (C2S2

Reconfigurable Asynchronous Logic Automata (RALA)

Computer science has served to insulate programs and programmers from knowledge of the underlying mechanisms used to manipulate information, however this fiction is increasingly hard to maintain as computing devices decrease in size and systems increase in complexity. Manifestations of these limits appearing in computers include scaling issues in interconnect, dissipation, and coding. Reconfigurable Asynchronous Logic Automata (RALA) is an alternative formulation of computation that seeks to align logical and physical descriptions by exposing rather than hiding this underlying reality. Instead of physical units being represented in computer programs only as abstract symbols, RALA is based on a lattice of cells that asynchronously pass state tokens corresponding to physical resources. We introduce the design of RALA, review its relationships to its many progenitors, and discuss its benefits, implementation, programming, and extensions.National Science Foundation (U.S.) Center for Bits and AtomsUnited States. Army Research Office (Grant number W911NF-08-1-0254)United States. Army Research Office (Grant number W911NF-09-1-0542

Sustainable and Intelligent Phytoprotection in Photovoltaic Agriculture: New Challenges and Opportunities

Photovoltaic Agriculture (PA) is a new management system combining industry with modern agriculture that can effectively reduce the competition for limited land resource usage between electric power production and agricultural production. However, PA has been facing the challenge of managing plant protection measures because it is difficult to monitor plants grown under the photovoltaic panels by remote sensing satellites and pesticide applications using drones. To overcome this challenge, Solar Insecticidal Lamps (SILs) can be used for phytoprotection in PA. However, to effectively use SILs in PA, it is important to identify a suitable field location to maintain strong wireless communication signals. In this paper, two testbeds were designed and a series of experiments in PA was performed. The results indicate that there is considerable interference exists around the confluence box. A higher interference seriously reduces the Packet Reception Rate (PRR) of the nearby node, which is an important constraint for deploying wireless sensors in PA. Finally, new challenges and future research opportunities are proposed

Analysis of the Application of Accounting Information Systems of Cash Receipt on the Rsia Kasih Ibu Manado

The accounting information system on cash receipt is an information system that is important to improve the quality and performance of a hospital. The application of the supervision/control system in an organization will provide many benefits to the management in running the business, as well as to maintain the existence of the company in facing competitors. This study aims to analyze the application of cash receipts accounting information systems at RSIA Kasih Ibu Manado. RSIA Kasih Ibu, is one of the agencies that deal with health services for mothers and children. The method used is descriptive method. The results shows, the accounting information systems, especially cash receipts on the RSIA Kasih Ibu has been in accordance with the basic elements of accounting information systems. This is evident by the existence of good records and adequate internal control. It is recommended that the accounting information system in the financial department computerized information system is implemented in accordance with the required accounting information systems also maintain and improve the information system that has been implemented, so that the hospital can have a good quality in service, administration and finance. Keywords: accounting information systems, cash receipt