OpenRaiser/Intern-Atlas huggingface dataset:
Climate modification directed by control theory
Venue: arXiv cs.OH 2008
Year: 2008

Climate modification measures to counteract global warming receive some more new attentions in these years. Most current researches only discuss the impact of these measures to climate, but how to design such a climate regulator is still unknown. This paper shows the control theory could give the systematic direction for climate modification. But the control analyzing also reveals that climate modifications should only be regarded as a last-ditch measure.
An Approach to Learning Research with a Wireless Sensor Network in an Outdoor Setting
Venue: arXiv cs.CY 2008
Year: 2008

Automated collection of environmental data may be accomplished with wireless sensor networks (WSNs). In this paper, a general discussion of WSNs is given for the gathering of data for educational research. WSNs have the capability to enhance the scope of a researcher to include multiple streams of data: environmental, location, cyberdata, video, and RFID. The location of data stored in a database can allow reconstruction of the learning activity for the evaluation of significance at a later time. A brief overview of the technology forms the basis of an exploration of a setting used for outdoor learning.
Plat_Forms -- a contest: The web development platform comparison
Venue: arXiv cs.SE 2008
Year: 2008

"Plat_Forms" is a competition in which top-class teams of three programmers compete to implement the same requirements for a web-based system within 30 hours, each team using a different technology platform (Java EE, .NET, PHP, Perl, Python, or Ruby on Rails). The results will provide new insights into the real (rather than purported) pros, cons, and emergent properties of each platform. The evaluation will analyze many aspects of each solution, both external (usability, functionality, reliability, performance, etc.) and internal (structure, understandability, flexibility, etc.).
Bounds for self-stabilization in unidirectional networks
Venue: arXiv cs.DS 2008
Year: 2008

A distributed algorithm is self-stabilizing if after faults and attacks hit the system and place it in some arbitrary global state, the systems recovers from this catastrophic situation without external intervention in finite time. Unidirectional networks preclude many common techniques in self-stabilization from being used, such as preserving local predicates. In this paper, we investigate the intrinsic complexity of achieving self-stabilization in unidirectional networks, and focus on the classical vertex coloring problem. When deterministic solutions are considered, we prove a lower bound of $n$ states per process (where $n$ is the network size) and a recovery time of at least $n(n-1)/2$ actions in total. We present a deterministic algorithm with matching upper bounds that performs in arbitrary graphs. When probabilistic solutions are considered, we observe that at least $Δ+ 1$ states per process and a recovery time of $Ω(n)$ actions in total are required (where $Δ$ denotes the maximal degree of the underlying simple undirected graph). We present a probabilistically self-stabilizing algorithm that uses $\mathtt{k}$ states per process, where $\mathtt{k}$ is a parameter of the algorithm. When $\mathtt{k}=Δ+1$, the algorithm recovers in expected $O(Δn)$ actions. When $\mathtt{k}$ may grow arbitrarily, the algorithm recovers in expected O(n) actions in total. Thus, our algorithm can be made optimal with respect to space or time complexity.
Design Methodology and Manufacture of a Microinductor
Venue: arXiv cs.OH 2008
Year: 2008

Potential core materials to supersede ferrite in the 0.5-10 MHz frequency range are investigated. The performance of electrodeposited nickel-iron, cobalt-iron-copper alloys and the commercial alloy Vitrovac 6025 have been assessed through their inclusion within a custom-made solenoid microinductor. Although the present inductor, at 500 KHz, achieves 77% power efficiency for 24.7W/cm3 power density, an optimized process predicts a power efficiency of 97% for 30.83W/cm3 power density. The principle issues regarding microinductor design and performance are discussed.
Micro Embossing of Ceramic Green Substrates for Micro Devices
Venue: arXiv cs.OH 2008
Year: 2008

Multilayered ceramic substrates with embedded micro patterns are becoming increasingly important, for example, in harsh environment electronics and microfluidic devices. Fabrication of these embedded micro patterns, such as micro channels, cavities and vias, is a challenge. This study focuses on the process of patterning micro features on ceramic green substrates using micro embossing. A ceramic green tape that possessed near-zero shrinkage in the x-y plane was used, six layers of which were laminated as the embossing substrate. The process parameters that impact on the pattern fidelity were investigated and optimized in this study. Micro features with line-width as small as several micrometers were formed on the ceramic green substrates. The dynamic thermo-mechanical analysis indicated that extending the holding time at certain temperature range would harden the green substrates with little effect on improving the embossing fidelity. Ceramic substrates with embossed micro patterns were obtain d after co-firing. The embedded micro channels were also obtained by laminating the green tapes on the embossed substrates.
Simulation of an Electrostatic Energy Harvester at Large Amplitude Narrow and Wide Band Vibrations
Venue: arXiv cs.OH 2008
Year: 2008

An electrostatic in-plane overlap varying energy harvester is modeled and simulated using a circuit simulator. Both linear and nonlinear models are investigated. The nonlinear model includes mechanical stoppers at the displacement extremes. Large amplitude excitation signals, both narrow and wide band, are used to emulate environmental vibrations. Nonlinear behavior is significant at large displacement due to the impact on mechanical stoppers. For a sinusoidal excitation the mechanical stoppers cause the output power to flatten and weakly decrease. For a wide band excitation, the output power first increases linearly with the power spectral density of the input signal, then grows slower than linearly.
Design and Analysis of a Chaotic Micromixer with Vortices Modulation
Venue: arXiv cs.OH 2008
Year: 2008

A novel design for vortex modulation of a passive chaotic micromixer, named a circulation-disturbance micromixer (CDM), has been achieved and analyzed experimentally and numerically. The systematic numerical analyses - topological flow characteristics and particle tracking method - have been developed, that enable visualization of detailed mixing patterns. To display the cross section of mixing region of flows in our CDM, the biotin-streptavidin binding is detected through the fluorescence resonance energy transfer (FRET) pair of fluorescent proteins - R-phycoerythrin (RPE) and cross-linked allophycocyanin (clAPC). We expect the diagnosis technique using FRET will be successfully applied to biochemical analysis in microfluidic system.
RF-MEMS Switched Varactors for Medium Power Applications
Venue: arXiv cs.OH 2008
Year: 2008

In RF (Radio Frequency) domain, one of the limitations of using MEMS (Micro Electromechanical Systems) switching devices for medium power applications is RF power. Failure phenomena appear even for 500 mW. A design of MEMS switched capacitors with an enhanced topology is presented in this paper to prevent it. This kind of device and its promising performances will serve to fabricate a MEMS based phase shifter able to work under several watts.
Low-Drift Flow Sensor with Zero-Offset Thermopile-Based Power Feedback
Venue: arXiv cs.OH 2008
Year: 2008

A thermal flow sensor has been realised consisting of freely-suspended silicon-rich silicon-nitride microchannels with an integrated Al/poly-Si++ thermopile in combination with up- and downstream Al heater resistors. The inherently zero offset of the thermopile is exploited in a feedback loop controlling the dissipated power in the heater resistors, eliminating inevitable influences of resistance drift and mismatch of the thin-film metal resistors. The control system cancels the flow-induced temperature difference across the thermopile by controlling a power difference between both heater resistors, thereby giving a measure for the flow rate. The flow sensor was characterised for power difference versus water flow rates up to 1.5 ul/min, being in good agreement with a thermal model of the sensor, and the correct low-drift operation of the temperature-balancing control system has been verified.
Single Chip Sensing of Multiple Gas Flows
Venue: arXiv cs.OH 2008
Year: 2008

The fabrication and experimental characterization of a thermal flow meter, capable of detecting and measuring two independent gas flows with a single chip, is described. The device is based on a 4 x 4 mm2 silicon chip, where a series of differential micro-anemometers have been integrated together with standard electronic components by means of postprocessing techniques. The innovative aspect of the sensor is the use of a plastic adapter, thermally bonded to the chip, to convey the gas flow only to the areas where the sensors are located. The use of this inexpensive packaging procedure to include different sensing structures in distinct flow channels is demonstrated.
Comparison Between Damping Coefficients of Measured Perforated Micromechanical Test Structures and Compact Models
Venue: arXiv cs.OH 2008
Year: 2008

Measured damping coefficients of six different perforated micromechanical test structures are compared with damping coefficients given by published compact models. The motion of the perforated plates is almost translational, the surface shape is rectangular, and the perforation is uniform validating the assumptions made for compact models. In the structures, the perforation ratio varies from 24% - 59%. The study of the structure shows that the compressibility and inertia do not contribute to the damping at the frequencies used (130kHz - 220kHz). The damping coefficients given by all four compact models underestimate the measured damping coefficient by approximately 20%. The reasons for this underestimation are discussed by studying the various flow components in the models.
Model Based Sensor System for Temperature Measurement in R744 Air Conditioning Systems
Venue: arXiv cs.OH 2008
Year: 2008

The goal is the development of a novel principle for the temperature acquisition of refrigerants in CO2 air conditioning systems. The new approach is based on measuring the temperature inside a pressure sensor, which is also needed in the system. On the basis of simulative investigations of different mounting conditions functional relations between measured and medium temperature will be derived.
A Nanostructual Microwave Probe Used for Atomic Force Microscope
Venue: arXiv cs.OH 2008
Year: 2008

In order to develop a new structure microwave probe, the fabrication of AFM probe on the GaAs wafer was studied. A waveguide was introduced by evaporating Au film on the top and bottom surfaces of the GaAs AFM probe. A tip having 8 micrometers high, and curvature radius about 50 nm was formed. The dimensions of the cantilever are 250x30x15 micrometers. The open structure of the waveguide at the tip of the probe was introduced by using FIB fabrication. AFM topography of a grating sample was measured by using the fabricated GaAs microwave probe. The fabricated probe was found having nanometer scale resolution, and microwave emission was detected successfully at the tip of the probe by approaching Cr-V steel and Au wire samples.
Next Generation of TCAD Environments for MEMS Design
Venue: arXiv cs.OH 2008
Year: 2008

In this paper we present the latest version of the TCAD environment BICEP'S (Braunschweigs Integrated CAD-Environment for Product Planning and Process Simulation). By using a central process database, which allows the exchange of all relevant process data it is able to overcome many of the mentioned obstacles. The database and process planning tool can be used by process developers to document changes in process settings and the influence of such changes on the process result. This information can then be used by the designers to set-up a simulation file for a detailed analysis of the impact of such parameter changes on the requested design. This will be shown by the example of silicon etching using an atomistic etch simulator.
Haptic sensing for MEMS with application for cantilever and Casimir effect
Venue: arXiv cs.OH 2008
Year: 2008

This paper presents an implementation of the Cosserat theory into haptic sensing technologies for real-time simulation of microstructures. Cosserat theory is chosen instead of the classical theory of elasticity for a better representation of stress, especially in the nonlinear regime. The use of Cosserat theory leads to a reduction of the complexity of the modelling and thus increases its capability for real time simulation which is indispensable for haptic technologies. The incorporation of Cosserat theory into haptic sensing technology enables the designer to simulate in real-time the components in a virtual reality environment (VRE) which can enable virtual manufacturing and prototyping. The software tool created as a result of this methodology demonstrates the feasibility of the proposed model. As test demonstrators, a cantilever microbeam and microbridge undergoing bending in VRE are presented.
Modelling methodology of MEMS structures based on Cosserat theory
Venue: arXiv cs.OH 2008
Year: 2008

Modelling MEMS involves a variety of software tools that deal with the analysis of complex geometrical structures and the assessment of various interactions among different energy domains and components. Moreover, the MEMS market is growing very fast, but surprisingly, there is a paucity of modelling and simulation methodology for precise performance verification of MEMS products in the nonlinear regime. For that reason, an efficient and rapid modelling approach is proposed that meets the linear and nonlinear dynamic behaviour of MEMS systems.
High Quality Factor Silicon Cantilever Driven by PZT Actuator for Resonant Based Mass Detection
Venue: arXiv cs.OH 2008
Year: 2008

A high quality factor (Q-factor) piezoelectric lead zirconat titanate (PZT) actuated single crystal silicon cantilever was proposed in this paper for resonant based ultra-sensitive mass detection. Energy dissipation from intrinsic mechanical loss of the PZT film was successfully compressed by separating the PZT actuator from resonant structure. Excellent Q-factor, which is several times larger than conventional PZT cantilever, was achieved under both atmospheric pressure and reduced pressures. For a 30 micrometer-wide 100 micrometer-long cantilever, Q-factor was measured as high as 1113 and 7279 under the pressure of 101.2 KPa and 35 Pa, respectively. Moreover, it was found that high-mode vibration can be realized by the cantilever for the pursuit of great Q-factor, while support loss became significant because of the increased vibration amplitude at the actuation point. An optimized structure using node-point actuation was suggested then to suppress corresponding energy dissipation.
Flexible Micro Thermoelectric Generator based on Electroplated Bi2Te3
Venue: arXiv cs.OH 2008
Year: 2008

We present and discuss the fabrication process and the performance of a flexible micro thermoelectric generator with electroplated Bi2Te3 thermocouples in a SU-8 mold. Demonstrator devices generate 278uWcm-2 at dTmeas=40K across the experimental set up. Based on model calculations, a temperature difference of dTG=21.4K across the generator is assumed. Due to the flexible design and the chosen generator materials, the performance stays high even for curved contact surfaces. The measurement results correlate well with the model based design optimization predictions.
Package Hermeticity Testing with Thermal Transient Measurements
Venue: arXiv cs.OH 2008
Year: 2008

The rapid incursion of new technologies such as MEMS and smart sensor device manufacturing requires new tailor-made packaging designs. In many applications these devices are exposed to humid environments. Since the penetration of moisture into the package may result in internal corrosion or shift of the operating parameters, the reliability testing of hermetically sealed packages has become a crucial question in the semiconductor industry.
Open Ended Microwave Oven for Packaging
Venue: arXiv cs.OH 2008
Year: 2008

A novel open waveguide cavity resonator is presented for the combined variable frequency microwave curing of bumps, underfills and encapsulants, as well as the alignment of devices for fast flip-chip assembly, direct chip attach (DCA) or wafer-scale level packaging (WSLP). This technology achieves radio frequency (RF) curing of adhesives used in microelectronics, optoelectronics and medical devices with potential simultaneous micron-scale alignment accuracy and bonding of devices. In principle, the open oven cavity can be fitted directly onto a flip-chip or wafer scale bonder and, as such, will allow for the bonding of devices through localised heating thus reducing the risk to thermally sensitive devices. Variable frequency microwave (VFM) heating and curing of an idealised polymer load is numerically simulated using a multi-physics approach. Electro-magnetic fields within a novel open ended microwave oven developed for use in micro-electronics manufacturing applications are solved using a de icated Yee scheme finite-difference time-domain (FDTD) solver. Temperature distribution, degree of cure and thermal stresses are analysed using an Unstructured Finite Volume method (UFVM) multi-physics package. The polymer load was meshed for thermophysical analysis, whilst the microwave cavity - encompassing the polymer load - was meshed for microwave irradiation. The two solution domains are linked using a cross-mapping routine. The principle of heating using the evanescent fringing fields within the open-end of the cavity is demonstrated. A closed loop feedback routine is established allowing the temperature within a lossy sample to be controlled. A distribution of the temperature within the lossy sample is obtained by using a thermal imaging camera.
Mechanical Fatigue on Gold MEMS Devices: Experimental Results
Venue: arXiv cs.OH 2008
Year: 2008

The effect of mechanical fatigue on structural performances of gold devices is investigated. The pull-in voltage of special testing micro-systems is monitored during the cyclical load application. The mechanical collapse is identified as a dramatic loss of mechanical strength of the specimen. The fatigue limit is estimated through the stair-case method by means of the pull-in voltage measurements. Measurements are performed by means of the optical interferometric technique.
Correlated Anarchy in Overlapping Wireless Networks
Venue: arXiv cs.GT 2008
Year: 2008

We investigate the behavior of a large number of selfish users that are able to switch dynamically between multiple wireless access-points (possibly belonging to different standards) by introducing an iterated non-cooperative game. Users start out completely uneducated and naive but, by using a fixed set of strategies to process a broadcasted training signal, they quickly evolve and converge to an evolutionarily stable equilibrium. Then, in order to measure efficiency in this steady state, we adapt the notion of the price of anarchy to our setting and we obtain an explicit analytic estimate for it by using methods from statistical physics (namely the theory of replicas). Surprisingly, we find that the price of anarchy does not depend on the specifics of the wireless nodes (e.g. spectral efficiency) but only on the number of strategies per user and a particular combination of the number of nodes, the number of users and the size of the training signal. Finally, we map this game to the well-studied minority game, generalizing its analysis to an arbitrary number of choices.
On the Convergence Time of the Best Response Dynamics in Player-specific Congestion Games
Venue: arXiv cs.GT 2008
Year: 2008

We study the convergence time of the best response dynamics in player-specific singleton congestion games. It is well known that this dynamics can cycle, although from every state a short sequence of best responses to a Nash equilibrium exists. Thus, the random best response dynamics, which selects the next player to play a best response uniformly at random, terminates in a Nash equilibrium with probability one. In this paper, we are interested in the expected number of best responses until the random best response dynamics terminates. As a first step towards this goal, we consider games in which each player can choose between only two resources. These games have a natural representation as (multi-)graphs by identifying nodes with resources and edges with players. For the class of games that can be represented as trees, we show that the best-response dynamics cannot cycle and that it terminates after O(n^2) steps where n denotes the number of resources. For the class of games represented as cycles, we show that the best response dynamics can cycle. However, we also show that the random best response dynamics terminates after O(n^2) steps in expectation. Additionally, we conjecture that in general player-specific singleton congestion games there exists no polynomial upper bound on the expected number of steps until the random best response dynamics terminates. We support our conjecture by presenting a family of games for which simulations indicate a super-polynomial convergence time.
Throughput and Delay Analysis of Wireless Random Access Networks
Venue: arXiv cs.NI 2008
Year: 2008

This paper studies the network throughput and transport delay of a multihop wireless random access network based on a Markov renewal model of packet transportation. We show that the distribution of the source-to-destination (SD) distance plays a critical role in characterizing network performance. We establish necessary and sufficient condition on the SD distance for scalable network throughput, and address the optimal rate allocation issue with fairness and the QoS requirements taken into consideration. In respect to the end-to-end performance, the transport delay is explored in this paper along with network throughput. We characterize the transport delay by relating it to nodal queueing behavior and the SD-distance distribution; the former is a local property while the latter is a global property. In addition, we apply the large deviation theory to derive the tail distribution of transport delay. To put our theory into practical network operation, several traffic scaling laws are provided to demonstrate how network scalability can be achieved by localizing the traffic pattern, and a leaky bucket scheme at the network access is proposed for traffic shaping and flow control.