12,508 research outputs found
Complete gradient-LC-ESI system on a chip for protein analysis
This paper presents the first fully integrated gradient-elution liquid chromatography-electrospray ionization (LC-ESI) system on a chip. This chip integrates a pair of high-pressure gradient pumps, a sample injection pump, a passive mixer, a packed separation column, and an ESI nozzle. We also present the successful on-chip separation of protein digests by reverse phase (RP)-LC coupled with on-line mass spectrometer (MS) analysis
Simulation of valveless micropump and mode analysis
In this work, a 3-D simulation is performed to study for the solid-fluid
coupling effect driven by piezoelectric materials and utilizes asymmetric
obstacles to control the flow direction. The result of simulation is also
verified. For a micropump, it is crucial to find the optimal working frequency
which produce maximum net flow rate. The PZT plate vibrates under the first
mode, which is symmetric. Adjusting the working frequency, the maximum flow
rate can be obtained. For the micrpump we studied, the optimal working
frequency is 3.2K Hz. At higher working frequency, say 20K Hz, the fluid-solid
membrane may come out a intermediate mode, which is different from the first
mode and the second mode. It is observed that the center of the mode drifts.
Meanwhile, the result shows that a phase shift lagging when the excitation
force exists in the vibration response. Finally, at even higher working
frequency, say 30K Hz, a second vibration mode is observed.Comment: Submitted on behalf of EDA Publishing Association
(http://irevues.inist.fr/EDA-Publishing
Optimal Mechanical Design with Robust Performance by Fuzzy Formulation Strategy
[[abstract]]This paper presents an optimum design methodology for obtaining the highest robust performance using fuzzy multi-objective formulation strategy. The target performance and its variation, as functions of normally distributed variables with stochastic independence, are simultaneously minimized in this design process. A functional representation of the variability of the performance and the computational algorithm of the robust design process are presented in the paper. Two categories of design problems are examined: (1) the robust design with expected target of minimal variation. (2) The robust design with optimized target of minimal variation. The strength-based reliability behaves as the design objective that was merged in the formulation to extend the application of the proposed method. Three mechanical design examples further illustrate the presented integrated design methodology and successfully show its advantage.[[notice]]補æ£å®Œç•¢[[incitationindex]]E
Level-cut approaches of first and second kind for unique solution design in fuzzy engineering optimization problems
[[abstract]]Two single level-cut approaches of the first and second kind for obtaining the unique compromise design in solving nonlinear optimum engineering design problems with fuzzy resources have been developed and presented in this paper. The conventional standard level-cuts method has been discussed for inspiring the proposed novel formulation consequently. The proposed strategies with the illustrative design examples indicate that the unique design as well as corresponding optimum level-cut value can be guaranteed obtained. Additionally, two wide-applicable linear or nonlinear membership functions of objective functions are presented depending on the practical situations of design tasks. The proposed level-cut approaches have been shown easy formulation and successfully employed to large-scaled structural design problems by sequential quadratic programming (SQP) technique combined with the finite element analysis.[[notice]]補æ£å®Œç•¢[[journaltype]]國內[[incitationindex]]E
Multiobjective fuzzy optimization with random variables in a mix of fuzzy and probabilistic environment
[[abstract]]The fuzzy λ-formulation is used to solve multiobjective optimization problems in which the design variables are random, the constraints as a whole has a fuzzy probability or the constraints are mixed of deterministic, stochastic and fuzzy constraints. The fuzzy optimization strategy helps one to get the highest degree of satisfaction in reaching an optimum solution. The idea of expected value and the chance constrained programming technique allows one to convert a stochastic optimization problem into its equal deterministic form. The design of a three-bar truss illustrates the proposed design optimization in detail and the design of a machine-tool spindle express the comprehensive work of this technique. Results show that the proposed formulation and method can generate a natural, well-behaved, and reliable design[[conferencetype]]國際[[conferencedate]]19950320~19950324[[iscallforpapers]]Y[[conferencelocation]]Yokohama, Japa
Batalin-Vilkovisky Integrals in Finite Dimensions
The Batalin-Vilkovisky method (BV) is the most powerful method to analyze
functional integrals with (infinite-dimensional) gauge symmetries presently
known. It has been invented to fix gauges associated with symmetries that do
not close off-shell. Homological Perturbation Theory is introduced and used to
develop the integration theory behind BV and to describe the BV quantization of
a Lagrangian system with symmetries. Localization (illustrated in terms of
Duistermaat-Heckman localization) as well as anomalous symmetries are discussed
in the framework of BV.Comment: 35 page
Decision Analysis on Water Resources Planning and Management for an Arid Metropolitan Center in West Texas
The demand by consumers for public-owned low-priced natural resources is essentially insatiable. When natural resources become scarce the public is agonized by the problem of making an optimum choice or choices from feasible alternatives, preferably from a large number of feasible alternatives. In order to determine the best solutions in terms of satisfying constrained requirements, systematic procedures must be adopted for resources planning and management processes.
The Need for a Comprehensive Systems Approach to Urban Water Resources Planning
In the past, management and planning programs for water resources have been based primarily on one attribute--money. Sharp criticism has been directed to this type of single-minded planning approach as exemplified in the following speech by Senator Stephen Youngs[38],
For a large segment of our water resources program, both the Executive Branch and Congress now scrutinize each project as though it were a narrow commercial undertaking. We concentrate attention on those direct prospective benefits which are strictly measurable in dollars and cents such as the dollar value of property saved from floods, or the amount by which river navigation saves freight charges. We then compare these narrowly construed monetary benefits to cost. In almost every instance, the benefits, human and social values, and vital objectives of national policy which cannot be measured in direct monetary terms often receive only supplementary attention, or none at all.
It has become the policy, as stated by Clayton[11], of the National Water Commission, that water resource projects should not be evaluated merely on a pure benefit-cost ratio, but that intangible benefits should also be considered. This prevailing attitude has catalyzed the application of decision analysis embedded with multiattribute characteristics for water resources development decision-making procedures.
Decision analysis is a systematic solution procedure which can be used to crystalize a complicated decision problem into manageable subproblems by ranking the decision alternatives in accordance with cardinal values attached to their consequences based on the principles outlines in utility theory. Recent advances in multiattribute utility theory allow the decision maker to assess utilities over intangible benefits such as social acceptance or recreation potential.
The relative importance of both intangible and tangible benefits such as cost or quality will all be weighted accordingly in the total utility evaluation. In this manner, the intangible benefits will receive due consideration in the final decision making process
New high-efficiency source of photon pairs for engineering quantum entanglement
We have constructed an efficient source of photon pairs using a
waveguide-type nonlinear device and performed a two-photon interference
experiment with an unbalanced Michelson interferometer. Parametric
down-converted photons from the nonlinear device are detected by two detectors
located at the output ports of the interferometer. Because the interferometer
is constructed with two optical paths of different length, photons from the
shorter path arrive at the detector earlier than those from the longer path. We
find that the difference of arrival time and the time window of the coincidence
counter are important parameters which determine the boundary between the
classical and quantum regime. When the time window of the coincidence counter
is smaller than the arrival time difference, fringes of high visibility
(80 10%) were observed. This result is only explained by quantum theory
and is clear evidence for quantum entanglement of the interferometer's optical
paths.Comment: 4 pages, 4 figures, IQEC200
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