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Scalable nanolaminated SERS multiwell cell culture assay

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Microsystems & Nanoengineering 2020年第1期6卷 916-926页

作者： Xiang Ren Wonil Nam Parham Ghassemi Jeannine S.Strobl Inyoung Kim Wei Zhou Masoud Agah bradley department of electrical and computer engineering Virginia TechBlacksburgVA 24061USA department of Statistics Virginia TechBlacksburgVA 24061USA

This paper presents a new cell culture platform enabling label-free surface-enhanced Raman spectroscopy(SERS)analysis of biological *** platform integrates a multilayered metal-insulator-metal nanolaminated SERS substrate and polydimethylsiloxane(PDMS)multiwells for the simultaneous analysis of cultured *** cell lines,including breast normal and cancer cells and prostate cancer cells,were used to validate the applicability of this unique *** cell lines were cultured in different *** Raman spectra of over 100 cells from each cell line were collected and analyzed after 12h of introducing the cells to the *** unique Raman spectra of each cell line yielded biomarkers for identifying cancerous and normal cells.A kernel-based machine learning algorithm was used to extract the high-dimensional variables from the Raman ***,the nonnegative garrote on a kernel machine classifier is a hybrid approach with a mixed nonparametric model that considers the nonlinear relationships between the higher-dimension *** breast cancer cell lines and normal breast epithelial cells were distinguished with an accuracy close to 90%.The prediction rate between breast cancer cells and prostate cancer cells reached 94%.Four blind test groups were used to evaluate the prediction power of the SERS *** peak intensities at the selected Raman shifts of the testing groups were selected and compared with the training groups used in the machine learning *** blind testing groups were correctly predicted 100% of the time,demonstrating the applicability of the multiwell SERS array for analyzing cell populations for cancer research.

关键词： laminated culture prediction

Laser Machined Fiber‑Based Microprobe: Application in Microscale Electroporation

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Advanced Fiber Materials 2022年第4期4卷 859-872页

作者： Jongwoon Kim Yajun Zhao Shuo Yang Ziang Feng Anbo Wang Rafael V.Davalos Xiaoting Jia bradley department of electrical and computer engineering Virginia TechBlacksburgVA 24060USA department of Biomedical engineering and Mechanics Virginia TechBlacksburgVA 24061USA

Microscale electroporation devices are mostly restricted to in vitro experiments(i.e.,microchannel and microcapillary).Novel fiber-based microprobes enable in vivo microscale electroporation and arbitrarily select the cell groups of interest to *** developed a flexible,fiber-based microscale electroporation device through a thermal drawing process and femtosecond laser micromachining *** fiber consists of four copper electrodes(80μm),one microfluidic channel(30μm),and has an overall diameter of 400μ*** dimensions of the exposed electrodes and channel were customizable through a delicate femtosecond laser *** feasibility of the fiber probe was validated through numerical simulations and in vitro *** reversible and irreversible microscale electroporation was observed in a 3D collagen scaffold(seeded with U251 human glioma cells)using fluorescent *** ablation regions were estimated by performing the covariance error ellipse method and compared with the numerical *** computational and experimental results of the working fiber-based microprobe suggest the feasibility of in vivo microscale electroporation in space-sensitive areas,such as the deep brain.

关键词： Fiber probe Polymer Micromachine Irreversible electroporation Reversible electroporation Microscale electroporation

Unified optimal power flow model for AC/DC grids integrated with natural gas systems considering gas-supply uncertainties

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Journal of Modern Power Systems and Clean Energy 2018年第6期6卷 1193-1203页

作者： Jiale FAN Xiaoyang TONG Junbo ZHAO School of electrical engineering Southwest Jiaotong University bradley department of electrical and computer engineering Virginia Polytechnic Institute and State University

A unified optimal power flow(OPF) model for AC/DC grids integrated with natural gas systems is proposed for the real-time scheduling of power ***, the primary physical couplings underlying this coordinated system are modeled and investigated. In addition, the uncertainties of gas loads are considered when studying the role of gas supply for gas-fired units in power system operations. The nonlinear gas system constraints are converted to the second-order cone forms that allow for the use of the Benders decomposition techniques and the interior-point method to obtain the optimal solution. The numerical results of the modified IEEE 118-bus test system that integrates the Belgium 20-node natural gas system demonstrate the effectiveness of the proposed model. The effects of gas demand uncertainties on the optimal schedule of thermal generators are investigated as well.

关键词： AC/DC optimal power flow(OPF) Natural gas system Benders decomposition Second-order cone programming

Chip-scale gas chromatography:From injection through detection

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Microsystems & Nanoengineering 2015年第1期1卷 8-15页

作者： Muhammad Akbar Michael Restaino Masoud Agah VT MEMS Laboratory Bradley Department of Electrical and Computer EngineeringVirginia TechBlacksburgVA 24061USA department of Biomedical engineering and Mechanics Virginia TechBlacksburgVA 24061USA

Miniaturized gas chromatography(μGC)systems hold potential for the rapid analysis of volatile organic compounds(VOCs)in an extremely compact and low-power enabled ***,we utilize microfabrication technology to demonstrate the single chip integration of the key components of aμGC system in a two-step planar fabrication *** 1.5×3 cm microfluidic platform includes a sample injection unit,a micromachined semi-packed separation column(μSC)and a micro-helium discharge photoionization detector(μDPID).The sample injection unit consists of a T-shaped channel operated with an equally simple setup involving a single three-way fluidic valve,a micropump for sample loading and a carrier gas supply for subsequent analysis of the *** innovative sample injection technique described herein requires a loading time of only a few seconds and produces sharp and repeatable sample pulses(full width at half maximum of approximately 200 ms)at a carrier gas flow rate that is compatible with efficient chromatographic ***,our comprehensive characterization of the chip reveals that a wide variety of VOCs with boiling points in the range of 110–216℃ can be analyzed in less than 1 min by optimizing the flow and temperature programming ***,the analysis of four VOCs at the concentration level of one part per million in an aqueous sample(which corresponds to a headspace concentration in the lower parts-per-billion regime)was performed with a sampling time of only 6 *** μDPID has demonstrated a linear dynamic range over three orders of *** system presented here could potentially be used to monitor hazardous VOCs in real time in industrial workplaces and residential settings.

关键词： gas chromatography lab-on-a-chip MEMS microsystem

Guest Editorial: Advances in High Voltage DC Systems/Grids Control, Operation, and Protection

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High Voltage 2020年第5期5卷 499-500页

作者： Kumars Rouzbehi Ali Mehrizi-Sani department of Systems engineering and Automatic Control University of SevilleSpain. bradley department of electrical and computer engineering Virginia TechUSA.

Interconnections between AC power systems,power transmission with higher efficiency,and aggregation and delivery of power from offshore wind farms to different AC regions are among the main drivers for the development of HVDC *** grids can result in lower demand variability,higher flexibility,superior electricity market management,and higher economic *** is expected that isolated HVDC systems transition to an HVDC grid that overlays the existing AC *** a substantial development also results in a number of critical technical challenges related to system control,operation,and protection,which should be properly and accurately *** Special Issue focuses on the recent achievements and advancements in overcoming these *** papers for publications in this Special Issue fall into four major topics:devices,control,operation,and protection.

关键词： properly operation offshore

Detecting incentivized review groups with co-review graph

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High-Confidence Computing 2021年第1期1卷 35-44页

作者： Yubao Zhang Shuai Hao Haining Wang department of electrical and computer engineering University of DelawareNewarkDE 19716USA department of computer Science Old Dominion UniversityNorfolkVA 23529USA bradley department of electrical and computer engineering Virginia TechArlingtonVA 22203 USA

Online reviews play a crucial role in the ecosystem of nowadays business(especially e-commerce platforms),and have become the primary source of consumer *** manipulate consumers’opinions,some sellers of e-commerce platforms outsource opinion spamming with incentives(e.g.,free products)in exchange for incen-tivized *** incentives,by nature,are likely to drive more biased reviews or even fake *** e-commerce platforms such as Amazon have taken initiatives to squash the incentivized review practice,sellers turn to various social networking platforms(e.g.,Facebook)to outsource the incentivized *** aggre-gation of sellers who request incentivized reviews and reviewers who seek incentives forms incentivized review *** this paper,we focus on the incentivized review groups in e-commerce *** perform the data collections from various social networking platforms,including Facebook,WeChat,and Douban.A measurement study of incentivized review groups is conducted with regards to group members,group activities,and *** identify the incentivized review groups,we propose a new detection approach based on co-review ***,we employ the community detection method to find the suspicious communities from co-review *** also build a“gold standard”dataset from the data we collected,which contains the information of reviewers who belong to incentivized review *** utilize the“gold standard”dataset to evaluate the effectiveness of our detection approach.

关键词： Incentivized review groups Co-review graph Community detection

Anisotropic edge enhancement in optical scanning holography with spiral phase filtering

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Chinese Optics Letters 2016年第1期14卷 21-25页

作者： Kelly K. Dobson 贾伟 Ting-Chung Poon bradley department of electrical and computer engineering Virginia TechBlacksburgVA 24061USA Lab of Information Optics and Optoelectronic technology Shanghai Institute of Optics and Fine MechanicsChinese Academy of SciencesShanghai 201800China

Anisotropic edge enhancement is simulated using a spiral phase plate （SPP） in optical scanning holography （OSH）. We propose to use a delta function and an SPP as the pupil functions to realize anisotropic edge enhancement. The interference of these two pupils is used to two-dimensionally scan an object to record its edge-only information. This is done in three ways： first, by shifting the SPP, second, by using two offset SPPs of same charge, and finally, by using two oppositely charged SPPs. Our computer simulations show the capability of selectively enhancing the edges of a given obiect.

关键词： Delta functions Electron holography Holography Scanning Surface plasmon resonance

PD measurements,failure analysis,and control in high-power IGBT modules

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High Voltage 2018年第3期3卷 170-178页

作者： Mona Ghassemi department of electrical and computer engineering Virginia Polytechnic Institute and State University(Virginia Tech)BlacksburgVA 24061USA

Increased voltage blocking capability and the development of packaging technology for IGBTs can enhance the local electric field that may become large enough to increase partial discharges(PDs)within the *** study presents a survey on(i)simulation the electric field within an IGBT module;(ii)current standards for evaluation of the insulation systems of IGBTs;(iii)PD detection and localisation methods as well as other diagnostic and quality control test methods about IGBTs;and(iv)various methods for PD control in an IGBT *** survey shows remarkable technical gaps in all four *** sophisticated numerical and theoretical techniques are needed to model complicated geometries,*** sharp edges of the copper metallisation and protrusions in the substrate,and composite non-linear field grading *** is no model to take into account defects in the gel and on the ceramic *** 61287-1 cannot sufficiently assess the behaviour of PDs on IGBT module under the actual operating conditions exposing fast rise pulse-width modulation-like *** is no agreement on the exact origin and location of PDs in the module with relying on measured phase-resolved PD *** control methods using non-linear grading materials are not mature enough.

关键词： enough insulation ceramic

An enhanced method for fast generation of hologram sub-lines

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Chinese Optics Letters 2009年第12期7卷 1092-1096页

作者： P. W. M. Tsang J. P. Liu K. W. K. Cheung T.-C. Poon department of Electronic engineering City University of Hong Kong Tat Chee Avenue Kowloon Hong Kong SAR China department of Photonics Feng Chia University No. 100 Wenhwa Rd. Seatwen Taichung 40724 China bradley department of electrical and computer engineering Virginia Tech Blacksburg Virginia 24061 USA

Sub-lines are one-dimensional diffraction patterns representing the light beams emerging from horizontal planes of an object image. Past research has demonstrated that the sub-lines can be encapsulated as a multi-bank filtering process, and implemented with a field programmable gate array （FPGA） device. As the complexity of the filters is high, their length and the number of input pins have to be reduced substantially, hence leading to degradation on the reconstructed images. We propose an enhanced method to overcome the problem by binarizing the filters＇ coefficients, and half-toning the pixel intensities of the object image. Experimental evaluation reveals that our method results in reconstructed images are superior to that obtained with the parent method.

关键词： Diffraction Field programmable gate arrays (FPGA) Holographic interferometry