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2008

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Articles 1651 - 1680 of 4190

Full-Text Articles in Engineering

Predicting The Hydrogen Pressure To Achieve Ultralow Friction And Diamondlike Carbon Surfaces From First Principles, Haibo Guo, Yue Qi, Xiaodong Li Jun 2008

Predicting The Hydrogen Pressure To Achieve Ultralow Friction And Diamondlike Carbon Surfaces From First Principles, Haibo Guo, Yue Qi, Xiaodong Li

Faculty Publications

Hydrogen atmosphere can significantly change the tribological behavior at diamond and diamondlike carbon (DLC) surfaces and the friction-reducing effect depends on the partial pressure of hydrogen. We combined density functional theory modeling and thermodynamic quantities to predict the equilibrium partial pressures of hydrogen at temperature T, PH2 (T), for a fully atomic hydrogen passivated diamondsurface. Above the equilibrium PH2 (T), ultralow friction can be achieved at diamond and DLC surfaces. The calculation agrees well with friction tests at various testing conditions. We also show that PH2 (T) …

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Microwave Signal Generation Using Self-Heterodyning Of A Fast Wavelength Switching Sg-Dbr Laser, Michael A. Bernacil, Shame O' Connor, Ben Maher, Andew Dekelaita, Dennis J. Derickson Jun 2008

Microwave Signal Generation Using Self-Heterodyning Of A Fast Wavelength Switching Sg-Dbr Laser, Michael A. Bernacil, Shame O' Connor, Ben Maher, Andew Dekelaita, Dennis J. Derickson

Electrical Engineering

Microwave signal generation using self-heterodyning of a single wavelength tunable SG-DBR laser is demonstrated. Microwave signals are established by quickly hopping back and forth between two optical wavelengths. These wavelengths are made time coincident through a delay line interferometer. The output of the interferometer is photodetected resulting in a CW microwave signal. This method does not require conventional master-slave laser configurations, external microwave drive sources, or a mode locked laser used to beat dual longitudinal modes. Microwave signals up to 12 GHz have been measured by frequency modulating the phase section of the SG-DBR laser with low frequency RF square …

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Using Factor Analysis To Assess Route Construction Priority For Common Duct Network In Taiwan, Wei Tong Chen, Tung-Tsan Chen, Yung Pei Lin, Chien Lu Jun 2008

Using Factor Analysis To Assess Route Construction Priority For Common Duct Network In Taiwan, Wei Tong Chen, Tung-Tsan Chen, Yung Pei Lin, Chien Lu

Journal of Marine Science and Technology–Taiwan

This study identifies the critical variables for determining route construction priorities (RCP) in a common duct network (CDN) using expert interviews and questionnaire surveys. Statistical analysis is also conducted to check the validation and verification of the survey results. Furthermore, factor analysis is employed to derive 24 priority determinant variables and classify them into five groups, including utility agency, traffic condition, local government, infrastructure project, and site condition. The paired comparison method is then employed to determine the weightings of the five groups. It is found that the utility agency is the most important factor while the site condition is …

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Enhancement Of Shg In Fused Sio2 By Corona Poling Under Water, Water Vapor And Salty Environments, Chun-An Tsai, Jung Ning Wang, Wei-Kuo Chao, Tsung Yuan Cheng, Wan-Rone Liou, Adam Y. Wu Jun 2008

Enhancement Of Shg In Fused Sio2 By Corona Poling Under Water, Water Vapor And Salty Environments, Chun-An Tsai, Jung Ning Wang, Wei-Kuo Chao, Tsung Yuan Cheng, Wan-Rone Liou, Adam Y. Wu

Journal of Marine Science and Technology–Taiwan

We found that optical nonlinearity in SiO2 glass sample can be greatly enhanced when sample is poled in wet and salty environments, and the nonlinearity in the sample can be reduced drastically when sample is washed in water. Possible causes for the observed enhancement and reduction of optical nonlinearity in SiO2 glass are discussed.

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Service Quality Radar Map And Two-Stage Service Quality Score, Kee-Kuo Chen, Ding-Hsun Hsiao, Cheng-Hung Arthur Hsieh Jun 2008

Service Quality Radar Map And Two-Stage Service Quality Score, Kee-Kuo Chen, Ding-Hsun Hsiao, Cheng-Hung Arthur Hsieh

Journal of Marine Science and Technology–Taiwan

In an attempt to portray all information released from the service quality studies the service quality radar map (SQRM), is designed in this paper firstly and a generalized service quality score GSQS follows. GSQS is defined by way of the weighted average of differences between relative frequencies of customers’ performance perception and performance expectation, thus can avoid the problems involved in the gap-based SERVQUAL scale and caused by skewed distributions. A special case of GSQS, the stochastic dominance service quality score (SDSQS) whose ideal come from the second stochastic dominance criterion is used to illustrate how a standardized score can …

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Optimization Of Diffuser Valves, Chin-Tsan Wang, Pi-Cheng Chang, Chien-Cheng Huang Jun 2008

Optimization Of Diffuser Valves, Chin-Tsan Wang, Pi-Cheng Chang, Chien-Cheng Huang

Journal of Marine Science and Technology–Taiwan

In this study, the width of channel, D, and diffuser angle, , at given diffuser width whose value is 100 m will be studied for steady and unsteady flow conditions. By means of a series of numerical simulations, some findings for diffuser valve will be reported. The diffuser valve with a channel width of D = 300 m and diffuser angle =60º, is a better geometry because of its outstanding capability on suction production of net volume flow. Besides, the larger the Reynolds number is, the greater the suction amount of net volume flow will be. When the aspect ratio …

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Cpt-Based Liquefaction Assessment By Using Fuzzy-Neural Network, Shuh-Gi Chern, Ching-Yinn Lee, Chin-Chen Wang Jun 2008

Cpt-Based Liquefaction Assessment By Using Fuzzy-Neural Network, Shuh-Gi Chern, Ching-Yinn Lee, Chin-Chen Wang

Journal of Marine Science and Technology–Taiwan

Because of the increasing popularity worldwide of the cone penetration test (CPT) for site characterization, significant progress on the simplified CPT-based methods has been made for evaluation of earthquake induced liquefaction potential of soils. In this study, a fuzzy-neural network combined with 466 CPT field observations is developed to evaluate liquefaction potential of soils. The proposed model combines fuzzy theory with subtractive clustering algorithm to establish a fuzzy-neural system. The study indicates that fuzzy-neural network can successfully describe the complex relationship between seismic parameters, soil parameters, and the liquefaction potential. The fuzzy-neural network model is found to have very good …

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Investigation On The Blast Resistance Of A Stiffened Door Structure, Ming-Wei Hsieh, Jui-Pin Hung, De-Jen Chen Jun 2008

Investigation On The Blast Resistance Of A Stiffened Door Structure, Ming-Wei Hsieh, Jui-Pin Hung, De-Jen Chen

Journal of Marine Science and Technology–Taiwan

This study was aimed at investigating the blast resistance of a stiffened door structure. For this, a series of finite element transient analysis were performed to predict the dynamic response of blast resistant doors. Current results show that the stiffeners have sustained the majority of the explosive loadings. The effect of stiffener size on the stress state was rated in terms of the ratio of stiffener stress to plate stress, which was enhanced with the increase of web thickness of stiffener. Additional, the highest stresses were shown to occur at the transverse stiffeners near the hinged sides with a maximum …

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A Surveillance System To Create And Distribute Geo-Referenced Mosaics Using Suav Video, Evan D. Andersen Jun 2008

A Surveillance System To Create And Distribute Geo-Referenced Mosaics Using Suav Video, Evan D. Andersen

Theses and Dissertations

Small Unmanned Aerial Vehicles (SUAVs) are an attractive choice for many surveillance tasks. However, video from an SUAV can be difficult to use in its raw form. In addition, the limitations inherent in the SUAV platform inhibit the distribution of video to remote users. To solve the problems with using SUAV video, we propose a system to automatically create geo-referenced mosiacs of video frames. We also present three novel techniques we have developed to improve ortho-rectification and geo-location accuracy of the mosaics. The most successful of these techniques is able to reduce geo-location error by a factor of 15 with …

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Sulphur-Tolerant Anode For Solid Oxide Fuel Cell, David J. Bayless, Jason P. Trembly Jun 2008

Sulphur-Tolerant Anode For Solid Oxide Fuel Cell, David J. Bayless, Jason P. Trembly

Mechanical and Aerospace Engineering Faculty Research & Creative Works

An anode for a solid oxide fuel cell. The anode is not harmed by sulfur-containing compounds, nor is its resistance increased thereby. The anode has two layers, including a “protective” layer (A) and a layer (B) that oxidizes molecular hydrogen The protective layer has a diffusion rate for molecular hydrogen that exceeds its diffusion rate for sulfur-containing compounds, and has an oxidation rate for sulfur-containing compounds that exceeds its oxidation rate for molecular hydrogen. The first anode layer can be selected fro the group of Lanthanum Strontium Titanate (LST) and Lanthanum Strontium Vanadate (LSV), and the second anode layer is …

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The Effect Of Radiation On The Electrical Properties Of Aluminum Gallium Nitride/Gallium Nitride Heterostructures, John W. Mcclory Jun 2008

The Effect Of Radiation On The Electrical Properties Of Aluminum Gallium Nitride/Gallium Nitride Heterostructures, John W. Mcclory

Theses and Dissertations

AlGaN/GaN Heterojunction Field Effect Transistors (HFETs) were irradiated at low temperature and the temperature dependent changes to drain current, gate current, capacitance, and transconductance were measured. The results were compared to the charge control model of the drain current and trap-assisted tunneling model of the gate current to determine the source of the radiation-induced changes. AlGaN/GaN HFETs demonstrated threshold voltage shifts and drain current changes after irradiation. After electron and neutron irradiation applied at ~80 K, measurement of the drain current at this temperature showed an increase that saturated after 1013 electrons/cm2 or 1010 neutrons/cm2 due …

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An Optimization-Based Framework For Designing Robust Cam-Based Constant-Force Compliant Mechanisms, John Christian Meaders Jun 2008

An Optimization-Based Framework For Designing Robust Cam-Based Constant-Force Compliant Mechanisms, John Christian Meaders

Theses and Dissertations

Constant-force mechanisms are mechanical devices that provide a near-constant output force over a prescribed deflection range. This thesis develops various optimization-based methods for designing robust constant-force mechanisms. The configuration of the mechanisms that are the focus of this research comprises a cam and a compliant spring fixed at one end while making contact with the cam at the other end. This configuration has proven to be an innovative solution in several applications because of its simplicity in manufacturing and operation. In this work, several methods are introduced to design these mechanisms, and reduce the sensitivity of these mechanisms to manufacturing …

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Dpm Dispersion Study Using Cfd For Underground Metal / Nonmetal Mines, Yi Zheng, Jerry C. Tien Jun 2008

Dpm Dispersion Study Using Cfd For Underground Metal / Nonmetal Mines, Yi Zheng, Jerry C. Tien

Mining Engineering Faculty Research & Creative Works

Diesel Particulate Matter (DPM) is considered carcinogenic after prolonged exposure. With increasing use of diesel-powered mining equipment in underground mines, miner's exposure to DPM has been increasing. Most studies on the issue has been DPM control measures with few studies on diesel exhaust propagation patterns after leaving the tailpipes. This study uses computational fluid dynamics (CFD) to investigate the airflow pattern in an underground metal/nonmetal mine for a single heading. Several high DPM concentration areas are identified in the study and common practices for compliance are suggested. Airflow and DPM distribution are compared between blowing and exhausting face ventilation systems. …

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Significance Of Logic Synthesis In Fpga-Based Design Of Image And Signal Processing Systems, Mariusz Rawski, Henry Selvaraj, Bogdan J. Falkowski, Tadeusz Luba Jun 2008

Significance Of Logic Synthesis In Fpga-Based Design Of Image And Signal Processing Systems, Mariusz Rawski, Henry Selvaraj, Bogdan J. Falkowski, Tadeusz Luba

Electrical & Computer Engineering Faculty Research

This chapter, taking FIR filters as an example, presents the discussion on efficiency of different implementation methodologies of DSP algorithms targeting modern FPGA architectures. Nowadays, programmable technology provides the possibility to implement digital systems with the use of specialized embedded DSP blocks. However, this technology gives the designer the possibility to increase efficiency of designed systems by exploitation of parallelisms of implemented algorithms. Moreover, it is possible to apply special techniques, such as distributed arithmetic (DA). Since in this approach, general-purpose multipliers are replaced by combinational LUT blocks, it is possible to construct digital filters of very high performance. Additionally, …

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Intimate Partner Violence, Supervisor Support And Work Outcomes For Low-Wage Workers, Nanette Lucia Yragui Jun 2008

Intimate Partner Violence, Supervisor Support And Work Outcomes For Low-Wage Workers, Nanette Lucia Yragui

Dissertations and Theses

The workplace is a setting where women in abusive relationships can potentially access information and support to resolve the violence in their lives. This study addresses a critical need for data-based knowledge about how supervisors can effectively support employees experiencing intimate partner violence. The dissertation study examines supervisor support congruency (i.e., the match between support wanted and received) and work outcomes for Latina and non-Latina, abused women. Specifically, I examine which supervisor support measures best predict work outcomes for abused, low-wage, employees. In addition, I evaluate the criterion validity and reliability of a behavioral measure of wanted and received supervisor …

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Ceas E-News 06.10.2008, College Of Engineering And Applied Sciences Jun 2008

Ceas E-News 06.10.2008, College Of Engineering And Applied Sciences

College of Engineering and Applied Sciences News

Serving hotdogs and jobs at the 2nd Annual Co-op Cookout

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Sample Analysis Methodology Utilizngelectromagnetic Radation, John A. Woollam, Corey L. Bungay, Thomas E. Tiwald, Martin M. Liphardt, Ronald A. Synowicki, Gregory K. Pribil, Craig M. Herzinger, Blaine D. Johs, James N. Hilfiker Jun 2008

Sample Analysis Methodology Utilizngelectromagnetic Radation, John A. Woollam, Corey L. Bungay, Thomas E. Tiwald, Martin M. Liphardt, Ronald A. Synowicki, Gregory K. Pribil, Craig M. Herzinger, Blaine D. Johs, James N. Hilfiker

Department of Electrical and Computer Engineering: Faculty Publications

Simultaneous use of wavelengths in at least two ranges Selected from RADIO, MICRO. FIR, IR, NIR-VIS-NUV. UV, DUV, VUV EUV, XRAY in a regression procedure to evaluate parameters in mathematical dispersion structures to model dielectric functions.

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A Secure And Efficient Communications Architecture For Global Information Grid Users Via Cooperating Space Assets, Victor P. Hubenko Jr. Jun 2008

A Secure And Efficient Communications Architecture For Global Information Grid Users Via Cooperating Space Assets, Victor P. Hubenko Jr.

Theses and Dissertations

With the Information Age in full and rapid development, users expect to have global, seamless, ubiquitous, secure, and efficient communications capable of providing access to real-time applications and collaboration. The United States Department of Defense’s (DoD) Network-Centric Enterprise Services initiative, along with the notion of pushing the “power to the edge,” aims to provide end-users with maximum situational awareness, a comprehensive view of the battlespace, all within a secure networking environment. Building from previous AFIT research efforts, this research developed a novel security framework architecture to address the lack of efficient and scalable secure multicasting in the low earth orbit …

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Sample Analysis Methodology Utilizing Electromagnetic Radiation, John A. Woollam, Corey L. Bungay, Thomas E. Tiwald, Martin M. Liphardt, Ronald A. Synowicki, Gregory K. Pribil, Craig M. Herzinger, Blaine D. Johs, James N. Hilfiker Jun 2008

Sample Analysis Methodology Utilizing Electromagnetic Radiation, John A. Woollam, Corey L. Bungay, Thomas E. Tiwald, Martin M. Liphardt, Ronald A. Synowicki, Gregory K. Pribil, Craig M. Herzinger, Blaine D. Johs, James N. Hilfiker

Department of Electrical and Computer Engineering: Faculty Publications

Simultaneous use of wavelengths in at least two ranges selected from RADIO, MICRO, FIR, IR, NIR-VIS-NUV, UV, DUV, VUV, EUV, XRAY in a regression procedure to evaluate parameters in mathematical dispersion structures to model dielectric functions.

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Protein Interactions With Mixed Poly(Ethylene Glycol)/Polyacrylic Acid Brushes, Zhenqing Li Jun 2008

Protein Interactions With Mixed Poly(Ethylene Glycol)/Polyacrylic Acid Brushes, Zhenqing Li

All Theses

Tethered polymer chains that are grafted to a solid substrate by one chain end (polymer brushes) may be distinguished from other anchored polymer layers by the relatively high grafting densities gained. Potential uses of polymer brushes for interfacial modification to regulate interactions between proteins and substrates, such as drug delivery and protein separation, are widely recognized. Therefore, it is important to investigate interactions between proteins and surfaces modified with a polymer brush.
In this study, the 'grafting-to' method has been used to graft mixed poly(ethylene glycol) (PEG) and polyacrylic acid (PAA) brushes onto poly(glycidyl methacrylate) (PGMA)-modified silicon wafers/glass slides to …

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Laser-Induced Fluorescence And Performance Analysis Of The Ultra-Compact Combustor, Patrick J. Lakusta Jun 2008

Laser-Induced Fluorescence And Performance Analysis Of The Ultra-Compact Combustor, Patrick J. Lakusta

Theses and Dissertations

The AFIT Combustion Optimization and Analysis Laser (COAL) lab’s modular design and state-of-the-art diagnostic systems make it a flexible and important facility for the analysis of combustion processes. The objectives of the current research are to install several enhancements in the lab, validate the laser diagnostic system, characterize the igniter for AFIT’s Ultra-Compact Combustor (UCC) sections, and perform a non-intrusive laser diagnostic, performance, and high-speed video analysis of a flat-cavity UCC section. Validation of the laser system was accomplished using OH Planar Laser-Induced Fluorescence (PLIF) in a laminar hydrogen-air flame produced by a Hencken burner. Results are compared to previous …

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Statistical Methods For Image Registration And Denoising, Matthew D. Sambora Jun 2008

Statistical Methods For Image Registration And Denoising, Matthew D. Sambora

Theses and Dissertations

This dissertation describes research into image processing techniques that enhance military operational and support activities. The research extends existing work on image registration by introducing a novel method that exploits local correlations to improve the performance of projection-based image registration algorithms. The dissertation also extends the bounds on image registration performance for both projection-based and full-frame image registration algorithms and extends the Barankin bound from the one-dimensional case to the problem of two-dimensional image registration. It is demonstrated that in some instances, the Cramer-Rao lower bound is an overly-optimistic predictor of image registration performance and that under some conditions, the …

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Arliss-M Design Guide Version 1.1, Robert J. Twiggs Jun 2008

Arliss-M Design Guide Version 1.1, Robert J. Twiggs

Robert "Bob" Twiggs STEM Education Collection

A design guide for the ARLISS-M published on June 9, 2008.

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Fluorescence Tomography Characterization For Sub-Surface Imaging With Protoporphyrin Ix, Dax Kepshire, Scott C. Davis, Hamid Dehghani, Keith D. Paulsen, Brian W. Pogue Jun 2008

Fluorescence Tomography Characterization For Sub-Surface Imaging With Protoporphyrin Ix, Dax Kepshire, Scott C. Davis, Hamid Dehghani, Keith D. Paulsen, Brian W. Pogue

Dartmouth Scholarship

Optical imaging of fluorescent objects embedded in a tissue simulating medium was characterized using non-contact based approaches to fluorescence remittance imaging (FRI) and sub-surface fluorescence diffuse optical tomography (FDOT). Using Protoporphyrin IX as a fluorescent agent, experiments were performed on tissue phantoms comprised of typical in-vivo tumor to normal tissue contrast ratios, ranging from 3.5:1 up to 10:1. It was found that tomographic imaging was able to recover interior inclusions with high contrast relative to the background; however, simple planar fluorescence imaging provided a superior contrast to noise ratio. Overall, FRI performed optimally when the object was located on or …

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An Fpga Design Space Exploration Tool For Matrix Inversion Architectures, A. Irturk, B. Benson, S. Mirzaei, R. Kastner Jun 2008

An Fpga Design Space Exploration Tool For Matrix Inversion Architectures, A. Irturk, B. Benson, S. Mirzaei, R. Kastner

Electrical Engineering

Matrix inversion is a common function found in many algorithms used in wireless communication systems. As FPGAs become an increasingly attractive platform for wireless communication, it is important to understand the tradeoffs in designing a matrix inversion core on an FPGA. This paper describes a matrix inversion core generator tool, GUSTO, that we developed to ease the design space exploration across different matrix inversion architectures. GUSTO is the first tool of its kind to provide automatic generation of a variety of general purpose matrix inversion architectures with different parameterization options. GUSTO also provides an optimized application specific architecture with an …

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An Analysis Of Botnet Vulnerabilities, Sean W. Hudson Jun 2008

An Analysis Of Botnet Vulnerabilities, Sean W. Hudson

Theses and Dissertations

Botnets are a significant threat to computer networks and data stored on networked computers. The ability to inhibit communication between servers controlling the botnet and individual hosts would be an effective countermeasure. The objective of this research was to find vulnerabilities in Unreal IRCd that could be used to shut down the server. Analysis revealed that Unreal IRCd is a very mature and stable IRC server and no significant vulnerabilities were found. While this research does not eliminate the possibility that a critical vulnerability is present in the Unreal IRCd software, none were identified during this effort.

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A Selective Recovery Methodology For The Primary Purification Of Lipid Envelope Virus-Like Particles From S. Cerevisiae, Gaik Sui Kee, Hari Pujar, Nigel Titchener-Hooker Jun 2008

A Selective Recovery Methodology For The Primary Purification Of Lipid Envelope Virus-Like Particles From S. Cerevisiae, Gaik Sui Kee, Hari Pujar, Nigel Titchener-Hooker

Vaccine Technology II

No abstract provided.

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Well-Characterized Adenoviral Vector-Based Vaccines: Are We There Yet?, Katey Einterz Owen Jun 2008

Well-Characterized Adenoviral Vector-Based Vaccines: Are We There Yet?, Katey Einterz Owen

Vaccine Technology II

No abstract provided.

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Vaccine Development For Developing Countries – Regulatory Approach In The European Union, Manfred G. Haase Jun 2008

Vaccine Development For Developing Countries – Regulatory Approach In The European Union, Manfred G. Haase

Vaccine Technology II

No abstract provided.

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Analytical And Manufacturing Challenges In Preparation Of Bacterial Polysaccharide Conjugates, Carl Frasch Jun 2008

Analytical And Manufacturing Challenges In Preparation Of Bacterial Polysaccharide Conjugates, Carl Frasch

Vaccine Technology II

No abstract provided.

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