A competition-motivated capstone design course: the result of afifteen-year evolution

In this paper, a design course organization is presented, which is the result of 15 years of experience with a two-semester senior design course sequence in the Department of Electrical and Computer Engineering at the University of Detroit Mercy. An organization has been determined, which for the authors, balances team experience, individual assessment, design complexity, realism, writing content, and faculty workload. The current course structure is based on the integration of a capstone program with the Intelligent Ground Vehicle Competition (IGVC) sponsored by the Association For Unmanned Vehicle Systems International (AUVSI). The competition rules require that the students design and build an autonomous land vehicle which can navigate while sensing lane lines, avoiding obstacles, and traveling over ramps and sand traps. There are two main competition events: the vehicle performance competition where the autonomous robotic vehicles compete to finish the course in the shortest time or by traveling the farthest in the allotted time, and the vehicle design competition that evaluates the documentation, design process, and presentation of each team. The authors have found that this type of competition matches both the spirit and the practical needs of their capstone design course     

Design of a single-switch-per-phase converter for switchedreluctance motor drives

The main considerations in the design of a single-switch-per-phase converter for a switched reluctance motor (SRM) drive are described, with particular attention given to the choice of converter topology, the type of switching devices, the normalized rating of the power devices, and input filter design. The converter uses MOSFET switches. Experimental verification is included with a 6/4 pole personal-computer-controlled prototype SRM drive     

PHYSIOLOGICAL AND MORPHOLOGICAL CHANGES IN IMMOBILIZED L. PLANTARUM NCIM 2084 CELLS DURING REPEATED BATCH FERMENTATION FOR PRODUCTION OF LACTIC ACID

L. Plantarum NCIM 2084 cells are homofermentative, essentially producing lactic acid as the main end product of glucose fermentation. Prolonged use through repeated batch fermentation with the cells of L. plantarum immobilized on chitosan treated polypropylene matrix showed a shift in the metabolic pathway from the homofermentative to heterofermentative, accompanied by morphological changes in immobilized cells from the normal rod shape to the coccoid shape. These changes appear to be related to a shift in the bacterial cell metabolism, resulting in a decrease in lactic acid yields.     

Edge passivation and related electrical stability in silicon powerdevices

Factors governing long-term stability of silicon power devices are discussed with particular reference to a major failure mechanism observed in a thyristor device. The device failure was due to electrical instability during an electrical and thermal stability storage test, wherein it was observed that the reverse blocking voltage deteriorated under applied bias at the rated maximum junction temperature. The major cause of this failure was identified as lack of exhaust during the edge passivation and curing process due to which excessive chemical deposits are retained in the bevel region of the silicon element. This contributes to surface leakage current and, hence, a rapid degradation of the off-state characteristics. An orthogonal array experiment was employed to optimize the process factors and levels. The manufacturing process was then modified by incorporating an effective exhaust system in the passivant curing oven. This resulted in marked improvements in the electrical stability and manufacturing yield of this device     

Silver nanorods induced oxidative stress and chromosomal aberrations in the Allium cepa model

The production of different size and shape silver nanoparticles (AgNPs) has increased considerably in recent years due to several commercial and biological applications. Here, rod‐shaped AgNPs (SNRs) were prepared using the microwave‐assisted method and characterised by ultraviolet–visible spectroscopy, and transmission electron microscopy analysis. The present study aims to investigate the cyto–genotoxic effect of various concentrations (5, 10, and 15 µM) of SNRs using Allium cepa model. As a result, concentration‐dependent cyto–genotoxic effect of SNRs was observed through a decrease in the mitotic index, and an increase in the chromosomal aberrations such as chromosome break, disturbed metaphase, and anaphase bridge. To check the impact of Ag⁺ ions, 15 µM silver nitrate (AgNO₃) was prepared and tested in all the assays. Furthermore, cell viability and different reactive oxygen species assays were performed to test the cytotoxicity evaluation of SNRs. The authors found that in all the tested assays, SNRs at high concentrations (15 µM) and AgNO₃ (15 µM) were observed to cause maximal damage to the roots. Therefore, the current study implies that the cytotoxicity and genotoxicity of SNRs were dependent on the concentration of SNRs.Inspec keywords: ultraviolet spectra, biomedical materials, silver, cellular biophysics, nanorods, toxicology, visible spectra, nanoparticles, nanofabrication, transmission electron microscopy, nanomedicine, aberrations, microwave materials processingOther keywords: biological applications, rod‐shaped AgNPs, microwave‐assisted method, ultraviolet‐visible spectroscopy, transmission electron microscopy, chromosomal aberrations, chromosome break, silver nitrate, reactive oxygen species assays, cytotoxicity, genotoxicity, silver nanorods, oxidative stress, shape silver nanoparticles, concentration‐dependent cyto‐genotoxic effect, Allium cepa model, mitotic index, disturbed metaphase, anaphase bridge, cell viability, cytotoxicity evaluation, Ag     

Visualization research with large displays [analysis ofcommunication networks and services]

We describe our research at AT&T Infolab on using large displays to interactively analyze and visualize AT&T's communication networks and services     

The convexity of loss rate in an Erland loss system and sojourn inan Erlang delay system with respect to arrival and service rates

The Erlang loss system is a system in which customers arriving in a Poisson stream of arrival rate λ are served by a group of n servers, with a mean service time of 1/μ. Arrivals that find all servers busy are blocked and cleared from the system. The Erlang delay system is a system in which customers who find all servers busy wait in a queue until served by the first available server. Proofs of joint-convexity results in the Erlang delay system and Erlang loss system are presented, using induction on the number of servers and making use of the relation between the Erlang B and the Erlang C functions. The approach leads to a straightforward algebraic analysis of the properties of the performance measures of interest and avoids cumbersome manipulations     

Radiation grafting of hydrophilic monomers onto plasticized poly(vinyl chloride) sheets

Medical grade poly(vinyl chloride) (PVC) sheets were surface modified by grafting a combination of 2-hydroxyethyl methacrylate (HEMA) and N-vinyl pyrrolidone (NVP) or NVP alone using gamma radiation in an effort to retard the migration of the plasticizer from the PVC matrix. Presence of cupric ions at a concentration of 0.005m was found to be optimal in not only preventing the homopolymerization of the monomers but also producing the highest graft yield at all monomer concentrations used for grafting. The grafted PVC was characterized for its water absorption properties. Surface morphology of the grafted surface was examined using scanning electron microscopy (SEM). PVC sheets grafted on both sides as well as on one side were characterized for their physical and mechanical properties in order to assess their suitability in biomedical applications. While the tensile strength and percentage elongation values of PVC sheets grafted on both sides showed a downward trend with increasing graft yield, these properties were not drastically affected by surface modification on one side only at graft yields pertinent to prevent the migration of the plasticizer. Measurement of Shore A hardness and optical transparency of the migration resistant sheetings showed that such properties were not seriously affected by surface modification thus rendering them suitable for their intended applications.