Determining decay rates of polar cap plasma using bservations of polar cap patches

Polar cap patches are large scale structures occurring in the high-latitude ionosphere. They are regions of enhanced plasma density of at least twice the background density, and they are often observed in the polar cap region. The primary decay mechanism is via a two-step rearrangement and recombination reaction involving Oxygen and Nitrogen. Small scale structures within polar cap patches can result in scintillation of radio signals such as those used in Global Navigation Satellite Systems (GNSS). As such, quantifying the decay rate of the plasma is of importance if the effects on such communications are to be predicted. Observations were obtained during the Northern Deep Winter experiment, a series of incoherent scatter radar world days that took place in December 2014. Data from multiple incoherent scatter radars at high latitudes will be utilised to observe the same plasma at several locations as it is transported. From these observations, the decay of the plasma will be calculated and compared to the results of laboratory experiments

A study of the application of microwave techniques to the measurement of solid propellant burning rates Final report

Utilization of Doppler microwave interferometer for measuring solid propellant burning rate

Group and intergroup parameters of gang activities: An introduction and research agenda.

In introducing this Special Issue on gangs, we overview the thrust of its papers, demonstrating how they assist in plugging research gaps from the dearth of psychological attention to gangs. The papers therein raise important theoretical considerations of group process effects, social identity, and communication influences in gangs. Also included are empirical examinations of how attitudes to formal organized crime groups may nurture progang views, how social networks bridge gang divides, the dehumanization and social dominance association with gang membership, and how membership longevity associates with gang members’ attitudes to their group. We conclude with theoretical prospects and empirical vistas for future work. For instance, vitality theory may help explain members’ immersion in gangs, discursive strategies could explain how youth are enticed into gangs, and examinations of community and law enforcement attitudes to gangs may provide insight into how oppositional attitudes are fostered on both sides of the gang divide

Fabrication of PEM Fuel Cell Bipolar Plates by Indirect SLS

The paper presents a new manufacturing technique involving Selective Laser Sintering (SLS) for proton exchange membrane fuel cell (PEMFC) bipolar plate fabrication. A material system for bipolar plate fabrication was identified to satisfy both the cell performance requirement and SLS operation restriction. Carbonization and liquid epoxy infiltration are subsequently performed following the completion of SLS green bipolar plate. The finished SLS bipolar plate showed impressive surface finish and mechanical strength, and a single fuel cell was assembled with two SLS end plates and membrane electrode assembly (MEA) in between. Various physical property tests were performed with positive results. Fuel cell performance (voltage vs. current density, voltage vs. time, etc.) will be assessed in the near future.Mechanical Engineerin

Improvement of Electrical Conductivity of SLS PEM Fuel Cell Bipolar Plates

Previous work in this research demonstrated the feasibility of fabrication of proton exchange membrane (PEM) fuel cell bipolar plates by an indirect selective laser sintering (SLS) route. Properties of the SLS bipolar plate, such as flexural strength, corrosion resistance and gas impermeability, etc. are quite promising and satisfactory. However, initial results showed that there was still room for the improvement in electrical conductivity. This paper summaries the strategies investigated in an effort to increase the electrical conductivity, among which are: (1) infiltration of brown parts with conductive polymer (2) addition of a liquid phenolic infiltration/re-curing step prior to final sealing and (3) reduction of glassy carbon resistivity by curing process parameter control. Results show that the electrical conductivity value may be improved from 80 S/cm to around 108 S/cm, which is equivalent to a 35% jump, when the phenolic infiltration/re-curing step is applied before final epoxy sealing.Mechanical Engineerin

AIS Investigation of Agricultural Monocultures

Airborne Imaging Spectrometer (AIS) data were acquired over an agricultural area in eastern San Joaquin County, California in July, 1984. Cover type information was subsequently collected for all fields along this flight line. The lack of detailed ground data on individual fields, however, limited AIS data analysis to a qualitative comparison of the spectral reflectance curves for a total of nine cover types. Based on this analysis, it appears that cover types with a positive slope in the 1550 to 1700 nm region have a higher spectral response in the 1200 to 1300 nm region compared to those cover types with a negative slope in the 1550 to 1700 nm region. Within cover type, spectral variability was also found to be greater than that between cover types. Given the lack of additional field data, the reason for these differences is a matter of speculation

A New State Record for \u3ci\u3eOlixon Banksii\u3c/i\u3e (Hymenoptera: Rhopalosomatidae) in Missouri.

(excerpt) The cosmopolitan family Rhopalosmatidae is comprised of four genera and 37 species (Townes 1977, Goulet and Huber 1993, Fernandez and Sarmiento-M 2002, Lohrmann and Ohl 2007)

State Record for Stenamma foveolocephalum (Hymenoptera: Formicidae) in Missouri

We report the first known collection of Stenamma foveolocephalum (Hymenoptera: Formicidae) from Missouri. Two specimens were collected in pitfall traps during a field study at Sand Prairie Conservation Area, Scott County, Missouri