Atlas and checklist of the bark and ambrosia beetles of Texas and Oklahoma (Curculionidae: Scolytinae and Platypodinae)

180 species of bark and ambrosia beetles (Curculionidae: Scolytinae and Platypodinae) are known to occur in Texas and Oklahoma. 175 species are known from Texas, 35 of which are reported here for the first time. 78 species are known from Oklahoma, 47 of which are new records for the state. Based on overall distribution patterns the largest group of species found in Texas and virtually all known from Oklahoma are widely distributed in eastern and southeastern North America, reaching their southwestern limits here. In the case of Texas other large elements include Neotropical elements shared with Mexico and a large number found in southwestern North America. New distribution and significant new host records are discussed. Distribution maps are included for most species and a checklist is provided as an appendix

Control of perennial weeds based on weed biology and environmental considerations

Timing, type and duration of tillage operations and cropping practices are of importance for reducing the regeneration of perennial weeds and also for minimizing the environmental impacts of such operations. In the present work and with reference to previous publications we find that, based on the knowledge gained on growth patterns, sensitivity to competition, growth potential of roots and mechanical and management measures it is possible to coordinate control of perennial weeds with considerations of yield and reduced environmental impact

A note on leapfrogging vortex rings

In this paper we provide examples, by numerical simulation using the Navier-Stokes equations for axisymmetric laminar flow, of the 'leapfrogging' motion of two, initially identical, vortex rings which share a common axis of symmetry. We show that the number of clear passes that each ring makes through the other increases with Reynolds number, and that as long as the configuration remains stable the two rings ultimately merge to form a single vortex ring

Development of a low-cost, electricity-generating Rankine cycle, alcohol-fuelled cooking stove for rural communities

This article describes a novel design and construction of a helical tube flash boiler that uses a 2kW nominal methylated spirit burner to heat an approximately 2.5m long coil of copper pipe fed by a nominal 8 bar electrically operated solenoid water pump. The final embodiment is for superheated steam to be converted to electricity and the waste exit heat from the generator used either for cooking or for ethanol pro duction for low-income families in developing countries. The performance of the flash boiler has been evaluated experimentally based on the well-known “Direct-Method”; by carefully measuring both the flow of the fuel and the steam. It found that the pressure inside the pipe can reach up to 7.4 bar and the temperature of the steam released by the flashing process can reach 255°C utilising a low-cost water pump. The research results prese nted in this paper demonstrate that flash boiler stove has a great potential for generating high-temperature steam for developing a low-cost cooking stove

Relationships between soil moisture-holding properties and soil texture, organic matter content, and bulk density

Specimens from the surface horizon and the subsoil of 62 soil horizons in Hedmark and Oppland were investigated to study how the mechanical composition of the soil, the organic matter content and the bulk density affect their porosity and air capacity and their total and available water content. Most of the specimens belonged to the loam group, and a smaller number was from sandy and silty types of soil. Equations were established to make it possible to calculate the water retention curves and the amount of available water from the above mentioned parameters. As a rule, errors derived from the equations are no greater than those which are found in similar research in other countries

The Influence of Heat Input Ratio on Electrical Power Output of a Dual-Core Travelling-Wave Thermoacoustic Engine

This paper presents an analytical and experimental investigation of an electricity generator that employs a two-stage looped tube travellin -wave thermoacoustic prime-mover to deliver acoustic power from heat energy, a loudspeaker to extract electricity from sound energy and a tuning stub to compensate the changes in the acoustic field within the engine to enable close to travelling wave operation at the loudspeaker. Furthermore, the paper explains how to enhance the output power utilizing different heat input ratios through the engine cores. A well-known thermoacoustic design tool called Delta EC is used to simulate the wave propagation through the different parts of the system. The electrical power predicted from the low-cost prototype was 24.4 W acoustic power which confirms the potential for developing low-cost thermoacoustic electricity generator for heat recov ery from low-grade heat sources. The electrical power can be increased to 31.3 W using different heating power percentages through the two units. The verified experimental data shows good agreement with DeltaEC results

Suspension Design, Modeling, and Testing of a Thermo-Acoustic-Driven Linear Alternator

The Score-Stove™ generates electricity from a wood-burning cooking stove using a thermo-acoustic engine (TAE) that converts heat to sound through a linear alternator (LA). This paper introduces a prototype hemitoroidal suspension that was refined into a segmented trapezoidal shape that gave a higher cyclic life for the LA and includes a critical evaluation that compares a theoretical analysis with experimental results. The results show an improvement from the 40% efficiency of a standard loudspeaker used in reverse as an LA to 70–80% efficiency with the new suspension and a double Halbach array magnetic topology

Low-speed Wind-Tunnel Study of Reaction Control-jet Effectiveness for Hover and Transition of a STOVL Fighter Concept

A brief wind-tunnel study was conducted in the Langley 12-Foot Low-Speed Tunnel to determine reaction control-jet effectiveness and some associated aerodynamic characteristics of a 15 percent scale model of the General Dynamics E-7A STOVL fighter/attack aircraft concept applicable to hover and transition flight. Tests were made with the model at various attitude angles in the tunnel test section and at various tunnel airspeeds for a range of control-jet nozzle pressure ratios. Eight reaction control-jets were tested individually. Four jets were at the design baseline locations providing roll, pitch, and yaw control. Comparisons of measured data with values calculated using empirical methods were made where possible