MEASUREMENT OF PLANAR FAULT PROBABILITIES IN AUSTEMPERED DUCTILE IRON AND 304L STAINLESS STEEL

During plastic deformation both stacking and twin faults can be generated in face-centered cubic materials, including iron-based metals that contain thermally stable austenite. These planar faults are a critical component of the austenite to martensite transformation, forming shear bands that can act as nucleation sites. The measurement of these faults via x-ray diffraction has been long established, however it has not been applied widely to austempered ductile irons. The ability to measure these faulting probabilities could give insights into the transformation as a function of deformation. In this work both planar fault densities were measured in austempered ductile iron to test the feasibility of the x-ray diffraction peak-shift (stacking) and centroid-shift (twin) techniques in these materials using a traditional laboratory diffractometer and synchrotron beamline source. Experimentation was also performed with 304L stainless steel as a baseline material for comparison. The errors associated with this technique are also discussed and highlighted. Errors in the laboratory diffractometer measurement were shown to be significant and therefore the experimental setup should be carefully considered when performing these types of analyses

Fixed effects estimation of the intensive and extensive margins of irrigation water demand

Irrigation water demand is estimated using field-level panel data from Kansas over 16 years. The cost of pumping varies over time due to changes in energy prices and across space due to differences in the depth to water. Exploiting this variation allows us to estimate the demand elasticity while controlling for field-farmer and year fixed effects. Fixed effects also allow us to control for land use without an instrument or assumptions about the distribution of errors. Our estimates of water demand are used to calculate the cost of reducing irrigation water use through water pricing, irrigation cessation, and intensity-reduction programs

Optimization algorithms for loading military diesel generators

The economic load dispatch (ELD) problem challenges the designer to adequately provide for electrical load demand while minimizing operational costs. The military has a unique set of constraints for meeting the ELD problem to provide power to soldiers in forward operating bases. The constraints include the use of military diesel gensets that remain disconnected from each other and are loaded below a user-defined real power threshold (for a reliability safety cushion). In addition, the system must be simple enough to be constructed with minimal training and require no reconfiguration once established. As a result, a simple tool to quickly assign loads to isolated military diesel generators is required. To meet this need, this study compares the use of several optimization algorithms including particle swarm optimization (PSO), bat algorithm (BA), cuckoo search (CS), first fit decreasing (FFD) bin packing, and an exhaustive search (ES) method. It is found that at large enough search spaces, the optimization algorithms can discover reasonably optimal solutions while substantially decreasing search time. For this application, FFD has more optimal average solutions as well as faster run time compared to the other algorithms

Phylogenetic Patterns in Montane Troglodytes Wrens

Phylogenetic studies based on mitochondrial DNA sequences of 10 species of wrens in Troglodytes and related genera suggest a new hypothesis of relationships for the group. The Winter Wren (T. troglodytes) and the anomalous Timberline Wren (Thryorchilus browni) are distantly related to the remainder of Troglodytes. The latter group divides into a tropical montane group and a northern/lowland group that includes the northernmost two montane taxa (T. rufociliatus, T. brunneicollis). Erection of the genus Nannus for the Winter Wren is proposed. Song evolution in the complex has involved either convergent derivation or retention of primitive song types in distant lineages

Exercise-Induced Anaphylaxis: A Case Report and Review of the Diagnosis and Treatment of a Rare but Potentially Life-Threatening Syndrome

A 24-year-old male Marine with an uncomplicated medical history and a long history of strenuous, daily exercise presented to the emergency department after experiencing anaphylactic shock while running. Symptoms resolved following administration of intramuscular diphenhydramine, ranitidine, intravenous methylprednisolone, and intravenous fluids. On followup in the allergy clinic, a meticulous clinical history was obtained which elucidated a picture consistent with exercise-induced anaphylaxis. He had experienced diffuse pruritus and urticaria while exercising on multiple occasions over the last three years. His symptoms would usually increase as exercise continued. Prior to the first episode, he regularly exercised without symptoms. Exercise-induced anaphylaxis is a rare but potentially life-threatening syndrome that requires a careful clinical history and is a diagnosis of exclusion. Treatment is primarily exercise avoidance. Prophylactic mediations are inconsistently effective but are empirically used. Successful treatment with omalizumab was recently reported in a case of refractory exercise-induced anaphylaxis

The Effects of Pre-Workout Meals High in Carbohydrates or Lipids on Muscle Fatigue during Resistance Exercise: A Pilot Study

Purpose: Pre-workout nutrition is important in exercise training and is often overlooked or misunderstood. The purpose of this study was to examine the effects of pre-workout meals high in carbohydrates or lipids on muscular endurance in lower body muscles and fatigue during a back squat exercise in physically active college students. Methods: All subjects (n = 8) reported to the lab 2 times, with 24-48 hours of rest between sessions. Subjects’ height, weight, and blood pressure were taken before each session. Subjects were led through a dynamic warm-up consisting of foam rolling, dynamic stretching, and barbell back squat warm-ups every session. Session one was for estimation of subjects’ back squat 1-repetition maximum (1RM) using a PUSH-Strength accelerometer-based velocity tool. During the second session, participants were instructed to consume a carbohydrate or lipid bar and wait 45 minutes for digestion. Subjects then completed the warm-up and performed one back squat set to failure using 75% of their predicted 1RM. Results: The carbohydrate group performed more repetitions and lifted for a longer time than the lipid group (p \u3c 0.05). Conclusion: Our data suggest that a carbohydrate-heavy meal immediately prior is beneficial to maximize muscular endurance in resistance training

Testing of Wideband Small Satellite Receivers in Complex Radio Frequency Environments Using Synthetic Spectrum Generation Techniques

As spacecraft technology improves, smaller cost-effective spacecraft become capable of increasingly sophisticated Earth observation missions, including wideband Radio Frequency (RF) sensing. Current methods available for validating the RF payloads on-board these missions, such as on-orbit payload validation using a pathfinder mission, are expensive, time consuming, and difficult. The challenge of modelling the RF environment of an orbital receiver is increased by path characteristics that become nontrivial at orbital velocities and distances, as well as unique modelling challenges such as ionospheric delay and multiple transmitters. A fast, inexpensive method for validating RF sensing payloads on the ground is presented in this paper. This method makes use of custom-made synthetic spectrum generation software, where the transmitter-receiver system is modelled in high fidelity and digital signal processing tools are used to simulate the RF environment at the orbital receiver. This modelling is performed using a set of modules to simulate factors affecting signals received by the spacecraft. Path loss, Doppler shift, and other channel-effect modules are used to create a realistic RF environment at the receiver. Representative networks of transmitters are simulated in this system, with nodes adhering to rules defined in network modules. Modules can be added to alter the overall transmitter network, receiver, and path models as required. To perform end-to-end payload testing, a Software Defined Radio transmitter generates representative RF spectrum, which is injected into the payload under test either over the air or via cable. Testing components along the RF chain is accomplished by modelling components up the chain, then injecting synthetic RF spectrum at the component of interest. The test system presented in this paper can also simulate the data output of Software Defined Radio payload receivers, such that data analysis methods and software processes can be validated without requiring access to physical payload components. End users of orbital RE spectrum can simulate scenarios to determine what data will be most useful to them, and modelling the RF stages up to the analog-to-digital converter ensures representative inputs for signal processing validation. The ability to accurately, quickly and cost-effectively test RF payloads at the component level or end-to-end makes this system a powerful tool for small satellite developers