Bricklayer: An Authentic Introduction to the Functional Programming Language SML

Functional programming languages are seen by many as instrumental to effectively utilizing the computational power of multi-core platforms. As a result, there is growing interest to introduce functional programming and functional thinking as early as possible within the computer science curriculum. Bricklayer is an API, written in SML, that provides a set of abstractions for creating LEGO artifacts which can be viewed using LEGO Digital Designer. The goal of Bricklayer is to create a problem space (i.e., a set of LEGO artifacts) that is accessible and engaging to programmers (especially novice programmers) while providing an authentic introduction to the functional programming language SML.Comment: In Proceedings TFPIE 2014, arXiv:1412.473

Red Onion Mountain Maximum Security Prison − A Case Study in Ground Improvement

The Red Onion Mountain project involved the construction of a high security prison facility in a remote area of southwest Virginia. The site of the proposed construction was covered with a thick layer of uncontrolled mine spoil fill material containing a random matrix of soil and boulders. This material was unsuitable for the proposed construction in its existing condition. Charged with evaluating feasible and cost effective alternatives for site development and structural support, the project\u27s geotechnical engineers devised a two-phase ground improvement plan designed to adequately improve the existing mine spoil fill. Full-time observation, documentation and testing during the site preparation phase provided data that was used to evaluate the effectiveness of the ground improvement procedures. Building construction proceeded on the improved soils after an evaluation of the data indicated the existing mine spoil had been adequately improved

Design and Testing of a Prosthetic Foot Prototype With Interchangeable Custom Rotational Springs to Adjust Ankle Stiffness for Evaluating Lower Leg Trajectory Error, an Optimization Metric for Prosthetic Feet

A prosthetic foot prototype intended for evaluating a novel design objective for passive prosthetic feet, the Lower Leg Trajectory Error (LLTE), is presented. This metric enables the optimization of prosthetic feet by modeling the trajectory of the lower leg segment throughout a step for a given prosthetic foot and selecting design variables to minimize the error between this trajectory and target physiological lower leg kinematics. Thus far, previous work on the LLTE has mainly focused on optimizing conceptual foot architectures. To further study this metric, extensive clinical testing on prototypes optimized using this method has to be performed. Initial prototypes replicating the LLTE-optimal designs in previous work were optimized and built, but at 1.3 to 2.1 kg they proved too heavy and bulky to be considered for testing. A new, fully-characterized foot design reducing the weight of the final prototype while enabling ankle stiffness to be varied is presented and optimized for LLTE. The novel merits of this foot are that it can replicate a similar quasi-stiffness and range of motion of a physiological ankle, and be tested with variable ankle stiffnesses to test their effect on LLTE. The foot consists of a rotational ankle joint with interchangeable U-shaped constant stiffness springs ranging from 1.5 Nm/deg to 16 Nm/deg, a rigid structure extending 0.093 m from the ankle-knee axis, and a cantilever beam forefoot with a bending stiffness of 16 Nm2. The prototype was built using machined acetal resin for the rigid structure, custom nylon springs for the ankle, and a nylon beam forefoot. In preliminary testing, this design performed as predicted and its modularity allowed us to rapidly change the springs to vary the ankle stiffness of the foot. Qualitative feedback from preliminary testing showed that this design is ready to be used in larger-scale studies. In future work, extensive clinical studies with testing different ankle stiffnesses will be conducted to validate the optimization method using the LLTE as a design objective.Massachusetts Institute of Technology. Tata Center for Technology and DesignMassachusetts Institute of Technology. Department of Mechanical Engineerin

Slow growth, stress response and aging in Saccharomyces cerevisiae

The unicellular organism Saccharomyces cerevisiae was used as a modelsystem to study aging at the cellular level. It is known that limiting the amount of calories used by cells can lead to an extension of lifespan. This thesis shows that by applying controlled slow growth circumstances, cells increase their stress response. Besides the increased stress response, also the substance nicotinamide seems to be involved in facilitating the elongation of lifespan by influencing genetic stability. Limiting the food supply apparently leads to an enhanced agility of the yeast cells. An adequate stress response is essential for cells to survive harsh environmental circumstances. However, the investment in these mechanisms of defence requires resources, which are limited. Cell cycle synchronised cells were analysed for their stress response during the cell cycle. It was found that there were differences on translational and transcriptional level for stress genes during the cell cycle. The effect on the translational response could be due to low protein synthesis rates during the G1-phase. Old and young yeast cells were also compared to each other with respect to their stress response and survival capabilities. It turned out that old cells show a lower stress response than young cells and that after induction by hydrogen peroxide this does not increase much. However, no significant effects were observed on survival, which is rather strange but could be due to insensitivity of the assay. The defence against oxygen radicals can possibly be reinforced by exogenously adding antioxidants. To find potent new antioxidants a screening method was developed using a thioredoxin promoter construct. It was shown that vitamin E and glutathione were able to decrease the reportergene indicating a lowered oxidative stress level

Design and Testing of a Low-Cost and Low-Maintenance Drip Irrigation Filtration System for Micro-Irrigation in Developing Countries

The cylindrical filters presently used in <1000 m2 drip irrigation systems are frequently clogged, increasing pressure loss and lowering the flow rate through the filters. This work investigates the mechanisms for this clogging and proposes an alternative filtration design that would enable both more reliable and lower maintenance filtering. This proposed system is compatible with existing drip irrigation systems and could be made inexpensively with plastic bottle manufacturing equipment. To compare the proposed design to off-the-shelf options, a drip irrigation test setup was built to measure the pressure loss across different filters as particles accumulated. These experiments confirmed that pleated cartridge filters, with high effective surface area, incurred lower pressure losses than cylindrical filters. These tests revealed that the greatest reason for clogged performance was that filtered particles (not the cartridge filter itself) eventually restricted the flow of water through the system. This inspired the redesign of the filter housing such that the housing extended far below the filter, providing a catch basin away from the filter for the particles to settle. Fixing the filter independently of the bottom casing significantly improved the overall performance of the filtration system, reduced the maintenance requirement necessary from the user, and would enable inexpensive manufacturing via blow molding. This paper experimentally demonstrates that the cartridge filter inside the redesigned housing can filter out over 2 kg of sand while maintaining less than a .03 bar pressure drop across the filter at a flow rate of 25 l/s.Massachusetts Institute of Technology. Tata Center for Technology and DesignMassachusetts Institute of Technology. Department of Mechanical Engineerin

Delivering a low-cost, reliable drip irrigation filtration system for micro-irrigation in developing countries

The cylindrical filters presently used in drip irrigation systems frequently clog, increasing pressure loss and lowering the flow rate through the filters. This work investigates alternative filtration strategies that increase the reliability of, and are compatible with, existing systems. To test different filtration strategies, a drip irrigation test setup was built to measure the pressure loss across different filters as particles accumulated. These experiments found that pleated cartridge filters, with high effective surface area, incurred the lowest pressure losses. More significantly, it was observed during these tests that the filtered out particles settled to the bottom of the filter housing when flow through the filter ceased. This inspired the redesign of the filter housing such that the housing extended far below the filter, providing a catch basin away from the filter for the particles to settle. Fixing the filter independently of the bottom casing significantly improves the overall performance of the filtration system and can be inexpensively manufactured via blow molding. This paper experimentally demonstrates that the cartridge filter inside the redesigned housing can filter out over 2 kg of sand while maintaining less than a .03 bar pressure drop across the filter at a flow rate of 25 l/s.MIT Tata Center for Technology and DesignMassachusetts Institute of Technology. Department of Mechanical EngineeringInternational Development Enterprise

The Tyranny of the Vital Few: The Pareto Principle in Language Design

Modern high-level programming languages often contain constructs whose semantics are non-trivial. In practice how- ever, software developers generally restrict the use of such constructs to settings in which their semantics is simple (programmers use language constructs in ways they understand and can reason about). As a result, when developing tools for analyzing and manipulating software, a disproportionate amount of effort ends up being spent developing capabilities needed to analyze constructs in settings that are infrequently used. This paper takes the position that such distinctions between theory and practice are an important measure o f the analyzability of a language

Elegant software for investigation of electron transport systems

Abstract: this paper presents the possibilities of the software elegant for the investigation of electron transport systems. The research object is the electron accelerator Photo-CATCH. It is used to study electron sources that a later further examined by the electron accelerator S-DALINAC (Superconducting-Darmstadt-LINear-Accelerator). For the installation of a new cryogenic electron source, which is expected to extend the lifetime of the CsO-coating, the setup needed to be rearranged to be able to use the existing source as well as the new cryogenic source with one beamline. The characteristics of the beam properties of both sources were obtained using elegant. After executing all necessary simulations and analysing the results, the beamline could be readjusted, and the source put into operation

Feasibility of a Clutchless Dual-Shaft Hybrid Transmission System for Performance Applications

A novel hybrid-electric transmission concept was sought that yields higher acceleration and smoother gear-shifts compared to existing dual-clutch systems while improving the energy efficiency of the vehicle. After evaluating a range of strategies, the elimination of the clutch was identified as a viable method for reducing the vehicle's effective inertia and viscous losses. The proposed architecture implements a single electric motor, and two separate shafts for odd and even gears, to replace the functions of a clutch. High acceleration rates can be achieved using the electric motor when launching the vehicle. Furthermore, the torque from the electric motor (EM) and internal combustion engine (ICE) can be simultaneously delivered through the two shafts to sustain this high acceleration. A 0 to 100 km/hr time of 3.18 s was simulated for a 1600 kg vehicle using a 180 kW EM and 425 kW ICE. In addition, the EM can be used to match the speeds of consecutive gears on the two shafts to reduce jerk while shifting. Shift durations were found to vary between 0.2 and 0.9 s using this strategy. Other benefits include regenerative braking and the removal of the reverse gear since the EM can rotate in either direction. It was also found that the vehicle can be operated on only electric power in urban settings - represented by the NEDC driving cycle - if the battery is recharged through regenerative braking, and by the ICE the vehicle is stopped.Massachusetts Institute of Technology. Tata Center for Technology and Desig