A comprehensive optimization methodology for strategic environmental sensor station locations

textAdverse weather poses a significant threat to transportation safety. Road weather information systems (RWIS) aim to mitigate the impact of adverse weather by detecting spatiotemporal variations of weather and/or road pavement conditions in real time. Due to the lack of a detailed, unified guideline and diverse weather conditions across the United States, state and city transportation agencies follow different practices for choosing locations for environmental sensor stations (ESS) (the components that collect RWIS weather data). To fill this gap, this study proposes a comprehensive cell-based methodology that is data-driven, using crash records, weather data, and road network information. The contribution of the proposed methodology is that the model optimizes overall benefits derived from RWIS based on weather-sensitive crashes. Both normal and adverse weather crash data are used to derive cell-vulnerability rates in adverse weather. First, a sequential procedure is devised to identify the required number of stations for the region. Then, optimal weather station locations are identified using a genetic algorithm. The proposed approach is especially suited for optimizing region-wide ESS locations involving complex road networks or a large number of road segments. A case study was conducted using data from the Crash Records Information System (CRIS) between 2010 and 2013 in the Austin District, an area especially vulnerable to rain. It was found in the case study that ten ESSs would be a good choice to implement in the region. Their proposed global optimal locations layout would cover 94% of total crashes occurring in the region based on 20 miles of coverage for each station. The RWIS would have spatial coverage of 48% and 92% reliability should one ESS fail.Civil, Architectural, and Environmental Engineerin

Coupling geomechanics with flow and tracer transport in complex fracture networks

Hydraulic fracturing in horizontal wells has enabled economic production from ultra-low permeability reservoirs. The productivity of these hydraulically fractured wells depends on the fracture dimensions, conductivity, connectivity to the wellbore, and applied drawdown pressure. Traditional numerical simulation models used to analyze the productivity of hydraulically fractured wells assume a planar bi-wing fracture that is open and connected to the wellbore. However, several core-through field studies and fracture propagation models have demonstrated that a hydraulic fracturing process can create non-planar complex fracture networks. The conductivity and connectivity of these complex fractures are highly dependent on the in-situ stress changes due to production. Hence it is critical to consider complex fractures and the impact of geomechanics in the simulation models for analyzing fractured well productivity. A finite-volume method based geomechanics coupled reservoir model was developed to simulate production from complex fracture networks. An automated meshing method was developed to create the reservoir, and fracture mesh for any given arbitrarily shaped fracture network. The reservoir-fracture network model accounts for fracture closure effects during production. The model developed in this dissertation was used to investigate the impact of drawdown strategy (choke management) on the productivity of wells producing from complex fracture networks. The competing phenomenon of higher initial production rate and faster fracture closure depending on the applied drawdown strategy was observed. Based on NPV maximization, an optimum drawdown strategy can be calculated. The model was also applied to estimate the effective permeability of the SRV (stimulated reservoir volume) to account for complex fractures in upscaled traditional reservoir simulation models. Tracer transport was implemented in the geomechanical reservoir simulation model to analyze the impact of (a) fracture geometry, (b) fracture propagation and closure effects, and (c) fracture complexity on the tracer response curves. An effective model was created to simulate tracer tests in complex fracture networks. Closure of activated natural fractures can explain the multiple peaks in the tracer response curves observed in the field tests. A neural network-based inverse modeling was performed to estimate effective connected fracture length using peak tracer concentration values, peak times, and tracer recovery from chemical tracer flowback data. Observations from the chemical tracer analysis were combined with radioactive proppant tracer and pressure interference tests to diagnose well interference for the Hydraulic Fracturing Test Site #1Petroleum and Geosystems Engineerin

Dislocations as channels for the fabrication of sub-surface porous GaN by electrochemical etching

Porosification of nitride semiconductors provides a new paradigm for advanced engineering of the properties of optoelectronic materials. Electrochemical etching creates porosity in doped layers whilst leaving undoped layers undamaged, allowing the realisation of complex three-dimensional porous nanostructures, potentially offering a wide range of functionalities, such as in distributed Bragg reflectors. Porous/non-porous multilayers can be formed by etching whole, as-grown wafers uniformly in one simple process, without any additional processing steps. The etch penetrates from the top down, through the undoped layers, leaving them almost untouched. Here, atomic-resolution electron microscopy is used to show that the etchant accesses the doped layers via nanometre-scale channels that form at dislocation cores and transport the etchant and etch products to and from the doped layer respectively. Results on AlGaN and non-polar GaN multilayers indicate the same mechanism is operating, suggesting this approach may be applicable in a range of materials

Posterior dislocation of the elbow as an unusual presentation after a total hip replacement: a case report

<p>Abstract</p> <p>Introduction</p> <p>Posterior dislocation of the elbow is usually associated with trauma to the joint with a reported incidence of 3%to 6%. Chronic instability is usually symptomatic following the initial injury.</p> <p>Case presentation</p> <p>We report a case of posterior dislocation of the elbow occurring in a patient while using her arm to lift herself using a monkey pole on the second day following a total hip replacement. The dislocation was reduced under sedation in the ward. There were no signs or symptoms suggesting any joint hypermobility syndrome in the patient. Follow up 4 months following the injury revealed a complete recovery in the range of motion and a pain free elbow. There were no signs and symptoms of any instability.</p> <p>Conclusion</p> <p>This is the first time such a case is reported in the literature. It certainly demonstrates that even in the absence of instability a patient can be predisposed to low energy dislocation of the elbow.</p

The Yellow Revolution in Malwa : alternative arenas of struggle and the cultural politics of development

Thesis (Ph. D. in History, Anthropology, and Science, Technology and Society (HASTS))--Massachusetts Institute of Technology, Program in Science, Technology and Society, 2009.Includes bibliographical references (p. 319-331).This dissertation engages with two analytical frameworks to explore questions of social transformation and structures of power in rural society in India. The first is a specific critique of various types of development discourse and development projects that have been elaborated by national and international elites during the last forty years, focusing on the dry land Malwa region in the central Indian state of Madhya Pradesh. This includes a project to introduce soyabean cultivation to the region in the 1970s, which has been post-facto labeled as a yellow revolution, and a discourse which argues that providing market information through new information and communication technologies is empowering farmers. I argue that these projects and discourse have mostly steered away from engaging with the structures of power framing rural society, and thus, have failed to bring about much change in the condition of rural people in central India. The second analytical framework is a recovery and foregrounding of alternate arenas of struggle that rural people in the Malwa region have been participating in. The platform of democratic politics is one such avenue that marginalized groups have used to make demands upon the state to provide them with support and allows them to hold the state accountable for the same. Participating in cultural projects that question and subvert the forms of caste and gender based exclusion that frame the lives of people is another such arena which provides women and adivasis (tribals) with a language of empowerment. This research argues that for the language and practice of development to have more relevance to the lives of the poor and for it to engage with the deeper aspirations in their lives, the role of these political and cultural projects as vital platforms for rural people to exercise agency and bring about change, must be recognized.by Richa Kumar.Ph.D.in History, Anthropology, and Science, Technology and Society (HAST

Design and fabrication of a Polymerase Chain Reaction (PCR) chip

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2009.Includes bibliographical references (p. 96-99).Polymerase Chain Reaction (PCR) is a molecular biology method for the in vitro amplification of nucleic acid molecules, which has wide applications in the areas of genetics, medicine and biochemistry. MEMS technology offers several advantages for the miniaturization of biological protocols like PCR, including decreased amplification time, reduced reagent consumption, disposability, target specific amplification, and functional integration. The typical three step PCR cycle consists of heating the sample to 90-95 °C to denature the double-stranded DNA complex, cooling down to 55-60 °C to anneal the specific primers to the single stranded DNA, and finally increasing the temperature to 70-75 °C for extension of the primers with thermostable DNA polymerase. The temperature sensitivity of the reaction requires precise temperature control and proper thermal isolation of the three temperature zones. In this thesis, the design of a continuous flow PCR microfluidic platform consisting of a monolithic polydimethylsiloxane (PDMS) microfluidic chip assembled on top of a thin film patterned glass base heating unit is presented. A detailed thermo-fluidic model of the device is presented to predict the performance and efficacy of the proposed design. Numerical simulations are carried out to find the temperature distribution in the device and show the suitability of the design in meeting target temperature profile. Subsequently, simulation results are substantiated with experimental results of infrared and thermocouple temperature measurement on the device.(cont.) An instrumented microfluidic platform was developed and experiments were carried out to investigate amplification efficiency. Different vapor barrier mechanisms and channel coatings were explored for minimizing sample loss. The research presented is an effort towards developing miniaturized, cost-effective, portable platform capable of replacing conventional thermocyclers.by Sumeet Kumar.S.M

Supercontinuum generation in hydrogenated amorphous silicon waveguides in the femtosecond regime

Supercontinuum generation in CMOS compatible hydrogenated amorphous silicon waveguides with femtosecond pulses at telecommunication wavelengths is experimentally studied. It is shown that stable 540 nm broad supercontinua can be obtained in 1 cm-long waveguides. © 2014 Optical Society of America.info:eu-repo/semantics/publishe

The Cancer Hub Approach for Upper Gastrointestinal Surgery During COVID-19 Pandemic: Outcomes from a UK Cancer Centre.

BACKGROUND: The coronavirus disease 2019 (COVID-19) pandemic caused unprecedented disruption to global healthcare delivery. In England, the majority of elective surgery was postponed or cancelled to increase intensive care capacity. Our unit instituted the 'RM Partners Cancer Hub' at the Royal Marsden Hospital in London, to deliver ongoing cancer surgery in a 'COVID-lite' setting. This article describes the operational set-up and outcomes for upper gastrointestinal (UGI) cancer resections performed during this period. METHODS: From April 2020 to April 2021, the Royal Marsden Hospital formed the RM Partners Cancer Hub. This approach was designed to coordinate resources and provide as much oncological treatment as feasible for patients across the RM Partners West London Cancer Alliance. A UGI surgical case prioritisation strategy, along with strict infection control pathways and pre-operative screening protocols, was adopted. RESULTS: A total of 231 patients underwent surgery for confirmed or suspected UGI cancer during the RM Partners Cancer Hub, with 213 completed resections and combined 90-day mortality rate of 3.5%. Good short-term survival outcomes were demonstrated with 2-year disease free survival (DFS) and overall survival (OS) for oesophageal (70.8% and 72.9%), gastric (66.7% and 83.3%) and pancreatic cancer resections (68.0% and 88.0%). One patient who developed perioperative COVID-19 during the RM Partners Cancer Hub operation made a full recovery with no lasting clinical sequelae. CONCLUSION: Our experience demonstrates that the RM Partners Cancer Hub approach is a safe strategy for continuing upper gastrointestinal (GI) resectional surgery during future periods of healthcare service disruption