159 research outputs found
Radiographic outcome of children older than twenty-four months with developmental dysplasia of the hip treated by closed reduction and spica cast immobilization in human position: a review of fifty-one hips
No full textPurpose: This study aimed to investigate the radiographic outcomes, rate of redislocation, and avascular necrosis of proximal femoral epiphysis (AVN) in patients aged 24 to 36 months with developmental dysplasia of the hip (DDH) treated by closed reduction (CR) and spica cast immobilization in human position. Material and methods: We reviewed the medical records of 39 patients (51 hips) aged 24 to 36 months with DDH treated by CR and spica cast immobilization in human position. The Tönnis grade, rate of redislocation and AVN, acetabular index (AI), centre-edge angle (CEA), and Severin radiographic grade were evaluated on plain radiographs. Results: Among the included 39 patients (51 hips), 15 hips (29.4%) were Tönnis grade II, 24 hips (47.1%) were grade III, and 12 hips (23.5%) were grade IV. In 47 hips (92.2%), the ossific nucleus was present at the time of CR. Stable reduction was achieved by CR in 39/51 hips (76.5%) and redislocation occurred in 12/51 hips (23.5%). Among the 12 hips that redislocated, 11 underwent open reduction and one repeated CR. Two out of 40 hips (5%) treated by CR developed AVN. Overall, 54.6% of the hips had satisfactory outcomes (39.2% Severin type I and 17.6% type II), while 45.4% had unsatisfactory outcomes (39.2% Severin type III and 3.9% type IV). Of the 40 hips treated by CR, 57.5% and 42.5% of cases had satisfactory outcomes and residual acetabular dysplasia, respectively. Six out of 11 hips (54.6%) treated by open reduction and pelvic osteotomy had satisfactory outcomes. Conclusions: Our study showed that stable CR could be achieved in 76.5% of patients aged 24 to 36 months with DDH at the time of index procedure. Satisfactory outcomes can be expected in 56.4% of the cases (5.0% AVN rate), although late acetabular dysplasia may develop in 43.6% of the hips
Consumers’ Attitudes towards Surcharges on Distributed Renewable Energy Generation and Energy Efficiency Programs
No full textabstract: Increasing penetration of energy efficiency programs and distributed renewable energy generation has imposed significant challenges for utilities to recoup their large upfront costs. There is a heated debate on what surcharges should be implemented to help the utilities recover their fixed costs; however, very few studies focus on consumers’ attitudes regarding this topic. This study surveys about 190 residential consumers throughout the United States in November 2015, investigating their preferences and attitudes towards extra demand charges and volumetric energy price increases. We apply probit models and regress consumers’ attitudes on selected socio-demographic and behavioral variables. The results indicate the homeowners are more likely to prefer demand charges when compared to renters. The demographic and behavioral factors impact consumers’ perception of bill savings from energy efficiency programs or solar panel installation and also influence how consumers perceive the fairness of utilities recovering revenue losses by increasing volumetric energy price. In this paper, we demonstrate there is preference heterogeneity among consumers and that policy makers should be aware of such preference heterogeneity and apply policy targeting based on the identified demographics and behavioral factors impacting consumer preferences.The final version of this article, as published in Sustainability, can be viewed online at: http://www.mdpi.com/2071-1050/9/8/147
Comparison of Bayesian Inference Methods for Probit Network Models
No full textThis thesis explores and compares Bayesian inference procedures for probit network models. Network data typically exhibit high dyadic correlation due to reciprocity. For binary network data, presence of dyadic correlation often leads to inefficiency of a basic implementation of Markov chain Monte Carlo (MCMC). We first explore variational inference as a fast approximation to the posterior distribution. Aware of its insufficiency in quantifying posterior uncertainties, we propose an alternative MCMC algorithm which is more efficient and accurate. In particular, we propose to update the dyadic correlation parameter using the marginal likelihood unconditional of the latent relations . This reduces autocorrelations in the posterior samples of and hence improves mixing. Simulation study and real data examples are provided to compare the performance of these Bayesian inference methods.</p
Peer Effects and Voluntary Green Building Certification
No full textabstract: Empirical evidence is provided to show that peer effects have statistically significant and positive impacts on the diffusion of green building certificates. Application and approval records of green certificates by commercial buildings in NY and AZ are used. The challenge of self-selection is addressed by the usage of fixed effects and the challenge of reflection is addressed by the time lag delay between a building’s application and its approval. Empirical results show that an additional approved LEED certificate within a zip code will increase the probability of a commercial building in the same zip code to apply for a LEED certificate by 3–4 percentage points; an additional approved Energy Star certificate within a zip code will increase the probability of a commercial building in the same zip code to apply for an Energy Star certificate by 1–2 percentage points
Parameter Identification, Simulation, Linearization and Validation of a Ship Propulsion System
No full textThis Thesis is written to obtain the Master of Science degree of Maritime Technology at Delft University of Technology. It describes a research regarding with the calibration(parameter identification), validation and linearization of a ship propulsion system model. In the meantime, the Thesis is also one sub-project under the research program "Potential of Hardware-In-the-Loop Simulation in the Towing Tank" held by Dr.Ir.A.Vrijdag. HIL (Hardware-In-the-Loop) Simulation is widely used in Engineering Technology Field, and has been proved to be a very effective, highly-efficient, economical and environmental friendly strategy in the test and development of engineering control systems. The model scale ship tests nowadays, on the other hand, need to be improved and HIL Simulation provides an innovative & creative way, therefore it is reasonable to start the program and explore more in this field
Three essays on facilitating electrification and energy efficiency from the demand side
No full textTo tackle climate change, one of the basic decarbonization strategies is to decarbonize end-use applications through electrification and energy efficiency. This dissertation comprises three essays focused on the effectiveness and implementation of the interventions aimed at electrification and energy efficiency in the building sector of the demand side. It is not easy to facilitate the transition to energy efficiency and electrification. In the building sector, much literature has found the “energy efficiency gap”, meaning that there is a persistent gap between the level of energy efficiency investment that is projected to save money and the investment that actually occurs despite the benefits from energy-efficiency investments. In many situations, the energy efficiency upgrade is in conjunction with electrification.Two types of interventions have been widely utilized to help close the “energy efficiency gap” and “electrification gap” in the building sector: price-based incentives and information-provision interventions. In my dissertation, the first essay focuses on (price-based) subsidy interventions while the other two essays focus on information-provision interventions to alter consumers’ energy demand.
The first essay aims to evaluate the effectiveness of the subsidies (rebate and loan programs) on residential air-source heat pump adoption based on the evidence from North Carolina of U.S. Many national, state-level, and city-level decarbonization plans include the transition to heat pumps. The rebate and loan programs are the two widely-adopted incentives for residential heat pumps in the U.S. Using the method of Difference-in-Differences (DID) in conjunction with spatial discontinuity, this essay estimates the impact of a rebate program (10,400 - $17,000) price premium on average. Policymakers can use the information about potential price premiums to influence consumer choices, in addition to traditional energy guides, which typically focus on fuel costs.
The third essay investigates the effectiveness of another type of information-provision campaign – special environmental events. Special environmental events, such as Earth Hour, World Environment Day, and Chinese National Energy Saving Week, can be regarded as a form of “nudge” to arouse people’s awareness of environmental protection and energy efficiency/conservation. Using a two-stage local linear method, I estimate the impacts of the three special environmental events on short-run electricity-saving behaviors using high-frequency smart meter data in Shanghai, China, for both residential and commercial consumers. I find that World Environment Day and National Energy Saving Week caused commercial users to reduce their electricity consumption by 1.35 kWh/hour and 0.6 kWh/hour intra-event, around 17% and 8% reduction compared to average consumption. Earth Hour did not lead to significant energy-saving effects for both residential and commercial users
Fingerprinting the ship propulsion system: low hanging fruit or mission impossible?
No full textIn this paper the concept of ship propulsion system “fingerprinting” is explored as an alternative for data driven models that require extensive measured datasets collected over long periods of ship operation. As a first exploratory step a model of a ship in bollard pull conditions is linearised and its transfer functions are determined. Subsequently limited experimental data, involving sinusoidal excitation of the system input at a wide range of frequencies, is used to determine the system parameters. The resulting parameter estimates compare well against previously determined values. Although the developed ideas are far from ready to be used on full scale, the authors believe that the approach is promising enough to be developed further towards full scale application.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Ship Design, Production and Operation
Synthesis and characterization of main chain crystalline polyorganosiloxanes, 1993
No full textThe goal of this project is to determine whether main chain polyorganosiloxanes exhibt liquid crystalline properties analogues to side chain polysiloxanes and to investigate the relationship between structure and liquid crystallinity. Several main chain polyorganosiloxanes with p-phenylene, p,p'-biphenylene and bisphenolene as mesogenic group and siloxene as flexible spacer were synthesized and characterized. The structures were confirmed by [H, 13C and 29Si NMR. The new polyorganosiloxanes were characterized by DSC, TGA, GPC and Polarizing Optical Microscope. The crystallinity of main chain polyorganosiloxanes is discussed
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