The continuous refill, short-burst, hand-powered water toy

Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2010.Cataloged from PDF version of thesis.Includes bibliographical references (p. 21).The water "blaster" has been one of the most popular toys because it is fun, safe, and easy to operate. The water guns have appeared in many design variations, ranging from the simple squirt gun to motorized water guns. This research proposes a new approach to water gun design. The design consists of a small single burst chamber, and an air bulb is used to pressurize the chamber between shots, creating the sense of multi-shot, large, pressurized tank. Similar to the currently popular Super Soaker, the water in this version is pressurized inside the water channel before each blast. This model also takes advantage of the pressure head between the channel and the reservoir, which is from a backpack, to have the water flow passively into the channel. The user then can pressurize the channel by hand with an air bulb and blast continuously. We implemented a prototype to demonstrate the concept.by Long Lam.S.B

Daan Go: An Entrepreneurial Case Study

Daan Go is a brand of Euro-Asian food services, now consisting of only its specialty bakery Daan Go Cake Lab. Having various retail locations across the Greater Toronto Area with current distribution channels that serve both Ontario and Quebec, Daan Go is currently focusing on expanding its bakery operations across Canada. To fulfill its vision of becoming a world-wide desserts brand, Daan Go finds itself facing unique challenges. Based on a case analysis, this report examines how Daan Go can leverage its current key capabilities, while maintaining its competitive position within the niche market it serves. This report provides an overview of Daan Go, including its retail locations, ownership, management and workforce, products and services, and its current marketing strategy. Next, the report analyzes the competitive landscape by comparing Daan Go to local speciality bakeries, including direct competitor bakeries that also specialize in Euro-Asian fusion desserts, and general competitor bakeries. The report’s situational analysis examines Daan Go’s operating environment through the use of a PESTEL analysis, Porter’s 5 Forces, and a SWOT analysis. These analyses inform the report’s recommendations to Daan Go as to its next steps as the bakery continues to expand throughout the province. Potential solutions to issues identified by Daan Go are evaluated through the use of multi-criteria decision matrixes. An implementation plan and marketing plan follows, including a 5-year financial projection. The report’s recommendations are based upon an analysis of Daan Go using recognized business theories and frameworks

A sunny future: expert elicitation of China's solar photovoltaic technologies

China has emerged as the global manufacturing center for solar photovoltaic (PV) products. Chinese firms have entered all stages of the supply chain, producing most of the installed solar modules around the world. Meanwhile, production costs are at record lows. The decisions that Chinese solar producers make today will influence the path for the solar industry and its role towards de-carbonization of global energy systems in the years to come. However, to date, there have been no assessments of the future costs and efficiency of solar PV systems produced by the Chinese PV industry. We perform an expert elicitation to assess the technological and non-technological factors that led to the success of China's silicon PV industry as well as likely future costs and performance. Experts evaluated key metrics such as efficiency, costs, and commercial viability of 17 silicon and non-silicon solar PV technologies by 2030. Silicon-based technologies will continue to be the mainstream product for large-scale electricity generation application in the near future, with module efficiency reaching as high as 23% and production cost as low as $0.24/W. The levelized cost of electricity for solar will be around$34/MWh, allowing solar PV to be competitive with traditional energy resources like coal. The industry's future developments may be affected by overinvestment, overcapacity, and singular short-term focus.info:eu-repo/semantics/publishedVersio

Human urinary mutagenicity after wood smoke exposure during traditional temazcal use.

In Central America, the traditional temazcales or wood-fired steam baths, commonly used by many Native American populations, are often heated by wood fires with little ventilation, and this use results in high wood smoke exposure. Urinary mutagenicity has been previously employed as a non-invasive biomarker of human exposure to combustion emissions. This study examined the urinary mutagenicity in 19 indigenous Mayan families from the highlands of Guatemala who regularly use temazcales (N = 32), as well as control (unexposed) individuals from the same population (N = 9). Urine samples collected before and after temazcal exposure were enzymatically deconjugated and extracted using solid-phase extraction. The creatinine-adjusted mutagenic potency of urine extracts was assessed using the plate-incorporation version of the Salmonella mutagenicity assay with strain YG1041 in the presence of exogenous metabolic activation. The post-exposure mutagenic potency of urine extracts were, on average, 1.7-fold higher than pre-exposure samples (P < 0.005) and also significantly more mutagenic than the control samples (P < 0.05). Exhaled carbon monoxide (CO) was ~10 times higher following temazcal use (P < 0.0001), and both CO level and time spent in temazcal were positively associated with urinary mutagenic potency (i.e. P < 0.0001 and P = 0.01, respectively). Thus, the wood smoke exposure associated with temazcal use contributes to increased excretion of conjugated mutagenic metabolites. Moreover, urinary mutagenic potency is correlated with other metrics of exposure (i.e. exhaled CO, duration of exposure). Since urinary mutagenicity is a biomarker associated with genetic damage, temazcal use may therefore be expected to contribute to an increased risk of DNA damage and mutation, effects associated with the initiation of cancer

Experimental investigation on the enhancement of plenum window noise reduction using solid scatterers

The sound transmission across plenum windows installed with rigid non-resonant cylindrical scatterer arrays was investigated in detail using scale-down model measurements carried out inside a fully anechoic chamber. The arrays have manifested to some extent the acoustical behaviors of virtual sonic crystals. The maximum cross section blockage ratio was 0.6. The effects of plenum window gap, array configuration, and scatterer diameter on the sound transmission characteristics were also examined. Results indicate that the window cavity longitudinal modes and the gap modes control the sound transmission characteristics at low frequencies. The upper bound of this frequency range increases with decreasing gap width. Within this frequency range, the scatterers have negligible effect on the sound transmission. At higher frequencies, the array configurations with scatterer(s) attached to the window walls result in stronger sound reduction. There are relatively higher sound transmission loss improvements around the frequencies where a full bandgap is observed. There are wide bandgaps in various lattice directions, and the present results suggest that they play a role in the broadband improvement of sound reduction

China's wind electricity and cost of carbon mitigation are more expensive than anticipated

The success of China's transition to a low-carbon energy system will be key to achieve the global level of emissions reductions needed to avoid large negative consequences from climate change. China is undergoing an impressive build up of renewable capacity, in particular wind. Using data from the Clean Mechanism Development project database between 2004 and 2012, this study shows that while China made progress in bringing down the levelized cost of wind electricity and cost of carbon mitigation (CCM), serious grid-connection issues and high wind curtailment rates resulted in a levelized cost of wind electricity that is one-half to two times higher than expected, and a CCM that is four to six times higher. Sharp drop in electricity demand, utilization rate, and coal prices in recent years may lead to even higher results.info:eu-repo/semantics/publishedVersio