David C. Denkenberger

Resilience to Global Food Supply Catastrophes

Many global catastrophic risks threaten major disruption to global food supplies, including nuclear wars, volcanic eruptions, asteroid and comet impacts, and plant disease outbreaks. This paper discusses options for increasing the resilience of food supplies to these risks. In contrast to local catastrophes, global food supply catastrophes cannot be addressed via food aid from external locations. Three options for food supply resilience are identified: food stockpiles, agriculture, and foods produced from alternative (non-sunlight) energy sources including biomass and fossil fuels. Each of these three options has certain advantages and disadvantages. Stockpiles are versatile but expensive. Agriculture is efficient but less viable in certain catastrophe scenarios. Alternative foods are inexpensive pre-catastrophe but need to be scaled up post-catastrophe and may face issues of social acceptability. The optimal portfolio of food options will typically include some of each and will additionally vary by location as regions vary in population and access to food input resources. Furthermore, if the catastrophe shuts down transportation, then resilience requires local self-sufficiency in food. Food supply resilience requires not just the food itself, but also the accompanying systems of food production and distribution. Overall, increasing food supply resilience can play an important role in global catastrophic risk reduction. However, it is unwise to attempt maximizing food supply resilience, because doing so comes at the expense of other important objectives, including catastrophe prevention. Taking all these issues into account, the paper proposes a research agenda for analysis of specific food supply resilience decisions.

Augmentation of distillate yield in “V”-type inclined wick solar still with cotton gauze cooling under regenerative effect

Abstract Water flowing over bare glass is not evenly distributed over the width of the glass cover. Effective temperature reduction in the glass cover is not possible in this case. Thin cotton gauze is used over the glass cover to solve this problem. The amount of water required to cool the glass cover is low and the flowing water is collected and fed into a hot water reservoir. Water from the hot water reservoir is directed to the wick absorber by a drip valve. The system was tested in two ways (i) regenerative effect with cotton gauze (ii) regenerative effect without cotton gauze. The inclined wick absorber ensures that the surface is always wet due to capillary action and there were no dry spots. Excess flow in the wick absorber is pumped back to the hot water reservoir. Due to low thermal inertia of the wick and regenerative effect, the system has quick start-up times, as well as higher operating temperatures. This resulted in higher distillate yield than simple solar stills. Since the hot water reservoir remained warm enough during the night hours, a reasonable amount of nocturnal distillate output was also obtained. Optimum inclination of the wick absorber was found to be 20° and mass flow rate through the wick absorber was 200 ml/minute. The system with cotton gauze produced distillate yield of 6,300 ml/m2 whereas the system without cotton gauze produced distillate yield of 5,600 ml/m2.

Expanded Microchannel Heat Exchanger: Nondestructive Evaluation

Abstract Recent theoretical developments in expanded microchannel polymer-based heat exchangers were promising, but the initial experiments underperformed simple theory. In order to understand this discrepancy, this article introduces a nondestructive methodology for characterizing polymer heat exchangers. A computerized tomography (X-ray) scan was performed to diagnose the problem. The method was tested on the expanded microchannel polymer heat exchanger to determine the variations in geometry between the theoretical and experimental heat exchanger. Channels were found to have variable heights causing flow maldistribution. The results are discussed to guide further technological development of this approach to heat exchanger design and fabrication and lays the groundwork for an advanced discretized modeling.

Classification of Global Catastrophic Risks Connected with Artificial Intelligence

A classification of the global catastrophic risks of AI is presented, along with a comprehensive list of previously identified risks. This classification allows the identification of several new risks. We show that at each level of AI’s intelligence power, separate types of possible catastrophes dominate. Our classification demonstrates that the field of AI risks is diverse, and includes many scenarios beyond the commonly discussed cases of a paperclip maximizer or robot-caused unemployment. Global catastrophic failure could happen at various levels of AI development, namely, (1) before it starts self-improvement, (2) during its takeoff, when it uses various instruments to escape its initial confinement, or (3) after it successfully takes over the world and starts to implement its goal system, which could be plainly unaligned, or feature-flawed friendliness. AI could also halt at later stages of its development either due to technical glitches or ontological problems. Overall, we identified around several dozen scenarios of AI-driven global catastrophe. The extent of this list illustrates that there is no one simple solution to the problem of AI safety, and that AI safety theory is complex and must be customized for each AI development level.

Performance Analysis of “V”- Type Solar Still with Tilt Wick and Effect of Wick Coverage

Abstract Solar distillation has yet to achieve widespread acceptance due to various technical difficulties and maintenance requirements which might not be acceptable or feasible for local communities. Emphasis has now shifted on the assimilation of locally available materials and expertise for optimum output. Coimbatore and nearby areas in South India have cotton waste material because the textile industry has flourished over the past ten years. A new design of wick and the performance of the solar still are parametrically analyzed in this paper. A “V”-type solar still of 1.5 m2 was constructed for experimental verification and data collection. The glass temperature, ambient air temperature and solar radiation were recorded during the sunny days. The effect of the tilt angle in the Coimbatore climatic conditions is also presented in this paper. The system was tested in two ways: (1) tilt basin fully covered by wick and, (2) tilt basin partially covered by the wick. Since the partial coverage of the wick yielded higher output and would be lower cost, this is the superior arrangement. The optimum tilt of the wick was found to be 25°. The system with tilt basin fully covered by wick produced distillate yield of 3,365 ml (m2-day) whereas the system with tilt basin partially covered by wick produced distillate yield of 3,640 ml (m2-day).