Supraglacial debris thickness and supply rate in High-Mountain Asia

Supraglacial debris strongly modulates glacier melt rates and can be decisive for ice dynamics and mountain hydrology. It is ubiquitous in High-Mountain Asia (HMA), yet because its thickness and supply rate from local topography are poorly known, our ability to forecast regional glacier change and streamflow is limited. Here we resolved the spatial distribution of supraglacial debris thickness (SDT) for 4401 glaciers in HMA for 2000-2016, via an inverse approach using a new dataset of glacier mass balance. We then determined debris-supply rate (DSR) to 3843 of those glaciers using a debris mass-balance model. Our results reveal high spatial variability in both SDT and DSR, with supraglacial debris most concentrated around Everest, and DSR highest in the Pamir-Alai. We demonstrate that DSR and, by extension, SDT increase with the temperature and slope of debris-supply slopes regionally and that SDT increases as ice flow decreases locally. Our centennial-scale estimates of DSR are an order of magnitude lower than millennial-scale estimates of headwall-erosion rate from 10Be cosmogenic nuclides, indicating that debris supply to the region's glaciers is highly episodic. We anticipate that our datasets will enable improved representation of the complex response of HMA's glaciers to climatic warming in future modelling efforts.

CONTRIBUTION TO THE HYDROCHEMICAL KNOWLEDGE OF AQUIFERS IN THE DEPARTMENT OF TANDJILE-EAST, SOUTHERN CHAD

The province of Tandjile is one of the 23 provinces of the Republic of Chad. The drinking water supply rate in this region remains low. Part of the population obtains its water supply through open wells and / or surface water. Climatic and anthropogenic variations in recent years have shown how much groundwater can be influenced both in terms of its quality and its quantity to be used. The objective of this study is to provide knowledge on the state of the hydrodynamic and hydrochemical parameters of the aquifer of the department of Tandjile-Est to help decision-makers in their approach. This study is based mainly on existing data collected in Chadian institutions and literary journals. The analysis of these data showed that the lithology is represented by clayey, sandy, lateritic formations and clay-sandy mixtures. The aquifers are sandy and sandy-clayey. The groundwater temperature values are in equilibrium with those of the air, the pH shows values close to neutrality and the electrical conductivity below standards (Chad, WHO). The groundwater in the study area is not very mineralized and the concentrations of elements indicating contamination (nitrates, chloride, etc.) are clearly in traces. Chemical analyzes revealed two chemical facies: calcium and magnesium bicarbonate and sodium and / or potassium bicarbonate.

SELECTION OF THE CONSTRICTION FACTOR FOR VENUS FLYTRAP OPTIMIZATION

This paper proposes venus flytrap optimization (VFO) with constriction factor (VFO-CF) for improving the convergence of the algorithm. The constriction factor has a significant impact on the performance of VFO-CF; its impact was inspected based on benchmark functions. Herein, the property of the constriction factor and the guidelines for determining the optimal parameter values are defined. The proposed method is tested on benchmark functions, and the obtained results are compared with existing VFO results. The water supply rate is tested in the range [4.1, 4.2], which is generally reasonable for the benchmark functions.

Trade Credit with Barter in a Capital-Constrained Supply Chain

Barter has emerged to alleviate capital pressure, maximize the circulation of goods, and facilitate the disposal of excess inventory. This study considers a two-level supply chain consisting of a manufacturer and a capital-constrained retailer with trade credit, in which the retailer exchanges unsold products for needed subsidiary products on a barter platform. The retailer’s optimal order quantity and the manufacturer’s wholesale price are derived, and the influences of barter and other factors on the equilibrium strategy and performance of the supply chain are examined; these results are verified and supplemented by numerical simulation. We find that the retailer can increase profit by bartering when facing highly uncertain demand, that the retailer’s optimal order quantity increases with the supply rate and demand for subsidiary products, and that both manufacturer and retailer benefit from the high supply rate of subsidiary products. However, barter induces the manufacturer to raise the wholesale price to prevent its profit from being harmed. In addition, the manufacturer suffers from the retailer’s initial capital.

Sedapp v2021: a nonlinear diffusion-based forward stratigraphic model for shallow marine environments

The formation of stratigraphy in shallow marine environments has long been an important topic within the geologic community. Although many advances have been made in the field of forward stratigraphic modeling (FSM), there are still some areas that can be improved in the existing models. In this work, the authors present our recent development and application of Sedapp, which is a new nonlinear open-source R code for FSM. This code uses an integrated depth–distance related function as the expression of the transport coefficient to underpin the FSM with more alongshore details. In addition to conventional parameters, a negative-feedback sediment supply rate and a differentiated deposition–erosion ratio were also introduced. All parameters were implemented in a nonlinear manner. Sedapp is a 2DH tool that is also capable of running 1DH scenarios. Two simplified case studies were conducted. The results showed that Sedapp not only assists in geologic interpretation but is also an efficient tool for internal architecture predictions.

Importance of epidemic severity and vaccine mode of action and availability for delaying the second vaccine dose

Following initial optimism regarding the potential for rapid vaccination, delays and shortages in vaccine supplies have occurred in many countries. Various strategies to counter this gloomy reality and speed up vaccination have been set forth, of which the most popular approach has been to delay the second vaccine dose for a longer period than originally recommended by the manufacturers. Controversy has surrounded this strategy, and overly simplistic models have been developed to shed light on this issue. Here we use three different epidemic models, all accounting for the actual COVID-19 epidemic in the Czech Republic, including the rise and eventual prevalence of the B.1.1.7 variant of SARS-CoV-2 virus and real vaccination rollout strategy, to explore when delaying the second vaccine dose from 21 days to 42 days is advantageous. Using the numbers of COVID-19-related deaths as a quantity for comparing various model scenarios, we find that vaccine mode of action at the beginning of the infection course (preventing contagion and symptom appearance), mild epidemic and sufficient vaccine supply rate call for the original inter-delay scenario of 21 days regardless of vaccine efficacy. On the contrary, for vaccine mode of action at the end of infection course (preventing severe symptoms and death), severe epidemic and low vaccine supply rate, the 42-day inter-dose period is preferable, at any plausible vaccine efficacy.

Flume Experiments Evaluating the Efficacy of a Large Wood Trap Featuring Horizontal Rods

Large wood (LW) disasters, which often accompany sediment-related disasters, occur worldwide. To prevent and mitigate such disasters, we developed a unique LW trap featuring horizontal rods aligned with the flow. When LW enters the trap, it is scooped up by the rods and thus separated from water and sediment. We explored trapping efficacy using a flume of slope 0.087. Water circulated at a constant rate of 1.8 L/s, LW was added to the flow, and the trapping rates were measured. We focused on the relative wood length (Lw) with respect to the horizontal rod spacing (Sr), the number of LW units supplied, and the supply rate. A longer relative length (Lw/Sr) of LW was associated with a higher trapping rate. The trapping rate was also high when the LW number or supply rate was high. The critical Lw/Sr value was 1.5; below this value, LW was not trapped. This study yields the basic information needed to design traps featuring horizontal rods to mitigate LW-related disasters.

Improvement Methods for Supply Performance in Emergency Interconnection Plans

When operating a water supply network (WSN), pipe failures and water service interruptions are inevitable. A large-scale water service interruption decreases the reliability of a WSN; therefore, an emergency interconnection plan (EIP) is adopted to prevent it. To establish an EIP involving emergency interconnection pipes, in most cases, only the operation plan is considered. However, it is required to evaluate possible interconnected supply areas (PISAs) from the EIP to achieve the purpose of the EIP. It is obvious that PISA is dependent on the structure of the WSN, elevation difference between the adjacent interconnected blocks, size and location of the emergency interconnection pipes, and inline pumping station. In this study, we categorized the reasons resulting in insufficient PISA from the EIP and suggested improvement methods such as increasing the pipe diameter, new pumping stations, adding emergency interconnection pipes, and adding pressure relief valves. To quantify the effect of the improvement methods on the performance of the EIP, we applied them to a real WSN and estimated the emergency supply rate for each improvement method by using Pressure Driven Analysis (PDA) was used as the hydraulic simulation tool. Consequently, each improvement method increased the PISA and the emergency supply rate on the network. Thus, the suggested method will be used in the design and operation of EIPs to improve their performance.