Engineered hyporheic zones: design and applications in stream health restoration- a review

Anthropogenic deterioration of streams and rivers have affected their surface-subsurface linkages. This has led to the degradation of hyporheic zones, a sensitive interface between stream channel and its surrounding sediments, responsible for transforming pollutants, natural solutes and supporting benthic communities. Several authors have reported the influence of stream restoration measures on hyporheic exchanges and have called for the inclusion of hyporheic zone restorations in stream management. Engineered Hyporheic Zones (EHZ) is the creation of artificial transition area due to induced hyporheic flows, brought about by some feature modifications done to the stream channel or its subsurface. These feature modifications and its implications have been investigated through lab experiments, outdoor flumes, modelling and field studies for several years. This paper attempts to summarize the endeavours made in the study of EHZ and its applications in water quality improvement and habitat restoration. A comprehensive review of upto date literature with specific focus on the influence of engineered structures on hyporheic exchanges is presented, followed by the comparison of preferences opted for different studies and their limitations. The paper ends with suggestive future scope in EHZ studies and its potential as a low cost alternative treatment technology for river restoration.

Sustainable Development Economics of Enterprises in the Services Sector Based on Effective Management of Value Streams

The world’s economy has been significantly affected by the ongoing pandemic crisis. Its logical reflection is a deteriorating condition of national and regional economies and their vehicles—enterprises. Negative effects of the crisis have influenced both the manufacturing sector and the services sector, where some segments have been hit fatally. In the corporate sphere in general, including in the services sector, there has been a growing need to change the approach to corporate strategy. The strategy should be generated based on management of value-creating processes with the objective to maximize satisfaction of customers while minimizing costs. This is also the topic of this paper. A representative sample of small and medium enterprises from the services sector have been surveyed about their size, using mathematical statistics and models that have been proposed to maximize profit probability. The objective was to propose models that maximize probability of profit and, at the same time, minimize costs for each combination of value chain activities (input logistics, provision of services, output logistics, marketing and sale, servicing, and other accompanying activities, purchasing material management, science-technical development, human resources management and company infrastructure). The main outcome of this paper is the fact that we have been able to prove the functionality of the tested model, which has demonstrated the growing importance of value stream management in relation to the size of enterprises. Such a universal and structured model provides a practical tool for the definition of economic-financial, investment and personnel policies in enterprises.

Service value stream management (SVSM) - a case study

Air transport accounts for a significant portion of all wealth production in the world. In the case of Brazil, although the air transport industry is undergoing profound changes because of the economic crisis, there is enormous potential for this market to resume growth, especially when compared to the number of passengers/inhabitant of already consolidated markets, such as the United States. However, to grow in this market, airlines need to be prepared to adapt to new dynamics and overcome the effects of the economy on the industry. This paper presents a case study of an airline that in the crisis period lost its market leadership and chose to restructure the business-to-business (B2B) sales department to achieve better results in its Business Process Management (BPM). It seeks to identify which factors led the company to lose this leadership from the perspective of its customers and propose a way to review internal processes, eliminating waste, so that the company can resume its position in the market. It has been applied lean service-focused concepts to raise possible causes, identifying and optimized internal sales department flows to create a more appropriate customer value proposition, and correcting for each type of waste mapped. The objective of this case study was to apply the concepts related to the Value Stream Map tool to reduce activities that do not add value, in a service area, of a large airline. The objective was to improve the company's Business Process Management, aiming at a lean, effective and efficient process, improving the organization's performance and competitiveness.

The Municipal Solid Waste Management System with Anaerobic Digestion

This study investigated the applied methods for the collection and treatment of an organic fraction of municipal solid waste with anaerobic digestion (AD), including the effects of selective waste collection system introduction. As the research area, data from a waste treatment plant, which collects waste from about 260,000 inhabitants, was used as the selected waste management plan. Biowaste stream management was emphasized. Thus, research on energy recovery and the characteristics of digestate (nutrient and heavy metals content) obtained from biowaste AD was performed. The results of the studies and their quantitative data were interpreted. A significant discrepancy between the assumptions and the actual situation was revealed (up to 20% year-on-year regarding biowaste). An underestimation of the amount of waste when planning was noted. AD ensures energy recovery from biowaste, which can cover facility electricity needs and material recovery. The digestate might find agricultural usage and become an ecological product. The content of nitrogen (1.5%dry matter), phosphorus (0.55%dry matter), potassium (1.0%dry matter), and organic carbon (16.0%dry matter) indicate a positive impact on crops. Furthermore, it can improve the economic balance, by replacing costs with sales revenues.

Used Batteries in the Municipal Solid Waste Stream: Management of the Challenges and Heavy Metal Contents

Background: Hazardous materials, such as used batteries contain heavy metals and enter the solid waste stream, ending up in landfills. The present study was done to determine the amount of used batteries in Iran and their heavy metal contents in the batteries entering the landfill site in Tabriz. Methods: A questionnaire was applied to assess the current management condition of the used batteries in Tabriz and Ardabil as the representative cities of the entire country. The heavy metal content of 15 AA-sized batteries was determined by inductively coupled plasma. Results: Our findings showed that 14.7% of the used batteries in Iran have been imported, and approximately 76% and 24% of the batteries analyzed at the landfill site were AA-sized and cellphone batteries, respectively. In 60% of the studied batteries, the total heavy metal content was less than 100 mg/kg. Conclusion: The results of this study could be a useful reference for global and local policymakers in developing effective regulations for the use of cleaner materials in the battery industry and controlling the used batteries from their generation to the end of the battery life

Urbanization and stream ecosystems: the role of flow hydraulics towards an improved understanding in addressing urban stream degradation

Catchment urbanization is widely recognised as a primary driver of stream degradation by increasing stormwater runoff causing major changes to key ecosystem processes. Reinstating the ‘natural’ hydrogeomorphic conditions is central in designing successful, self-sustaining restoration actions. However, addressing urban stream degradation by re-establishing the hydrogeomorphic conditions remains a challenge and comparatively limited measurable progress has been observed particularly achieving ecological objectives. This paper articulates that stream restoration goals might be better achieved when management measures take a broader approach that considers anticipated hydraulic conditions effects that liaise relationships between flow and ecology. The study argues that fluvial systems are characterised by complex and dynamic ecosystem processes primarily governed by the hydraulic conditions (e.g. velocity, depth, shear stress), thus, as the practice of addressing urban stream restoration becomes increasingly common, it is critical to explore and understand the anticipated response of the hydraulic conditions. This paper describes how hydraulic regime consideration provides further opportunity for a holistic approach to urban stream management given their capacity to account for multiple ecological and geomorphic objectives. The paper suggests that developing suitable flow-biota-ecosystem processes nexus is critical towards addressing urban stream degradation and hydraulic consideration in restoration actions provide an important step towards that. The paper discusses opportunities to evolve management actions to achieve restoration goals by highlighting how the management of the two key levers (addressing altered flow regime and morphology) to improve the hydraulic conditions can help to address the urban stream disturbance.

High-Performance Multi-Stream Management for SSDs

Owing to their advantages over hard disc drives (HDDs), solid-state drives (SSDs) are widely used in many applications, including consumer electronics and data centers. As erase operations are feasible only in block units, modification or deletion of pages cause invalidation of the pages in their corresponding blocks. To reclaim these invalid pages, the valid pages in the block are copied to other blocks, and the block with the invalid pages is initialized, which adversely affects the performance and durability of the SSD. The objective of a multi-stream SSD is to group data by their expected lifetimes and store each group of data in a separate area called a stream to minimize the frequency of wasteful copy-back and initialization operations. In this paper, we propose an algorithm that groups the data based on input/output (I/O) types and rewrite frequency, which show significant improvements over existing multi-stream algorithms not only for performance but also for effectiveness in covering most applications.