Optimal carbon reduction level and ordering quantity under financial constraints

Carbon tax policy is widely adopted by many countries to curb carbon emissions. In the context of carbon tax policy, firms have more incentive to improve carbon reduction levels by reducing their carbon tax costs. However, firms need to bear carbon reduction costs that may cause shortage of capital. Thus, firms may face problems of financial constraints, which may demotivate firms to produce greener products. To address the decision‐making challenges of firms in the contexts of carbon tax policy and financial constraints, we consider a supply chain with a manufacturer who produces green products and a retailer who sells these products. Our study develops five models to investigate the two firms’ optimal wholesale price, carbon reduction level and ordering quantity, according to the manufacturer and retailer with or without financial constraints. Our goal in this study is to explore how carbon tax policy and banks’ interest rates affect the profits of the two firms, supply chain and consumer surplus. Certain managerial insights are obtained as follows. We demonstrate that carbon tax policy and banks’ interest rates demotivate the manufacturer to produce greener products and demotivate the retailer to order more products. If the interest rate to the manufacturer (retailer) is relatively low, then the manufacturer with financial constraint benefits (harms) the consumers compared with the retailer with financial constraint. Importantly, our analysis suggests that carbon tax policy harms the firms but benefits consumers, and the government in some conditions should reduce unit carbon tax.     

What’s the middle ground? Institutionalized vs. emerging water-related stakeholder engagement processes

Abstract

In this day and age, it is widely argued that stakeholder engagement in water-related decision-making processes yields many benefits, including legitimacy, acceptance and trust. Key legal frameworks, such as the European Water Framework Directive and the Aarhus Convention, have spurred the emergence of formal forms of stakeholder engagement. On the other hand, many engagement processes are spontaneous and self-organized. This article investigates the strategies used in formal (government-led) and informal (bottom-up) engagement processes in search of a middle ground. To this end, case studies in the Netherlands, the United States, Uganda and Ethiopia are analyzed using the OECD’s stakeholder engagement checklist. We conclude with reflection on the ways forward to make formal and informal stakeholder engagement complementary.     

Quantitative assessments of performance and robustness of maintenance policies for stochastically deteriorating production systems

Over the last few decades, many efforts have been invested in improving the economic performances of maintenance policies for stochastically deteriorating production systems. However, with the development of complex production systems, maintenance managers are interested not only in cost saving, but also in how to trustworthily plan and allocate the required maintenance budget. In this context, the robustness of maintenance policies which is related to the maintenance cost variability from a renewal cycle to another plays a pivotal role. This research deals with a quantitative approach to jointly assess the economic performance and robustness of some representatives of two most well-known classes of maintenance policies: time-based and condition-based maintenance. To this end, we first propose a new cost criterion which combines the long-run expected cost rate and standard deviation of maintenance cost per renewal cycle. Then, we develop and compare the associated mathematical cost models of the considered maintenance policies on the basis of the Gamma degradation process and the theory of stochastic renewal processes. The comparison results under different situations of maintenance costs and system characteristics show that the optimal configuration of maintenance policies gives the best compromise between the performance and robustness, and is mostly affected by the system downtime. Under this aspect, the condition-based maintenance remains more profitable than the time-based maintenance. Still, maintenance managers could implement condition-based maintenance policies that efficiently control the downtime to maximise the maintenance effectiveness of production systems from both performance and robustness viewpoints.     

某复杂金多金属矿石选矿试验研究

吉尔吉斯斯坦某金多金属矿石中伴生多种有价元素,有用矿物嵌布状态复杂且嵌布粒度细。针对矿石性质,采用铜优先浮选—金钴混合浮选工艺流程,可初步实现该金多金属矿石中有价金属的有效分选。闭路试验可获得Au品位228.00 g/t、Au回收率12.19%,Ag品位974.00 g/t、Ag回收率37.71%,Cu品位27.590%、Cu回收率80.65%的铜精矿,以及Au品位65.00 g/t、Au回收率57.22%,Ag品位28.00 g/t、Ag回收率17.86%,Co品位0.5500%、Co回收率53.02%的金钴精矿。     

地勘单位转制后税务风险识别与控制

结合“减税降费”的政策背景,以陕西省某转制地勘单位为例,引入风险控制相关理论并应用层次分析法,构建了税务风险评估指标体系,对转制地勘单位面临的税务风险进行了识别、分析、评估。研究结果表明:针对不同的税收类型,应着重关注不同方面的风险,排序前6位的风险依次为企业所得税扣除类风险、增值税决策环节风险、增值税销售环节风险、房产税计税依据风险、企业所得税税收优惠类风险、增值税采购环节风险;并对上述风险的控制机制进行了分析,从企业管控、政策优化两方面分别提出了相关对策和建议。     

某铜铅锌多金属硫化矿选矿试验研究

对某富含金银等贵金属的复杂铜铅锌多金属硫化矿进行了选矿试验研究。以BK916作铜捕收剂、BK906作铅捕收剂, 采用铜优先浮选-铅浮选-锌硫混合浮选-锌硫分离工艺回收主要有价元素, 获得了铜精矿铜品位24.26%、回收率58.21%, 铅精矿铅品位70.75%、铅回收率86.55%, 锌精矿锌品位51.53%、锌回收率89.44%, 硫精矿硫品位39.84%、回收率38.03%的良好选矿指标; 铜、铅、锌、硫4种精矿产品中金总回收率92.16%、银总回收率89.44%。     

甘肃某低品位铅锌银矿浮选试验研究

甘肃某极低品位氧化铅锌银矿,铅品位0.96%、铅氧化率37.50%,锌品位0.76%、锌氧化率32.88%,银品位207.66g/t,银主要以银锑黝铜矿的形式存在并与方铅矿共生。根据该矿的性质,优先浮选产出铅精矿,混合浮选产出铅锌精矿,并将银富集到铅精矿和铅锌精矿中。采用新型捕收剂GH,通过闭路选铅,获得了铅品位55.71%、铅回收率20.73%,银品位7 476.81g/t、银回收率14.39%的铅精矿;在闭路混选中,获得了铅品位17.61%、铅回收率37.47%,锌品位23.64%、锌回收率65.67%,银品位5 593.42g/t、银回收率59.49%的铅锌精矿。富集伴生银矿物的同时,实现了对低品位矿物的高效回收。     

Effect of Cu element on morphology of TiB2 particles in TiB2/Al−Cu composites

In order to explore the influence of Cu element on the morphology evolution of the in-situ TiB₂ particles, the 10 wt.% TiB₂ reinforced Al−5wt.%Cu based composite was prepared by mixed salt casting. The morphology characterization and transformation of TiB₂ reinforcements caused by Cu element were investigated by multi-scale microstructure characterization and statistics techniques. In the case of controlled casting, 5 wt.% Cu addition was found to transform the TiB₂ particle morphology from hexagonal plate with sharp edges and corners to hexagonal or tetragonal prism with chamfered edges and corners with the distinguishing growth steps both on the top surface and the side surface. The TiB₂ growth in Al−Cu matrix followed the rules: nano-scaled spherical nuclei—polyhedron grains—chamfered hexagonal particles—hexagonal plates—chamfered particles with obvious growth steps. The adsorption energy of Cu on different crystal surfaces of TiB₂ was caculated to reveal the influence mechanism and the results indicated that Cu was preferentially adsorbed on the (101(—)1)_TiB2 crystal planes, devoting to the small aspect ratio of TiB₂.     

Reinforcement learning for electricity dispatch in grids with high intermittent generation and energy storage systems: A case study for the Brazilian grid

Intermittent energy sources such as wind and solar have recently been growing a lot faster than dispatchable energy sources in Brazil, which made investments in energy storage systems become an attractive possibility in the country. Current operational policies for energy dispatch do not consider storage systems and need adjustments to fit this technology. With this motivation, we use reinforcement learning techniques to develop policies for managing storage systems in a grid that can handle time-varying inputs and loads, with rolling forecasts. We use a deterministic lookahead (DLA) policy which has been parametrically modified to perform well in the presence of uncertain forecasts. For realistic simulations, the base model considers important characteristics in a grid that influence the interaction between scheduling and real-time operation such as power and ramping capacities, notification times, and stochastic forecasts. The parametric modification with tunable parameters allows an optimal balance between two conflicting services provided by the storage system: time-shifting and spinning reserves. Optimal reserves ranged from 35% to 100%, depending on the tested dataset, which shows the importance of tuning. Differently from stochastic lookahead policies, which are computationally expensive, parameterized DLA policies can be applied to real-time operation after being optimized in a stochastic base model.     

Offshore manufacturing contract design based on transfer price considering green tax: a bilevel programming approach

The problem of designing offshore manufacturing contract resulting in optimal transfer price is troubling multinational companies over the past few years. This paper proposes designing offshore manufacturing contracts based on the transfer price in the form of bilevel programming problems after considering green tax. In these contract designs, a firm in a developed country sells a single product in its market. The same product is simultaneously being manufactured by another firm in a developing country with lower manufacturing cost. After anticipating the consumer demand, the seller places an order, based on which the manufacturer manufactures the ordered quantity, and offers a transfer price which in turn maximises its net profit after paying green tax to its government. While setting the transfer price, the manufacturer considers the manufacturing cost, the export duty payable to its government and the cost of shipping the product to the developed country. After buying the product from the manufacturer at the transfer price, the seller then sets the retail price which maximises its net profit after paying the import duty to its government; the retail price, however, must not be more than the maximum retail price applicable to the market. Thus, offshore manufacturing contract results in optimal after-tax profits for both the firms. An experimental study has been carried out to discuss the practical aspects of the results developed, where a US firm is offshoring its manufacturing activity to a Chinese firm in order to draw maximum profit.