let r be an associative ring with unity. an element a in r is said to be r-clean if a = e+r, where e is an idempotent and r is a regular (von neumann) element in r. if every element of r is r-clean, then r is called an r-clean ring. in this paper, we prove that the concepts of clean ring and r-clean ring are equivalent for abelian rings. further we prove that if 0 and 1 are the only idempotents...

let r be an associative ring with unity. an element a in r is said to be r-clean if a = e+r, where e is an idempotent and r is a regular (von neumann) element in r. if every element of r is r-clean, then r is called an r-clean ring. in this paper, we prove that the concepts of clean ring and r-clean ring are equivalent for abelian rings. further we prove that if 0 and 1 are the only idempotents...

In this paper we consider a dynamic nonzero-sum game between the polluting firms and the authorities. Although the proposed game is not easily solvable for the feedback case, i.e., it is not the linear quadratic case of game and not a degenerated case, we calculate explicitly a stationary feedback equilibrium. In the proposed game the regulator has the ability to turn the optimal allocation of ...

We analyze a repeated game in which countries are polluting and investing in technologies. While folk theorems point out that the first best can be sustained as a subgame-perfect equilibrium when the players are sufficiently patient, we derive the second-best equilibrium when they are not. This equilibrium is distorted in that countries over-invest in technologies that are “green” (i.e., strate...

Abstract: We assess the effectiveness of China’s Two Control Zones (TCZ) policy, an environmental policy that tightens the control of acid rain and the emission of sulfur dioxide (SO2) in targeted areas. To identify the effect of the policy on industrial activities, we use the difference-in-differences (DID) method to study industry-level activities in China’s prefectures based on a unique firm...

In this study, solar powered airplanes and hybrid electric are examined. Today, with the depletion of fossil fuels their harmful effects on environment becoming visible, it has become necessary to use alternative energy more in every field. Solar one most used renewable sources as a result achieving desired level performance developing technology. As result, construction flying been accelerated...

Industrial and mining activities are recognized as major sources of soil pollution. This study proposes an index system for evaluating the inherent risk level of polluting factories and introduces an integrated risk assessment method based on human health risk. As a case study, the health risk, polluting factories and integrated risks were analyzed in a typical industrial and mining gathering a...

In response to increasing political and individual awareness of the need to address the social and environmental costs of unsafe, inefficient and highly polluting driving styles, the Foot-LITE research project seeks to deliver innovative driver/vehicle interface systems and services to encourage and hopefully persuade sustained changes to driving styles and wider travel behaviour. Stakeholders’...