On the Ruled surfaces in Minkowski 3-space R1^3

INTRODUCTIONLet ú3={(x1,x2,x3)|x1,x2,x3∈ú} be a 3D vector space, x=(x1,x2,x3) and y=(y1,y2,y3) be two vectors in ú3. The pseudo scalar product of x and y is defined by     

碘、溴和叠氮化物水溶液中的声化学反应

1　Ｉｎｔｒｏｄｕｃｔｉｏｎ　Ｔｈｅｃｈｅｍｉｃａｌｅｆｆｅｃｔｓｏｆｕｌｔｒａｓｏｕｎｄａｒｅｄｕｅｔｏｈｉｇｈｐｒｅｓｓｕｒｅｐｒｏｄｕｃｅｄｄｕｒｉｎｇｖｉｏｌｅｎｔｃｏｌｌａｐｓｅｏｆｃａｖｉｔａｔｉｏｎｂｕｂｂｌｅｓ.Ｔｈｅｒｅａｃｔｉｏｎｓｄｏｎｏｔｔａｋｅ ｐｌａｃｅｈｏｍｏｇｅ ｎｅｏｕｓｌｙｉｎｔｈｅｓｏｌｕｔｉｏｎｂｕｔｉｎ”ｈｏｔｓｐｏｔｓ”ｗｈｅｒｅｃａｖｉ ｔａｔｉｏｎｂｕｂｂｌｅｓｐｕｌｓａｔｅｏｒｃｏｌｌａｐｓｅ .Ｄｕｒｉｎｇｔｈｅａｄｉａｂａｔ ｉｃｃｏｍｐｒｅｓｓｉｏ…     

COBRA framework to evaluate e-government services: A citizen-centric perspective

E-government services involve many stakeholders who have different objectives that can have an impact on success. Among these stakeholders, citizens are the primary stakeholders of government activities. Accordingly, their satisfaction plays an important role in e-government success. Although several models have been proposed to assess the success of e-government services through measuring users' satisfaction levels, they fail to provide a comprehensive evaluation model. This study provides an insight and critical analysis of the extant literature to identify the most critical factors and their manifested variables for user satisfaction in the provision of e-government services. The various manifested variables are then grouped into a new quantitative analysis framework consisting of four main constructs: cost; benefit; risk and opportunity (COBRA) by analogy to the well-known SWOT qualitative analysis framework. The COBRA measurement scale is developed, tested, refined and validated on a sample group of e-government service users in Turkey. A structured equation model is used to establish relationships among the identified constructs, associated variables and users' satisfaction. The results confirm that COBRA framework is a useful approach for evaluating the success of e-government services from citizens' perspective and it can be generalised to other perspectives and measurement contexts.