Analysis of Key Issues of Fixed Mobile Convergence

Fixed Mobile Convergence (FMC) is the focus of the future communications network development,on which the industry has kept strengthening its relevant research. However,before a large scale of implementation,there are still lots of key issues to be explored. The adoption of IP Multimedia Subsystem (IMS) architecture to replace the real-time services in the traditional application needs to solve the Quality of Service (QoS) problem in the IP domain,unify the method that the fixed and mobile users of the traditional circuit domain access IMS,complete the mapping of circuit domain service flow to IMS,guarantee the security of IMS bearer network,transform the traditional operation mode,and set up a new pattern adaptable to the convergence.

Analysis of Key Issues in Design Codes for Long-Span Highway Bridges

In recent years,with the continuous expansion of China's infrastructure construction,related construction work,including highway and bridge construction,has been steadily progressing.Among them,bridges are an important component of infrastructure construction,and their safety and stability are related to the travel of the masses and even the safety of their lives.China has a strict management system for bridge design specifications.This article mainly takes long-span highway bridges as an example to study the key issues of its design specifications and proposes countermeasures for related work.

The States-of-arts and Key Scientific Issues on Durability Research of Concrete Structures

Concrete has traditionally been regarded as a durable material requiring little or no maintenance. However, over the past several decades, a number of durability related problems have emerged and stimulated research into the factors relating to concrete durability globally. The challenge now facing practicing engineers is how to design and build structures that not only satisfy the specified structural requirements, but also achieve the performance levels required from a durability standpoint. Research works on concrete structural durability have been widely reported in the literature over the last several decades. In this paper, reviews of four stages of research work on durability, i e, environments, materials, components, and structures, were presented. Afterwards, the key scientific issues in this field were also pointed out.

OBLIVIOUS TRANSFER WITH ACCESS CONTROL AND IDENTITY-BASED ENCRYPTION WITH ANONYMOUS KEY ISSUING

In ACM'CCS 2009,Camenisch,et al.proposed the Oblivious Transfer with Access Control(AC-OT) in which each item is associated with an attribute set and can only be available,on request,to the users who have all the attributes in the associated set.Namely,AC-OT achieves access control policy for conjunction of attributes.Essentially,the functionality of AC-OT is equivalent to the sim-plified version that we call AC-OT-SV:for each item,one attribute is associated with it,and it is requested that only the users who possess the associated attribute can obtain the item by queries.On one hand,AC-OT-SV is a special case of AC-OT when there is just one associated attribute with each item.On the other hand,any AC-OT can be realized by an AC-OT-SV.In this paper,we first present a concrete AC-OT-SV protocol which is proved to be secure in the model defined by Camenisch,et al..Then from the protocol,interestingly,a concrete Identity-Based Encryption(IBE) with Anonymous Key Issuing(AKI) is given which is just a direct application to AC-OT-SV.By comparison,we show that the AKI protocol we present is more efficient in communications than that proposed by Chow.

Problems and countermeasures in construction of transmission line projects in permafrost regions

Construction of power transmission lines is becoming an important part of permafrost engineering in China.This paper reviews the construction status and problems of transmission lines in different countries,as well as corresponding solutions that would be of practical significance for sustainable engineering practices.Russia has the longest history of transmission line construction in permafrost areas,with transmission lines（mainly 220 kV and 500 kV） spanning approximately 100,000 km.However,all countries suffer from permafrost-related tower foundation stability problems caused by freezing-thawing hazards such as frost heave and thaw settlement,frost lifting,and harmful cryogenic phenomena.As point-line transmission line constructions,the lines,poles and towers should be reasonably selected and installed with a comprehensive consideration of frozen soil characteristics to effectively reduce the occurrence of freezing-thawing disasters.Reinforced concrete pile foundations are widely used in the permafrost regions,and construction in winter is also a universal practice.Moreover,facilitating engineering measures like thermosyphons are an effective way to reduce freezing-thawing hazards and to maintain the stability of tower foundations.

Addressing Transport Issues in Non‑Aqueous Li–air Batteries to Achieving High Electrochemical Performance

Li–air batteries are a promising type of energy storage technology because of the ultra-high theoretical specific energy.Great advances are made in recent years,including the illustration of reaction mechanisms,development of effective catalyst materials,and design of battery structures accelerating species transport.However,the application still suffers from low rate capability,poor round-trip efficiency,and unsatisfactory cycling life.Herein,we mainly focus on the species transport issues of non-aqueous Li–air batteries,including Li^(+) across the solid surfaces and the electrolyte,O_(2)solubility and diffusivity,distribution of intermediates and products,and side reactions by other components from the air.Besides,considerable emphasis is paid to expound the approaches for enhancing species transport and accelerating reactions,among which the realization of well-designed electrode structures and flowing electrolytes is of great significance for the rapid migration of O_(2)and Li^(+)and mitigating the negative effects by solid insoluble Li_(2)O_(2).Moreover,optimizing reaction interfaces and operating conditions is an attractive alternative to promote reaction rates.This work aims to identify the mechanism of transport issues and corresponding challenges and perspectives,guiding the structure design and material selection to achieve high-performance Li–air batteries.