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【Objective】This paper discusses full lifecycle energy efficiency of optical communication systems in the purpose of energy conservation and carbon reduction. It aims to establish a universal model for description of energy efficiency, which covers all stages of system lifecycle, and it is not limited to specific technologies or network structures. It also analyzes the key influencing factors for improvement of energy efficiency of optical communication systems.【Methods】This paper explores the useful work and energy consumption of optical communication systems, to establish a universal model for energy efficiency. In the expression of useful work, in addition to the commonly used factor data rate, distance factor is introduced as an important factor. The paper recommends that the value generated by data transmissions which meet specific quality requirements and maintaining network connectivity in specific scenario applications should be considered in the description of the useful efficacy. The description method is named as comprehensive useful efficacy. In the discussion of energy consumption, the system lifecycle is decomposed into four stages: manufacturing, installation and construction, operation and maintenance, and waste recycling. Main influencing factors of energy efficiency improvement are discussed based on the established model.【Results】Main results of the research include: (1) Distance factor can be one of the main factors for evaluating the useful work of a system, and distance factors affect energy consumption at various stages of the system's lifecycle; (2) For new scenarios and applications, setting weights for data transmissions which meet specific quality requirements and assigning values for maintaining connectivities status in description of the system useful work could reflect the value brought by the energy cost of the system to meet the needs of scenario applications; (3) Energy consumption factors of each stage of the life cycle should be considered in evaluation of energy consumption of the full lifecycle, and the energy consumption of each stage should be converted into unit time based on the system operating life for accumulation; (4) Optimized network topology and routing design, reduction of line losses, as well as evolution of optical transmission technology and equipment/facility energy saving technologies, are important means to reduce energy consumptions throughout the entire lifecycle of the system and improve the energy efficiency.【Conclusion】This paper discusses the comprehensive useful work and full life cycle energy consumption of optical communication systems, and establishes a universal model to describe the full life cycle energy efficiency of the system. This model takes distance as an important influencing factor in the expression of the useful efficiency and also energy consumption of the system, which corresponds the value of the optical communication system based on communication distance with the energy consumption in the life-cycle caused by distances. It also suggests considering the value generated by data transmissions which meet specific quality requirements and maintaining network connectivity in the evaluation of the useful efficiency. This model could comprehensively evaluate the energy efficiency of optical communication systems, for improvements of system energy efficiency, and could adapt and promote applications of optical communication systems in new scenarios.

A rotor system in rubbing is shown to exhibit complex phenomena including period-doubling bifurcation,quasiperiodic and chaotic motions due to itsstrongly nonlinear dynamic characteristics. Based on the mechanical model of a single-disk flexible Jeffcott rotor,the fourth-order Runge-Kutta method with variable step size was used for numerical simulation. The essential relationship between the model parameters and the dynamic characteristics of the system is studied by used periodic bifurcation diagrams,axis trajectory diagrams,Poincaré section diagrams and maximum rubbing force diagrams. The simulation results show that the change of stiffness ratio has great influence on the dynamic characteristics of the system. With the increase of damping coefficient,the type of periodic motion mode of the system decreases obviously,and the chaotic region decreases accordingly. When the eccentricity ratio increases,the dynamic characteristics of the system become more complex. Meanwhile,the maximum rubbing force increases significantly,and the rubbing events of the rotor system become more serious. The calculation and analysis in this paper may be helpful for avoided rubbing events and limited maximum friction in the design of single-disk flexible rotor.

A study is made on the effect of market reform, the division of labor among enterprises, and the increasing advantage of small-scale enterprises on the machine tool industry in China. Restricting division of labor in a large state-controlled enterprise results in inefficiency and low productivity. Studies show that market reforms should focus on eliminating inefficient enterprises and promoting specialization in certain production processes. Inter-enterprise transactions and competition brought about by market reforms are integral part of any economic program.

Business enterprises at the state, urban collective, township-village and joint venture levels are evaluated for their technical and allocative efficiency in China's garment industry. It is shown that new socialist-oriented and joint venture companies exhibited greater efficiency than their traditional counterparts. In addition, even economic reform will not fully elevate the status of traditional businesses to the level of their more modern socialist counterparts.

Abstract Both Djordjević (2007) and Takane et al. (2007) have studied the equivalent conditions for and . In this note, we derive the necessary and sufficient conditions for , , and .

Current coupled atmosphere-ocean general circulation models can not simulate decadal variability well, and model errors would have a significant impact on the estimation of decadal predictability. In this study, the nonlinear local Lyapunov exponent method is adopted to estimate the limit of decadal predictability based on 9-year low-pass filtered sea surface temperature (SST) and sea level pressure (SLP) observations. The results show that the limit of decadal predictability of the SST field is relatively large in the North Atlantic, North Pacific, Southern Ocean, tropical Indian Ocean, and western North Pacific, exceeding 7 years at most locations in these regions. In contrast, the limit of the SST field is relatively small in the tropical central-eastern Pacific (4-6 years). Similar to the SST field, the SLP field has a relatively large limit of decadal predictability over the Antarctic, North Pacific, and tropical Indian Ocean (>6 years). In addition, a relatively large limit of decadal predictability of the SLP field also occurs over the land regions of Africa, India, and South America. Distributions of the limit of decadal predictability of both the SST and SLP fields are almost consistent with those of their intensity and persistence on decadal timescales. By examining the limit of decadal predictability of several major climate modes, we found that the limit of decadal predictability of the Pacific decadal oscillation (PDO) is about 9 years, slightly lower than that of the Atlantic multidecadal oscillation (AMO) (about 11 years). In contrast, the northern and southern annular modes have limits of decadal predictability of about 4 and 9 years, respectively. However, the above limits estimated using time-filtered data may overestimate the predictability of decadal variability due to the use of time filtering. Filtered noise with the same spectral characteristics as the PDO and AMO, has a predictability of about 3 years. Future work is required with a longer period of observations or using a more realistic model of decadal variability to assess the real-time decadal predictability. [ABSTRACT FROM AUTHOR]