Life as a cosmic imperative?

The origin of life on Earth may be divided into two stages separated by the first appearance of replicable molecules, most probably of RNA. The first stage depended exclusively on chemistry. The second stage likewise involved chemistry, but with the additional participation of selection, a necessary concomitant of inevitable replication accidents. Consideration of these two processes suggests that the origin of life may have been close to obligatory under the physical-chemical conditions that prevailed at the site of its birth. Thus, an extrasolar planet in which those conditions were replicated appears as a probable site for the appearance of extra-terrestrial life.     

Energetical Theories on Fatigue Life Prediction

Current developments on fatigue life predictionmethods have been systematically reviewed.In con-sideration of the irreversibility of energy dissipationduring fatigue damage process,the main contentsfor fatigue damage estimation and localizedequivalence as well as simulation models have beenestablished.A frame of energy-based fatigue lifeprediction method has been proposed,meanwhile,the procedure in application to a practical structurecomponent has been described.     

我的音乐生活Fantastic Music Life

光盘这个曾几何时的稀罕物，随着科技的发展已经成为每个电脑使用者必不可少的日常用品，尽管移动硬盘和u盘的诞生为人们提供了新的选择，但是空白光盘的通用性，价格优势和对比u盘的大容量是前两者所无法比拟的，所以光盘仍是广大电脑用户记录数据的首选，没有人的硬盘能够坚持20年，但是20年历史的光盘至今仍能带来委婉动听的音乐，某公司最新推出的刻录光盘更是宣称能为我们将数据保存100年。     

The Theoretical Summary and Mathematics Expression on the Regulation of Life in Meridian（Jingluo经络）Science

The meridian（Jingluo经络）is a core principle of traditional Chinese medicine．The meridian plays a central role in the regulation of human health and vitality．In the past５０years,the scientific evidence has been gathered via our physiological experiments to confirm the biological basis of the human meridian pathway phenomenon．Meridian Science has been established as a new branch of natural science to advance and promote the study of this important phenomenon for human life．In this paper,the authors describe the theoretical concept of the meridian and mathematics expression,its relationship to an efficient meridian circadian cycle,and its significance to human life．     

Life Expectancy Study of Small Diameter Type E, K, and N Mineral-Insulated Thermocouples Above 1000???C in Air

Very little if any current data is available for the life expectancy of very small diameter thermocouples operating at high temperatures, greater than 1000???C. Over the past 10?years significant changes in the supply stream of the materials used to manufacture base metal thermocouples have occurred. In many industrial applications, small diameter thermocouples are the only solution for high-temperature measurements. This study has been undertaken to assess the performance of small diameter magnesium oxide insulated metal sheathed thermocouple sensors at or above 1000???C. Three different American Society of Testing and Materials (ASTM) standard letter designation thermocouple types have been included in this study, Types E, K, and N. Inconel 600 and 316 stainless, for three different sizes, 0.5?mm, 1.0?mm, and 1.5?mm, have been tested for different thermocouple types. Each group of sensors was placed in an equalization block in air for a maximum of 500?h or until failure. The performance of 0.5?mm diameter thermocouples varies widely depending on the thermocouple type, sheath material, and test temperature. Larger diameter Type K and N thermocouples show very little drift up to 500?h at 1100???C. The data for each test was collected at 10?s intervals for the entire duration of the test. Data for the sensor drift and subsequent failure are presented.     

Effect of Notches and Environment on Cyclic Life of Alumina

Four-point bending cyclic fatigue testing has been performed for alumina specimens with two kinds of notch radius in corrosive environments. Cyclic life is found to be dependent on notch radius and environments, the tests also show that the fatigue notch factor Kf is roughly equal to the theoretical notch factor Kt, the fatigue strength and fatigue limit σc are reduced in environment in the sequence: formamide-room air-distilled water     

Computational‐Experimental Approach to Prediction of Mass‐Transfer Processes in Metallic Coatings of Gas‐Turbine Blades and Their Service Life

A computationalexperimental approach to analysis of longtime processes of mass transfer of aluminum in metallic MCrAlY coatings of gasturbine blades and to prediction of their service life is proposed. The approach is based on the mathematical model describing the oxidation and diffusion processes in the coating and in the alloy of a blade, the parameters of which are identified by the data of shorttime experiments. The results of theoretical and experimental determination of the aluminumconcentration distributions in the coating and in the basic alloy of a gasturbine blade and the results of prediction of the service life of the coating are presented. It is shown that this approach allows one to perform analysis of longtime processes of masstransfer in metallic coatings of gasturbine blades and predict their service life with a high degree of accuracy.     

A Valid Method for the Forecasting Economic Life Circle of Equipment

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Scatter Analysis of Fatigue Life and Prediction of S–N Curve

In this study, the effects of salt solution, the presence of notch on fatigue life scatter, and sample size selection for estimation of fatigue life under different probabilities and confidence levels have been investigated. Comparison has been made with smooth specimen tested in air medium. It is seen that notches have significantly higher effect than other factors (salt solutions, smooth geometry, etc.). The minimum number of specimens required for fatigue life estimation within tolerable error, R _o, at different fatigue testing conditions has also been presented both for log normal and Weibull distribution models. It has been found that estimation of fatigue life using Weibull model needs higher sample size than log normal model. Beyond a certain sample size, fatigue life estimation is independent of sample size. The article also presents a method for minimum sample size selection procedure to estimate fatigue life or to draw S?CN curve.     

Fatigue-Creep Interaction Fracture Maps and Life Prediction under Combined Fatigue-Creep Stress Cycling

The purpose of this paper is to introduce sys-tematically the theory of fatigue-creep interactionfracture map and its application.     

A New Method for Forecasting the Life Test Data of Mechanical Products

1 IntroductionThe Grey model of GM(l,l) is veq imPortant in the aPPlicahon of the grey system theoriesfoforasting model. It is widely used in many areas. The grey forecasting model is introduced tothe field of reliability engineering, in which the system of life test is regarded as a grey systemincluding the unknown infOrmation, and the test dsta is regarded as the grcy value. The life testdata are queued from small to big and added up once; then the data sequence vaxies in the formof expon…     

A Study on Engine Life Span Based on Engine Assembly Quality Analysis

1 IntroductionThe useful lifC (or ndleage between overhaul) is an imPortant index to assess the assebolyquality of an engine. TO a considerable degree, the useful life of an engine is dePendent on themath characters of every friction pair of crank link mechanisms, esPecially the statUs ofCylinders and pistons. The wear value of a cylinder is the most used parameter to decide whetheran engine shOuld be ovCrhauled or not.Because there are varous errors in every Part of the engine, cylinder b…     

An Investigation into the Life Cycle Cost of a Typical Computer Numerical Control Machine

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Thermal—Mechanical Fatigue Behavior and Life Analysis of Cast Ni—base Superalloy K417

In-phase(IP) and out-of-phase(OP)thermal-mechanical fatigue(TMF) behavior of cast Ni-base superalloy K417 was studied.All experiments were carried out under total strain control with temperature cycling between 400-850℃.Both in-phase and out-of-phase TMF specimens exhibited cyclic hardening followed by cyclic softening at the minimum temperature.Besides,they cyclically hardened in the early stage of life followed by cyclic softening at the minimum temperature.Besides,they cyclically hardened in the early stage of life followed by cyclic softening at the maximum temperature.OP TMF life was longer than of IP TMF.Various damage mechanisms operating in different controlled strain ranges and phasing were discussed.A few life prediction methods for isothermal fatigue were used to handle TMF fatigue and their applicability to superalloy K417 was evaluated.The SEM analysis of the fracture surface showed that transgranular fracture was the principal cracking mode for both IP and OP TMF.Oxidation was the main damage mechanism in causing shorter fatigue life for IP TMF compared with OP TMF.     

Standardization in the Cultural Heritage in China

China has begun its standardization process in the cultural heritage since 1960.The standards contributed a lot to the development of the heritage conservation practices. In this paper, the author summaries the existing condition of standardization in the cultural heritages and museums field in China, and presents Standards for the Classification of Collected Cultural Heritages. Also this paper points out the problems which exist in the standardization in the cultural heritage, and gives the advice to solve these problems.     

What happened in 1953? The Big Flood in the Netherlands in retrospect

During the weekend of Saturday 31 January to Sunday 1 February 1953, a storm tide raged across the northwest European shelf and flooded the low-lying coastal areas of the countries around the North Sea. The peak high waters occurred during the night and the storm surprised many people in their sleep. The resulting disaster in terms of loss of life and damage to infrastructure was enormous. In the Netherlands, 1836 people fell victim to the flood; in the UK and Belgium, the casualties were 307 and 22, respectively. The large number of fatalities in the Netherlands was related to the fact that much of the affected area is below sea-level.This paper focuses on the case of the Netherlands. It discusses the history of land reclamation, and the fact that living in low-lying areas protected by dykes, often below sea-level, is an accepted fact of life in the Netherlands. The historical approach to dyke maintenance is then outlined, and the state of the dykes in the early twentieth century and after the war is discussed. The characteristics of the storm and the flood are discussed, along with people's experiences of the first hours and days following the flood. The impact of this human stress has often been lasting--many survivors continue to live with daily memories of the flood. Attention is given to the large-scale rescue and relief efforts, the closure of the dykes during the following nine months and the concept of the Delta Plan, designed to prevent such a large-scale disaster ever happening again. Although the 1953 storm was indeed a low probability event leading to very high storm-induced water-levels, and occurred in combination with spring tide, several arguments are presented that explain why this flood turned into a disaster of such a large scale. Equally, the question is raised whether the disaster could have been prevented. The paper concludes by noting the importance of awareness and preparedness in order to prevent a future storm threat of this scale turning into a disaster of the scope of the Big Flood of 1953.     

Increase or decrease in stability after nucleotomy? Conflicting in vitro and in vivo results in the sheep model

Nucleotomy is a common surgical procedure to treat disc herniations. The potential occurrence of segmental instability after surgery, however, is suspected to necessitate re-operation and fusion. Although in vitro studies support the theory of destabilization after nucleotomy, a prior, in-house animal study contrarily revealed an increase in stability after surgery. To identify which structural compartment of the motion segment is decisive for increased stability after nucleotomy in vivo, the flexibilities of ovine motion segments were measured after different stepwise reductions at the anterior and posterior spinal column. Different test groups were used in which nucleotomy had been performed during surgery in vivo and under isolated in vitro conditions, respectively. In accordance with expectations, in vitro nucleotomy on ovine motion segments significantly increased flexibility. By contrast, nucleotomy significantly decreased flexibility 12 weeks after surgery. After removal of the posterior structures, however, the differences in flexibility diminished. The present results thus suggest that it might not exclusively be the trauma to the intervertebral disc during surgery which is decisive for post-operative stability, but rather adaptive mechanisms in the posterior structures. Therefore, care should be taken to minimize the damage to the posterior structures in the course of the surgical approach, which more likely compromises stability.     

Regulating Zn Deposition via an Artificial Solid–Electrolyte Interface with Aligned Dipoles for Long Life Zn Anode

Aqueous zinc ion batteries show prospects for next-generation renewable energy storage devices.However,the practical applications have been limited by the issues derived from Zn anode.As one of serious problems,Zn dendrite growth caused from the uncontrollable Zn deposition is unfavorable.Herein,with the aim to regulate Zn deposition,an artificial solid–electrolyte interface is subtly engineered with a perovskite type material,BaTiO3,which can be polarized,and its polarization could be switched under the external electric field.Resulting from the aligned dipole in BaTiO3 layer,zinc ions could move in order during cycling process.Regulated Zn migration at the anode/electrolyte interface contributes to the even Zn stripping/plating and confined Zn dendrite growth.As a result,the reversible Zn plating/stripping processes for over 2000 h have been achieved at 1 mA cm^?2 with capacity of 1 mAh cm?2.Furthermore,this anode endowing the electric dipoles shows enhanced cycling stability for aqueous Zn-MnO2 batteries.The battery can deliver nearly 100%Coulombic efficiency at 2 Ag^?1 after 300 cycles.