bluuebunny/crossref_metadata_2025 huggingface dataset:
Association between lipid peroxidation and inflammation in obstructive sleep apnoea
Authors: Minoguchi K. , Yokoe T. , Tanaka A. , Ohta S. , Hirano T. , Yoshino G. , O’Donnell C. P. , Adachi M.
Published: August 2006

In the present study, the authors examined the relationship between lipid peroxidation and inflammation in patients with obstructive sleep apnoea (OSA).

A total of 40 obese patients with OSA were studied, along with 18 obese and 12 lean subjects without OSA. Overnight excretion of 8-isoprostane in urine and serum levels of high-sensitivity C-reactive protein (hsCRP) were measured. In addition, the effects of 3 months’ treatment with nasal continuous positive airway pressure (nCPAP) were studied in 20 obese patients with moderate-to-severe OSA.

Overnight urinary excretion of 8-isoprostane and serum levels of hsCRP were significantly higher in patients with moderate-to-severe OSA compared with patients with mild OSA and obese or lean subjects without OSA. Overnight urinary excretion of 8-isoprostane significantly correlated with apnoea–hypopnoea index, duration of hypoxia during sleep, body mass index, and serum levels of hsCRP in patients with OSA. The severity of OSA was an independent factor predicting the urinary excretion of 8-isoprostane. nCPAP significantly decreased urinary excretion of 8-isoprostane and serum levels of hsCRP.

In conclusion, these results suggest that both obstructive sleep apnoea severity and obesity can independently contribute to elevations in urinary excretion of 8-isoprostane. Therefore, obstructive sleep apnoea may increase the risks of cardiovascular morbidity in obese patients.
Herbal medicines for the treatment of COPD: a systematic review
Authors: Guo R. , Pittler M. H. , Ernst E.
Published: August 2006

The aim of the current study was to systematically assess the effectiveness of herbal medicines in treating chronic obstructive pulmonary disease (COPD).

Randomised clinical trials (RCTs) testing herbal medicines against any type of control intervention in patients with COPD and assessing clinically relevant outcomes were included. The selection of studies, data extraction and validation were performed independently by at least two reviewers. Methodological quality was evaluated using the Jadad score. Effect sizes and their 95% confidence intervals were calculated.

Fourteen eligible RCTs, testing 14 different herbal medicines, were located. Herbal medicines were compared against placebo or no treatment in six trials. Significant intergroup differences for one or more outcome were reported for several herbal medicines includingPanax ginsengandSalvia miltiorrhiza. In seven RCTs, which compared herbal medicines with other herbal medicines, the results were mixed. A single trial compared a herbal medicine (Hedera helixleaf extract) with a conventional treatment (ambroxol tablet) and reported no significant difference between groups. Due to the heterogeneity of the data, statistical pooling was not performed. The median methodological quality score was 2 out of a possible maximum 5.

The effectiveness of herbal medicines for treating chronic obstructive pulmonary disease is not established beyond reasonable doubt. Currently, the evidence from randomised clinical trials is scarce and often methodologically weak. Considering the popularity of herbal medicine among chronic obstructive pulmonary disease patients, rigorously designed studies seem warranted.
Sex differences in the clinical presentation and management of airflow obstruction
Authors: Dales R. E. , Mehdizadeh A. , Aaron S. D. , Vandemheen K. L. , Clinch J.
Published: August 2006

The aim of the present study was to explore differences in the clinical expression, clinical diagnoses and management of airway diseases in a primary-care setting.

Patients aged ≥35 yrs who had ever smoked were enrolled when they presented for any reason to one of eight rural primary-care practices. Respiratory symptom questionnaires and spirometry were administered. In total, 1,034 patients had acceptable and reproducible spirometry, of whom 550 (53%) were males and 484 (47%) were females.

Males smoked more than females (41.2versus29.2 pack-yrs) respectively, and were more likely to have a pre-bronchodilator forced expiratory volume in one second/forced vital capacity <0.70 at 22.4versus11.8%, respectively. However, more females than males reported breathlessness (51.0versus42.8%, respectively), a prior diagnosis compatible with airflow obstruction and taking respiratory medications (23.4versus14.9%, respectively).

In conclusion, the current results suggest that females are more likely than males to report breathlessness and be prescribed respiratory medications independent of differences in the severity of airflow obstruction.
Very long-chain acyl-CoA dehydrogenase deficiency presenting as acute hypercapnic respiratory failure
Authors: Tong M. K. H. , Lam C-S. , Mak T. W. L. , Fu M. Y. P. , Ng S-H. , Wanders R. J. A. , Tang N. L. S.
Published: August 2006

Very long-chain acyl-CoA dehydrogenase deficiency (VLCAD) is a key enzyme catalysing the dehydrogenation of long-chain fatty acids in mitochondrial β-oxidation. VLCAD deficiency is a genetic disorder that commonly presents in infancy or childhood with episodes of hypoketotic hypoglycaemia, cardiomyopathy and liver dysfunction.

The present study reports an 18-yr-old Chinese female who presented with acute hypercapnic respiratory failure and rhabdomyolysis after a period of prolonged fasting and exertion. VLCAD deficiency was confirmed with decreased VLCAD activity in cultured fibroblasts.

The patient completely recovered with supportive care. Pulmonary function tests after the acute episode showed evidence of chronic subclinical respiratory muscle weakness.

In conclusion, this rare metabolic disorder should be considered in patients presenting with unexplained acute respiratory paralysis and failure.
Real Options Identification and Valuation for the Financial Analysis of Product Family Design
Authors: Jiao Jianxin , Lim Ching Moi , Kumar Arun
Published: August 2006

The rationale of product family design has been well recognized by both academia and industries alike. It is important to justify the economic latitude of product families. The traditional valuation approaches based on discounted-cash-flow analysis tend to ignore the upside potentials from managerial flexibility inherent in the product family design process. This paper adopts a real option approach to model product family design as an investment strategy being crafted by a series of options that are continuously exercised to achieve expected returns on investment. The focus is on the identification of real options associated with product family design. In accordance with the real options identified, a valuation framework is developed. To demonstrate the feasibility and potential of the real option framework, a case study of mobile phone vibration motor family design is reported.
Investigation of the Burnishing Force During the Burnishing Process with a Cylindrical Surfaced Tool
Authors: Luo Hongyun , Liu Jianying , Wang Lijiang , Zhong Qunpeng
Published: August 2006

This paper presents a three-dimensional burnishing force model which was studied based on elastic-plastic contact mechanics and elastic-plastic impact mechanics. Effects from different aspects are involved in this model, such as macro- and micro-shape parameters, mechanical properties, physics properties, and burnishing process parameters. From this burnishing force model, a more ideal burnished surface can be obtained by deliberately controlling certain parameters. So it can be said that the burnishing force model obtained is very important for promoting the use of the burnishing process, which can be used effectively to reduce surface roughness and increase surface hardness of a workpiece. A simulation curve is obtained from the model. Burnishing process experiments have been undertaken in which yellow brass H62 was selected as the specimen material and a new cylindrical polycrystalline diamond tool developed by the authors was employed in the burnishing process. The majority of the simulation curves are in good agreement with the experimental curves. It has been found from both theoretical and practical studies that three components of burnishing force increase exponentially with the increase of burnishing depth and the Y dimensional burnishing force is much larger than the other two; this phenomenon is very different from that of the cutting process.
CCATA - A Computer-Aided Angular Tolerance Charting System
Authors: Ji Ping , Xue Jianbin
Published: August 2006

This paper introduces a computer-aided angular tolerance charting (CAATC) system, which can deal with products with both angular features and square-shouldered features. The information needed to construct an angular tolerance chart electronically is described and the data structures used in the system are explained. The principle of angular tolerance charting is concisely depicted through analysing the overall structure of the system. The major functional modules of the system are also presented. Finally, an example is adopted to illustrate how to use the CAATC system.
A Three-Dimensional Transient Model for the Analysis of Thermal History During Laser-Based Grout Removal
Authors: Minami K , Crouse P L , Li L
Published: August 2006

Previous studies into the use of high-power diode lasers (HPDLs) for the removal of unwanted grout between tiles revealed the dominant cause of the material removal to be thermally induced chemical reactions occurring within the material during the process. In this work a simple, easily programmable, three-dimensional, finite difference numerical model for the laser-based grout removal process is presented. The primary aim of the analysis is to calculate the temperature profile inside the grout, and thus to predict the material phase and the resultant geometry of the volume removed as a result of continuous-wave HPDL treatment. The effects of varying laser power and speed using different laser beam shapes are examined over the entire range of the heating cycle. The calculated results are compared with experimental results, showing reasonable agreement between removal depths obtained experimentally and those predicted by the model.
AA6082-T6 Friction Stir Welded Joints Fatigue Resistance: Influence of Process Parameters
Authors: Cirello A , Buffa G , Fratini L , Pasta S
Published: August 2006

In the paper the results of a wide range of experiments on friction stir welding (FSW) of aluminium alloys are reported. In particular, the AA6082-T6 butt joints fatigue resistance was investigated by varying the most relevant process parameters. In addition, a revolutionary pitch was utilized in order to investigate the effects of the tool rotating speed and the tool feed rate. Observations of the fracture insurgence were developed for different levels of applied load.
The Implications of Organizational Culture and Trust in the Working of Virtual Teams
Authors: Dani S S , Burns N D , Backhouse C J , Kochhar A K
Published: August 2006

The research described in this paper is concerned with examining trust issues in global teams and whether there are any implications for trust in respect to the cultural orientation of firms. Trust is the individual's (or group's) belief that another individual (or group) makes good faith efforts to behave in accordance with any commitments both explicit and implicit. This research was carried out as part of a collaborative project between Loughborough and Aston Universities. In this research it was decided to measure whether there was a relationship between perceived levels of trust in the organization and organizational culture as depicted by Cameron and Quinn in the working dynamics of virtual organizations. The research investigated the issue of trust in a number of business situations and showed that there does appear to be a relationship between trust and cultural orientation of firms for the working of virtual teams.
On the Analysis of the Expansion and Reduction of Thin-Walled Tubes Using a Die
Authors: Alves M L , Gouveia B P P , Rosa P A R , Martins P A F
Published: August 2006

The production of sound thin-walled tubular parts by expansion and reduction using a die is generally limited to components having geometrical features within a compact range. Basic design rules, relevant to process and die design are mainly derived from the accumulated experience of both manufacturers of tubular parts and suppliers of machine tools. However, gaps of knowledge can still be found in understanding the influence of process parameters on material flow and in providing an adequate description of the modes of deformation that are associated with the formability limits induced by ductile fracture, wrinkling, and buckling. The aim of the present paper is to extend the actual knowledge on the expansion and reduction of thin-walled tubes using a die by means of a comprehensive theoretical and experimental investigation. The theoretical investigation is supported by axisymmetric and three-dimensional numerical simulations based on the finite element flow formulation. The experimental work, performed on AA6060 aluminium alloy tubes, consisted of specially designed tests that were carried out under laboratory-controlled conditions with the intention of supporting and validating the overall investigation.
The Role of Social Relationships in Improving Product Development Decision Making
Authors: Morton S C , Brookes N J , Dainty A R J , Backhouse C J , Burns N D
Published: August 2006

The quality of decision making in product development (PD) is dependent upon the designer's ability to optimize conflicting needs. However, optimization is unlikely to succeed when based on inaccurate or erroneous information. Given that provision of accurate information frequently lies beyond the designer, decision making is dependent upon effective optimization and a timely flow of accurate information. The present paper explores informal organizational approaches to improving information flow for decision making. It presents an empirical study of relationships in two UK engineering companies and finds significant correlation between the effectiveness of these relationships and the trust, respect, and loyalty that they exhibit during PD. It further identifies the impact of relationship longevity, commonalty in background, and the wider social context of relationships. It concludes by examining the potential extendibility of the findings and the potential for further research to identify interventions that can assist management to enhance the relationships of product developers.
Application of Response Surface Methodology for Predicting Flank Wear in Turning Operation
Authors: Thangavel P , Selladurai V , Shanmugam R
Published: August 2006

Wear has drastic effects on flank wear during the turning process, which affects tool life and the surface roughness of the finished component. The aim of this study was to evaluate the impact of factors such as cutting speed, feed rate, and depth of cut on flank wear of a highspeed steel (HSS) cutting tool during the turning process of a mild steel component. A mathematical model was developed relating flank wear and the main factors such as cutting speed V, feed rate F, and depth of cut T. Response surface methodology (RSM) was used to develop the mathematical model and the model was checked for adequacy by regression analysis. Main and interaction effects of the control factors on flank wear are presented in graphical form, which helps in selecting quickly the process parameters to achieve the desired quality of machining surface by way of controlling the wear of the cutting tool. It is a very important technique to measure the tool wear on-line, so that the tool can be changed when its profile is lost or it produces a poor quality, which is not acceptable.
Towards the Automatic Interpretation of Ultrasonic Non-Destructive Testing Data through the Application of Image-Thresholding and Region-Growing Segmentation
Authors: Asemota E , Gallagher S , Lees B , Cochran S
Published: August 2006

To interpret ultrasonic non-destructive testing (NDT) B-scan images automatically, regions of interest (ROI) within the image must be identified, extracted, and interpreted. Image segmentation can be utilized for identifying constituent ROIs within images and their extraction for further analysis.

Image segmentation is achieved either by applying edge detection transforms (EDTs), image thresholding (IT), or region growing (RG). Although EDTs can be applied without prior knowledge of the image, they are computationally expensive. By contrast, IT involves fewer computational processes but often requires some prior knowledge of the image and the selection of an appropriate threshold. However, B-scan images contain a background from which a threshold for segmentation can be established. Application of a suitable RG technique to the resultant image yields ROIs which can then be analysed and interpreted as being either defects or not.

This paper outlines the development of a software system that utilizes IT and RG in order to extract ROIs within a B-scan image. Once extracted, these can be analysed within an automatic interpretation system for NDT data.
Optimal Die Design for Three-Dimensional Porthole Extrusion Using the Taguchi Method
Authors: Wang Shui To , Lee Rong Shean , Li Hsiu Ying , Chen Chi Hang
Published: August 2006

Empirical knowledge and the trial-and-error method are still common design approaches used in the extrusion industry. However, the service life of three-dimensional extrusion dies is generally unstable and extremely short, especially for high-strength aluminium extrusions, which clearly increases production cost and lowers efficiency. This paper proposes a method for establishing optimal die design for three-dimensional extrusions using the Taguchi method and the finite element method (FEM). Taguchi's orthogonal array is applied to plan the simulation of FEM. After Taguchi's response analysis, the influence of each factor on the die stress was understood and an optimum design was obtained.
Errors in the r value when based upon total strain measurements
Authors: Rees D W A
Published: August 2006

The r value appears in many theoretical accounts of plastic anisotropy. In the interpretation of r as a formability parameter, three methods have been employed to establish errors that arise when r is found from using total strains rather than plastic strains. Inaccuracies are likely to arise where fully instrumented uninterrupted tensile testing is used for rapid quality control of sheet stock supply. Here, the calculations for r and those for other mechanical properties, including strength, ductility, and the n value, are usually fully automated, their values being displayed at the end of the test. This procedure foregoes the greater time consumed with the preferred procedure involving a repeated loading-unloading from within the plastic region. With unloading, the elastic strain recovers, allowing r to be found correctly as a ratio between its two components of plastic strain. Without unloading, the implication is that the r value has been based upon total strain. Certainly, it is traditional within the metal-forming industry to calculate the hardening exponent n from total strains. It is, of course, possible to calculate the elastic strain to be removed at a particular stress level, from the elastic constants, but this is unlikely to be incorporated into a procedure where elastic strains are regarded as negligibly small. The present analyses confirm that this would be true for the larger strains attained in forming a product from sheet steel, the error in r being less than -1 per cent beyond 10 per cent strain. However, it appears that the error accelerates with diminishing strain. For example, an error in r of -3 per cent applies to a 1 per cent total strain. Moreover, when elastic and plastic strains reduce further to a comparable magnitude in microstrain, the error in r rises to -15 per cent. The latter has a bearing upon other areas of plastic anisotropy, including the elastic-plastic analyses of structures and the determination of the subsequent yield surface.
Transformational Leadership and Organizational Culture: The Situational Strength Perspective
Authors: Masood S A , Dani S S , Burns N D , Backhouse C J
Published: August 2006

This paper provides a new leadership alignment model incorporating various concepts focusing on leadership styles, organizational leadership, and situational strength. These concepts are brought together to introduce a leadership model, which looks not only at individual leadership and the effect of that on the organization but also at an organization as a system and how leadership behaviour and culture in individual departments or sections in an organization can be explained. Based on the work of Podsakoff et al., a 23-item measure of transformational leadership questionnaire was employed to evaluate transformational leaders. 339 followers from five manufacturing companies were asked to complete the questionnaire about their leaders and it was analysed to identify transformational leaders. The 76 manufacturing leaders then completed the organizational culture assessment instrument and a situational strength questionnaire, which was used to study the hypothesis.
Rapid Calculation of the Pressures and Clearances in Rough, Elastohydrodynamically Lubricated Contacts Under Pure Rolling. Part 1: Low Amplitude, Sinusoidal Roughness
Authors: Hooke C J , Li K Y
Published: August 2006

Modern elastohydrodynamically lubricated (EHL) solvers allow the calculation of the pressures and clearances in rough EHL contacts. However, the process is time consuming and the results give little insight into the physical behaviour of the system. The length of calculation also makes these methods unsuitable for use as a design tool. The investigation of the behaviour of low amplitude, sinusoidal roughness in EHL contacts provides greater understanding of the processes involved. The results also allow the effects of surface roughness to be examined rapidly. This suggests that it may be possible to develop the approach and create a ‘real-time’ design process for the analysis of different surface roughnesses under a range of operating conditions.
Buckling of Non-Uniform Columns with an Arbitrary Number of Cracks
Authors: Li G Q , Li Q S , Wu Z
Published: August 2006

The governing differential equation for buckling of a non-uniform column is expressed in the form of bending moment. The special solutions for 14 types of non-uniform columns are derived from the governing equation. Using a rotational spring and a hinge connection to describe the local flexibility induced by a crack in the column yields the eigenvalue equation for buckling. The main advantage of the proposed method is that the eigenvalue equation for buckling of a non-uniform column with an arbitrary number of cracks, any kind of two end supports, and an arbitrary number of rotational and translational spring supports at intermediate points can be conveniently determined from a second-order determinant based on the fundamental solutions and recurrence formula developed in this paper. As a consequence, the decrease in the determinant order as compared with previously developed procedures simplifies the analysis. A numerical example is given to illustrate the application of the proposed method and to study the effect of cracks on the critical buckling force of a non-uniform column.
Properties of Titanium Dental Implant Models Made by Laser Processing
Authors: Laoui T , Santos E , Osakada K , Shiomi M , Morita M , Shaik S K , Tolochko N K , Abe F , Takahashi M
Published: August 2006

This article discusses the influence of various process parameters on the characteristics of titanium dental implants made by laser-forming techniques involving both laser sintering and laser melting. The implant models have a porous surface structure to increase bone-osseointegration and a compact core to provide the required mechanical strength. Models in the shapes of rod and cone were built using a continuous wave (CW) laser yielding a threshold compressive force as high as 1000 N after a postsintering treatment in a vacuum furnace at 1200°C for 1.5 h. Using selective laser melting with the pulsed laser, the best parameters were found to be: scan speed of 6 mm/s, laser peak power of 1 kW, and hatching pitch of 0.4 mm yielding a tensile strength of 300 MPa and torsional fatigue strength of 100 MPa. To improve the surface wear resistance of the titanium models, laser gas nitriding using CW Nd:YAG laser was applied. The formed TiN layers had a sponge-like structure with a thickness varying from 30 to 60 μm. The hardness measured at ε20 μm from the surface varied from 1000 to 600 HV by changing the scan speed from 1 to 16 mm/s.
Jet Heat Transfer in the Vicinity of a Rotating Grinding Wheel
Authors: O'Donovan T S , Murray D B , Torrance A A
Published: August 2006

Impinging jets are known as a method of achieving high convective heat transfer coefficients. One potential application of impinging jet heat transfer is the air jet cooling of a grinding process. A grinding process generates heat that must be dissipated to avoid thermal damage. To date, this has been achieved using flood cooling with a traditional coolant such as an oil and water mixture; however, using a jet of air in its place has obvious environmental and economic benefits. For a range of grinding test configurations, results are presented of the convective heat transfer from the workpiece, along the notional plane of cut, and of the air flow velocity in a two-dimensional plane perpendicular to the workpiece. It has been shown that a boundary layer that develops around the rotating grinding wheel has the effect of displacing a peak in the distribution of the local heat transfer coefficient from the notional arc of cut. To effectively cool the grinding zone, therefore, it is necessary to penetrate this boundary layer and this can only be achieved when the jet velocity is substantially greater than the tangential velocity of the wheel.
Crease Stiffness and Panel Compliance of Carton Folds and Their Integration in Modelling
Authors: Cannella F , Dai J S
Published: August 2006

This paper investigates the stiffness characteristics of creases and panels of a carton, and their integrated effect on the carton during folding and manipulation in packaging, reveals the resistive moment resulting from carton creases and identifies the force required for folding cartons.

The study starts from the residual moment of carton creases and its effects on carton panels when erecting a carton section. By characterizing stiffness of both creases and panels, an analytical model is developed and compared with numerical results from finite-element analysis. The study then extends to a whole carton with a crush-lock closure base. By modelling the base as a four-bar mechanism with guiding linkages, a kinematic model of the carton is established and the residual moment and forces are obtained. The paper further reveals the carton elasticity property and the non-linearity deformation that contributes to modelling in a case study.
Exploration Study of Multifunctional Metallic Nanocomposite Utilizing Single-Walled Carbon Nanotubes for Micro/Nano Devices
Authors: Chen Quanfang , Chai Guang , Li Bo
Published: August 2006

Carbon nanotubes (CNTs) are excellent multifunctional materials in terms of mechanical robustness, thermal, and electrical conductivities. These multifunctional properties, as well as the small size of the structures, make CNTs ideal building blocks in developing nanocomposites. However, the matrix materials and the fabrication processes are critical in achieving the expected multifunctional properties of a CNT-reinforced nanocomposite. This paper has proved that electrochemical co-deposition of a metallic nanocomposite is a good approach for achieving good interfacial bonding between CNTs and a metallic matrix. Good interfacial bonding between a single-walled carbon nanotube (SWCNT) and a copper matrix has been verified by enhanced fracture toughness (increased stickiness) and a shift in the Raman scattering spectra. For the Cu/SWCNT nanocomposite, the radial breath mode (RBM) has disappeared and the tangential or G-band has shifted and widened, which is an indication of better energy transport.
Screening Libraries of Circularly Permuted Proteins by Phage Display to Manipulate Protein Topographies
Authors: Eteshola E , Van Valkenburgh C. D. , Merlin S , Rowold E , Adams J , Ibdah R , Pegg L. E. , Donelly A , Klover J , Lee S. C.
Published: August 2006

Active biomolecules, particularly proteins, are increasingly used in functional nanostructures. For some applications, native proteins (i.e. proteins as they occur in nature) are not effective nanodevice components because distances between the ends of the protein and some protein functional domain exceeds some critical nanoscale distance. This problem occurs in sensing architectures that detect energy or electron transfer where native protein sizes exceed critical distances for quantum energy transfer or exceed the thickness of shielding layers of counter ions, and might be addressed by alterations of protein topography. This work describes a high-throughput recombinant DNA method rapidly to identify functional circularly permuted (cp) protein variants. When appended to a sensing device or other nanometer scale distance-dependent device using chemoselective conjugation methods, cp variants offer a potential strategy to address the nanometer size limitations of native proteins.
Study of the Combined Temperature, Rate, and Size Effects on the Tungsten Crystalline Block Strength
Authors: Shen L , Chen Z
Published: August 2006

Understanding the responses of materials of different sizes at various temperatures and strain rates is essential to evaluating the integrity and safety of microelectromechanical and nanoelectromechanical system devices under extreme loading conditions. Although material properties are size, rate, and temperature dependent in nature, little has been achieved in investigating the combined specimen size, loading rate, and temperature effects on the material properties. Based on the experimental and computational capabilities available, therefore, an attempt is made in this paper to formulate a hypersurface in spatial, temporal, and thermal domains to predict the combined size, rate, and temperature effects on the material properties of a tungsten crystalline block. It appears from the preliminary results that the proposed procedure might provide an effective means of bridging different spatial and temporal scales in a unified multi-scale modelling framework at different temperatures.
On Optimality Criteria for Age Replacement
Authors: Coolen-Schrijner P , Coolen F. P. A.
Published: August 2006

Age replacement is a well-known topic in the literature of operational research and reliability. Traditionally, the probability distribution of a unit's failure time is assumed to be known, and the cost criterion is derived via the renewal reward theorem, which implicitly assumes that the same preventive replacement strategy will be used over a very long period of time. As an alternative, a one-cycle criterion can be used, aiming at minimization of costs per unit of time only over the period that one unit is in place. These two criteria are discussed and possible alternatives are also considered. Recently, the authors have presented a non-parametric predictive approach to age replacement, which is based on rather minimal assumptions for the failure time distributions, and provides full flexibility to the information from the process. The main conclusions from this research, where both the renewal criterion and the one-cycle criterion were also considered, are summarized. Further aspects related to age replacement are discussed, highlighting several interesting topics for further research.
Qualitative Analysis of Complex Modularized Fault Trees Using Binary Decision Diagrams
Authors: Remenyte R , Andrews J. D.
Published: August 2006

Fault tree analysis is commonly used in the reliability assessment of industrial systems. When complex systems are studied conventional methods can become computationally intensive and require the use of approximations. This leads to inaccuracies in evaluating system reliability. To overcome such disadvantages, the binary decision diagram (BDD) method has been developed. This method improves accuracy and efficiency, because the exact solutions can be calculated without the requirement to calculate minimal cut sets as an intermediate phase. Minimal cut sets can be obtained if needed.

BDDs are already proving to be of considerable use in system reliability analysis. However, the difficulty is with the conversion process of the fault tree to the BDD. The ordering of the basic events can have a crucial effect on the size of the final BDD, and previous research has failed to identify an optimum scheme for producing BDDs for all fault trees. This paper presents an extended strategy for the analysis of complex fault trees. The method utilizes simplification rules that are applied to the fault tree to reduce it to a series of smaller subtrees whose solution is equivalent to the original fault tree. The smaller subtree units are less sensitive to the basic event ordering during BDD conversion. BDDs are constructed for every subtree. Qualitative analysis is performed on the set of BDDs to obtain the minimal cut sets for the original top event. It is shown how to extract the minimal cut sets from complex and modular events in order to obtain the minimal cut sets of the original fault tree in terms of basic events.
Failure Bunching Phenomena in Electric Power Transmission Systems
Authors: Billinton R , Singh G , Acharya J
Published: August 2006

The physical environment in which a component resides can have a significant effect on the resulting reliability of the system. This is particularly true in electric power systems containing overhead transmission lines. Extreme weather conditions can create significant increases in transmission element stress levels leading to sharp increases in the component failure rates. The phenomenon of increased transmission line failures during bad weather is generally referred to as ‘failure bunching’. This condition should not be misconstrued as a common mode failure. This is an entirely different phenomenon and one that is important for multi-circuit transmission lines on single tower structures. This paper illustrates the inclusion of weather conditions in the reliability analysis of parallel redundant systems. A series of weather models are presented with application to electric transmission lines. The reliability effects of incorporating common mode failures in multi-circuit tower structures and independent events incorporating normal, adverse, and major adverse weather considerations in separated parallel line configurations are illustrated and examined.

The applications described in this paper are to electric power transmission lines. The concepts of stress related failure bunching and common mode failures are, however, applicable to a wide range of engineering systems.
A Note on the Concept of Risk Aversion in Safety Management
Authors: Abrahamsen E. B. , Aven T , Sandøy M
Published: August 2006

Many safety people use the term risk aversion as an argument for some specific decisions under uncertainty. The main purpose of this note is to draw attention to and discuss this practice. They are using the wrong term. Risk aversion is not reflecting what they would like to express. The main reason for investing in safety is not risk aversion, but the desire to protect some values in the face of uncertainties: the thinking is cautionary. Investment in safety is to reduce uncertainty and provide assurance if a hazardous situation should occur.
On Zero-Failure Testing for Bayesian High-Reliability Demonstration
Authors: Coolen F. P. A. , Coolen-Schrijner P
Published: August 2006

Recent results are summarized on the required testing of a system, in order to demonstrate a level of reliability with regard to the system's use in a process after testing. It is explicitly assumed that testing reveals zero failures, which is realistic in situations where high reliability is required and where failures during testing lead to redesign of the system. Several related aspects are discussed, including the choice of prior distribution, what to do if failures do occur during testing, and possibilities to take dependencies between tasks into account. Throughout, it is emphasized that, for reliability demonstration, one should try not to rely too much on mathematical assumptions that cannot be justified by the data, which gives particular restrictions owing to the nature of data from zero-failure tests. All of these topics raise interesting questions for future research.
On Assessing the Reliability and Availability of Marine Energy Converters: The Problems of a New Technology
Authors: Wolfram J
Published: August 2006

There is now considerable interest in marine renewable energy both in the UK and elsewhere in the world with the growing recognition that fossil fuel supplies are finite and further increases in carbon gas emissions will hasten climate change. A major factor in the viability of any potential wave or tidal energy device (marine energy converter (MEC)) is its reliability and availability. However, as for any new technology, this is difficult to predict in advance with confidence. This paper describes the issues that must be addressed to assess the reliability and availability of MECs. It starts with a brief overview of the characteristics of the principal types of wave and tidal energy converters and a review of earlier work on estimating reliability for wave energy converters. It is shown that MECs have many subsystems and components in common with one another and with other existing land-based and marine systems. The ways in which experience with existing systems may be adapted to predict reliability and availability for MECs are discussed and a new embryonic database for MECs is outlined. The choice of distribution for the time to failure of MEC components is discussed and an argument is advanced for the use of the log-normal distribution. The availability of MECs is affected very much by the environment in which they operate and the maintenance strategy adopted. The effects of environment and location upon maintainability and hence availability are described and how availability may be modelled is discussed. Finally the need for a framework for assessing the reliability and availability of MECs and other related issues are discussed.
A Comparison of Modelling Approaches for the Time-Limited Dispatch (TLD) of Aircraft
Authors: Prescott D , Andrews J. D.
Published: August 2006

The time-limited dispatch (TLD) of aircraft allows operators efficiently to meet certification requirements. In order to show that these requirements are met it is necessary to model the aircraft systems to which TLD is being applied. Currently, variations of fault tree analysis and Markov analysis are commonly used. However, in order to apply either of these methods, a number of assumptions are made to assist in the analysis. Monte Carlo simulation (MCS) is presented here as an alternative method of demonstrating the required level of system reliability. A simple system is analysed using a time-weighted average approach, a reduced fault state Markov approach, and an MCS approach. MCS is seen to offer benefits when modelling the application of TLD to a simple system that could also be seen in the modelling of the application of TLD to real aircraft systems.
Synthetic Photochemistry. LVIII. Intramolecular Photocycloaddition of 2-Alkenyl-6-methyl-4H-1,3-dioxin-4-ones
Authors: Takeshita Hitoshi , Cui Ying-She , Kato Nobuo , Mori Akira , Nagano Yoshiaki
Published: August 2006

2-Alkenyl-6-methyl-4H-1,3-dioxin-4-ones, adducts of diketene to alkenals or alkenones, are useful synthons which are applicable to photocycloadditions to construct multiply-functionalized alicyclic compounds via stereoselective intramolecular path. Some of the cage-shaped photoproducts showed extraordinary spectroscopic features.
Modification of α-Chymotrypsin by Bromomethyl Naphthyl Ketones and Behavior of Reporter Groups in the Active Site
Authors: Sakurai Tadamitsu , Kageyama Akihide , Hayashi Hisayoshi , Inoue Hiroyasu
Published: August 2006

The reaction of α-chymotrypsin (ChT) with bromomethyl 1-naphthyl ketone (1-BNK) or with bromomethyl 2-naphthyl ketone (2-BNK) took place at the active site causing inactivation of the enzyme according to second-order kinetics. In addition to this finding, a comparison of the absorption spectrum of 2-BNK-modified ChT (2-BNK–ChT) with those of native ChT and the model dimethyl(2-naphthoylmethyl)sulfonium bromide (2-NSS) at low pH revealed that the alkylating agent, BNK, reacts with methionine-192 on ChT in a 1 : 1 stoichiometric ratio. Evidence for the existence of BNK-derived reporter groups at the enzyme active site came from the observation of (1) positive induced circular dichroism bands of these groups and of (2) pronounced absorption spectral changes of the 2-BNK–derived pendant on denaturation of the alkylated enzyme with guanidine hydrochloride at pH 7.0. From the pH dependence of the absorption spectra of the modified enzymes and the model sulfonium salts, we determined the pKa values of 1-BNK–ChT, 1-NSS, 2-BNK–ChT, and 2-NSS to be 6.6, 7.5, 5.2, and 8.4 at 25 ± 1 °C, respectively. The much larger difference in pKa between 2-BNK–ChT and 2-NSS (ΔpKa = 3.2) compared with that between 1-BNK–ChT and 1-NSS (ΔpKa = 0.9) was explained in terms of stabilization of the 2-BNK-derived ylide pendant due to a configurationally rigid hydrogen-bonding interaction between the ylide carbonyl oxygen atom with a negative charge and the serine hydroxyl group located near the substrate binding site of ChT. Supporting evidence for this interpretation was obtained from solvent effects on the absorption spectra of model compounds as well as pH effects on the remaining activity of the alkylated enzymes.
Effects of Alcoholic Solvents on the Formation of Cyclohexanones in the Hydrogenation of Phenols over Pd–C Catalysts
Authors: Higashijima Michio , Nishimura Shigeo
Published: August 2006

The catalytic hydrogenation of phenol and cresols (methylphenols) with commercial Pd on active carbon (Pd–C) and acid-treated Pd–C (Pd–C–A) has been studied kinetically in t-pentyl alcohol (t-PeOH) and cyclohexane as solvents under 5.0 MPa hydrogen pressure at 120 °C. With both of the catalysts the maximum yields of the cyclohexanone intermediates as well as the hydrogenation rates of the phenols decreased markedly in t-PeOH, compared with hydrogenation in cyclohexane. With Pd–C–A in t-PeOH the decrease in the yields of cyclo-hexanone intermediates was shown to be due only to the increase in the relative reactivity of the cyclohexanones to phenols (K). On the other hand, with Pd–C the marked decreases were attributed not only to the increases in the values of K but also to the decreases in the selectivity for the formation of the ketone intermediates (f). The rates decreased in the order phenol > m- > p- > o-cresol, irrespective of the catalysts and solvents. The relative reactivities and strengths of the adsorption of phenol to isomeric cresols were evaluated by both individual and competitive hydrogenation. It is suggested that the phenols are adsorbed on the catalysts both at the benzene nucleus and the hydroxyl group, and that the remarkable effects of alcoholic solvents over basic Pd–C result from the interaction of the hydroxyl groups as phenoxide ions with alcoholic solvents which may weaken adsorption at the phenoxide ions.
Infrared Spectroscopic Observation of Adsorbed CO Intermediately Formed in the Electrochemical Reduction of CO2 at a Nickel Electrode
Authors: Hori Yoshio , Koga Osamu , Aramata Akiko , Enyo Michio
Published: August 2006

A nickel electrode surface during electroreduction of CO2 in phosphate buffer solution was studied by in situ infrared spectroscopy. SNIFTIRS (subtractively normalized interfacial Fourier transform infrared spectroscopy) technique showed the presence of adsorbed CO on the electrode surface between −0.4 and −0.8 V vs. NHE in CO saturated solution. The adsorbed CO was bonded to the electrode in linear and bridged fashions. Linear and bridged adsorbed CO molecules were also detected on the electrode during the electroreduction of CO2. Linear CO disappeared at relatively negative potential (−0.8 V). Since the reduction of adsorbed CO proceeds below −1.0 V, the electroactive species in the reduction of CO is presumed to be bridged type CO.
Reactions of Hydridoruthenium(II) Complexes with Alkyl Allylic Sulfides
Authors: Hiraki Katsuma , Fuchita Yoshio , Kawabata Hirosuke , Iwamoto Koji , Yoshimura Takashi , Kawano Hiroyuki
Published: August 2006

[RuClH(CO)(PPh3)3] (1) reacted with alkyl allyl sulfides at 10–25 °C to give insertion products, [Ru(CH2CH2CH2SR)Cl(CO)(PPh3)2] (R = CH3, 2; R = CH2C6H5, 3; and R = CH2CH=CH2, 4). Complexes 2–4 exhibited temperature-dependent NMR spectra above −40 °C, indicating that rapid exchange occurred between two structural isomers owing to inversion of the alkyl group upon the coordinated sulfur stom. Upon heating at 67 °C, 2 was converted into a binuclear complex, [Ru2(μ-Cl)Cl(μ-H)(μ-SCH3)(CO)2(PPh3)3], evolving propylene. Complex [RuClH(CO)(dppe)(PPh3)] (7) [dppe = 1,2-bis(diphenylphosphino)ethane] reacted with allyl methyl sulfide at 110 °C to afford [Ru2Cl2(μ-SMe)2(CO)2(dppe)2] (8), evolving propylene.
X-Ray Structure and Conformational Analyses of Cobalt(III) Complexes Containing 1,3-Propanediamine and 1,4-Butanediamine
Authors: Kurachi Saeko , Ohba Shigeru
Published: August 2006

Crystal structures of octahedral cobalt(III) complexes containing diamines, NH2 (CH2)n NH2 with n = 3 or 4 (abbreviations are tn and tmd, respectively), were determined by X-ray analysis. In crystals of [Co(tn)(tmd)2] Cl3, (1), the tn chelate ring takes skew-boat form, and the conformation of the complex is lel  lel2. In crystals of [Co(tn)2(tmd)]Br3·2.7H2O, (2), both two independent complex cations take syn-chair2  lel configuration. Molecular mechanics calculation indicated that the six-membered tn chelate ring may take skew-boat form in a crowded system to reduce the steric repulsions between the chelate rings, although the tn chelate ring originally prefers the chair form.
Lanthanoids in Organic Synthesis. I. The Novel Reduction of Carboxylic Acids with Samarium Diiodide-Base System
Authors: Kamochi Yasuko , Kudo Tadahiro
Published: August 2006

Aromatic and aliphatic carboxylic acids were rapidly reduced with samarium diiodide by the addition of base in the presence of protic solvent at room temperature to the corresponding alcohols. Sodium benzoate was similarly reduced with samarium diiodide in the presence of H2O in a good yield. In the similar reactions of benzoic acid derivatives bearing carboxyl, formyl, carbamoyl, methoxyl, and chloro groups, these functional groups were also reduced to the corresponding alcohol or amine derivatives. Interestingly, the carboxyl and formyl groups of benzoic acids were partly reduced into the methyl group.
Protein Synthesis Using S-Alkyl Thioester of Partially Protected Peptide Segments. Synthesis of DNA-Binding Protein of Bacillus stearothermophilus
Authors: Hojo Hironobu , Aimoto Saburo
Published: August 2006

Using partially protected peptide thioesters as building blocks, we synthesized HU-type DNA-binding protein of Bacillus stearothermophilus. Four peptide segments, Boc–[Lys(Boc)3]–HBs(1–15)–SCH2CH2CONH2, iNoc–[Lys(Boc)18,19,23,38]–HBs(16–39)–SCH2CH2CONH2, iNoc–[Lys(Boc)41,59]–HBs(40–60)–SCH2CH2CONH2, [Lys(Boc)75,80,83,86,90]–HBs(61–90) were prepared using peptides obtained by a solid-phase method. A partially protected peptide thioester was condensed to a peptide with a free amino group by converting the thioester to the corresponding active ester in the presence of silver ions and N-hydroxysuccinimide. Finally, highly pure synthetic HBs(1–90) was obtained.