bluuebunny/crossref_metadata_2025_split huggingface dataset:
Modeling crack propagation path of anisotropic rocks using boundary element method
Authors: Ke Chien‐Chung , Chen Chao‐Shi , Ku Cheng‐Yu , Chen Chih‐Hao 
Published: December 2008

AbstractIn a cracked material, the stress intensity factors (SIFs) at the crack tips, which govern the crack propagation and are associated with the strength of the material, are strongly affected by the crack inclination angle and the orientation with respect to the principal direction of anisotropy. In this paper, a formulation of the boundary element method (BEM), based on the relative displacements of the crack tip, is used to determine the mixed‐mode SIFs of isotropic and anisotropic rocks. Numerical examples of the application of the formulation for different crack inclination angles, crack lengths, and degree of material anisotropy are presented. Furthermore, the BEM formulation combined with the maximum circumferential stress criterion is adopted to predict the crack initiation angles and simulate the crack propagation paths. The propagation path in cracked straight through Brazilian disc specimen is numerically predicted and the results of numerical and experimental data compared with the actual laboratory observations. Good agreement is found between the two approaches. The proposed BEM formulation is therefore suitable to simulate the process of crack propagation. Copyright © 2008 John Wiley & Sons, Ltd.
Urinary incontinence among institutionalized oldest old Chinese men in Taiwan
Authors: Chen Yi‐Ming , Hwang Shinn‐Jang , Chen Liang‐Kung , Chen Der‐Yuan , Lan Chung‐Fu 
Published: December 2008

AbstractAimsTo explore prevalence and related factors for urinary incontinence (UI) among the oldest old institutionalized Chinese men in Taiwan. MethodsAll residents living in Banciao Veterans Care Home were invited for study. UI was defined as urinary leakage at least once weekly. Additional data items from the Minimum Data Set (MDS Nursing Home Chinese Version 2.1) were used to explore impact associated with physical function, cognitive status and quality of life (social engagement, SocE). Depressive symptoms were screened by the Short Form Geriatric Depression Scale. ResultsData from 594 male residents (mean age: 80.9 ± 5.3 years) were analyzed. Among all study subjects, 92.8% were functionally independent, 20.4% had certain cognitive impairment and 8.2% had depressive symptoms. The prevalence of UI in the Banciao Veterans Care Home was 10.1%. Compared with residents without UI, subjects with UI had poorer physical function, cognitive status, and more depressive symptoms. The mean SocE score was 1.5 ± 1.3, and was similar between UI (+) and UI (−) subjects (1.4 ± 1.2 vs. 1.6 ± 1.3, P = 0.411). By multivariate logistic regression, poorer physical functional status, cognitive impairment and depressive symptoms were independent risk factors for UI (P < 0.05). ConclusionsPoorer physical function, poorer cognitive status and depressive symptoms were all statistically significant independent risk factors for UI. However, SocE score (proxy indicator of quality of life) did not differ between subjects with and without UI. Further investigations are needed to evaluate the impact of UI on quality of life among oldest old institutionalized Chinese men in Taiwan. Neurourol. Urodynam. 28:335–338, 2009. © 2008 Wiley‐Liss, Inc.
Impact of urinary incontinence on the psychological burden of family caregivers
Authors: Gotoh Momokazu , Matsukawa Yoshihisa , Yoshikawa Yoko , Funahashi Yasuhito , Kato Masashi , Hattori Ryohei 
Published: December 2008

AbstractAimsThe present study was conducted to assess the impact of urinary incontinence on the psychological burden of family caregivers providing care to disabled family members with urinary incontinence.Materials and MethodsThis survey was conducted using an Internet panel for family caregivers in Japan, consisting of 7,316 members. We requested the members to respond to an online questionnaire to assess the impact of urinary incontinence on the burden of caregivers. The questionnaire included basic characteristics, and the Japanese version of the Zarit Caregiver Burden Interview (ZBI) comprising 22 questions related to the impact of the patient's disabilities on the burden of their caregivers. Additionally, the participants were asked to include the level of care need, ranging from 0 to 5 according to the grade of disability of the cared individuals.ResultsRelevant data obtained from 757 caregivers were analyzed. Of these caregivers, 452 provided care to family members with urinary incontinence (group 1), and 305 provided care to those without urinary incontinence (group 2). The mean total ZBI score was significantly higher in group 1 than in group 2 (mean, 40.7 vs. 34.7, P < 0.001). The difference in the scores for each item was also significant in 20 of the 22 items. With regard to the level of care need, irrespective of the level, the ZBI scores in group 1 tended to be higher than those in group 2.ConclusionsThe present survey demonstrated a negative impact of urinary incontinence on the psychological burden of family caregivers. Neurourol. Urodyn. 28:492–496, 2009. © 2008 Wiley‐Liss, Inc.
Partial bladder outlet obstruction reduces the tissue antioxidant capacity and muscle nerve density of the guinea pig bladder
Authors: de Jongh Rik , Dambros Miriam , Haenen Guido R.M.M. , den Hartog Gertjan J.M. , Bast Aalt , van Kerrebroeck Philip E.V. , van Koeveringe Gommert A. 
Published: December 2008

AbstractAimsReactive nitrogen and oxygen species (RNOS) likely play a role in the development of bladder dysfunction related to bladder outlet obstruction. Antioxidants protect against these free radicals. The aim of our study was to investigate the effect of bladder outlet obstruction on the endogenous antioxidant status of the bladder and to correlate this to bladder structure and function.MethodsIn 16 guinea pigs either a partial outlet obstruction or a sham operation was induced. The contractile responses of detrusor strips to electrical field stimulation (EFS), acetylcholine, potassium, and ATP were monitored 4 weeks after the operation. The nerve density in bladder tissue was determined by using the non‐specific nerve marker PGP 9.5. Separate antioxidants and the total antioxidant status were assessed using the trolox equivalent antioxidant capacity (TEAC) test.ResultsContractile responses of detrusor strips to EFS were for the greater part based on neurogenic stimulation. The nerve‐mediated responses in strips from obstructed bladders were lower compared to the sham group. Obstructed bladders showed a patchy denervation and the nerve density was significantly lower compared to the sham group. The total antioxidant capacity, the glutathione and the glutathione reductase (GR) levels significantly decreased in obstructed bladders compared to the sham group.ConclusionThis study demonstrates that the antioxidant status of guinea pig bladders exposed to outlet obstruction decreased which might be associated with the observed reduction in nerve density. The results strengthen the hypothesis that oxidative stress is involved in the pathophysiology of bladder dysfunction related to obstructed bladders. Neurourol. Urodynam. 28:461–467, 2009. © 2008 Wiley‐Liss, Inc.
The Number of Voiding Radiographs During Cystourethrography in Women With Stress Incontinence or Prolapse Can Be Reduced to Enhance Safety Without Compromising Study Interpretation
Authors: Guild Jeffrey , Takacs Elizabeth , Kircher Stephen , Arbique Gary , Zimmern Philippe E. 
Published: December 2008

AbstractAimBased on a prior study, over 60% of the average radiation dose per cystourethrography (CU) originated from lateral radiograph images (RI). This analysis focuses on the feasibility of decreasing the number of RI without compromising study interpretation.MethodsMaterial and Method: Following IRB approval, all RIs from the initial study in women with incontinence and/or bladder prolapse were assessed at random for reading consistency (inter‐rater reliability (IRR)) and reliability (intra‐rater reliability (IaRR)) by four independent reviewers. Interpretation guidelines on urethral readability were established and 15 repeated RIs tested for IaRR. Two months later, the reviewers selected the best two RIs for each CU with the RI presented in a random order.ResultsFrom 88 CU exams providing 304 RIs, good IRRs for readability (κ=0.82, ICC=0.80) and interpretation (κ=0.60, ICC=0.57) were found between reviewers. Mean IaRR for readable versus unreadable categories was 87% and among readable images was 95% for interpretation. The RIs judged best had a high IRR (κ=0.83, ICC=0.83) and were predominantly from the early and middle phases of the void.ConclusionA high level of agreement was found for urethral readability and interpretation between reviewers of varying experience using pre‐established guidelines. No more than 3 RIs were required for study interpretation and those views were from the early to middle phase of voiding, thus allowing a radiation dose reduction without compromising the quality of the CU exam. Neurourol. Urodynam. 28:385–389, 2009. © 2008 Wiley‐Liss, Inc.
Observations relating to urinary sensation during detrusor overactivity
Authors: Lowenstein Lior , Pham Thythy , Abbasy Shameem , Kenton Kimberly , Brubaker Linda , Mueller Elizabeth R. , Shott Susan , Vardi Yoram , Gruenwald Ilan , FitzGerald Mary P. 
Published: December 2008

AbstractAimsTo describe the temporal relationship between increases in lower urinary tract (LUT) sensation and changes in detrusor and/or urethral pressures measured in real time.MethodsWe reviewed 33 multichannel urodynamic tracings that included a continuous recording of LUT sensation and that demonstrated detrusor overactivity incontinence (DOI) or detrusor overactivity (DO). Four physicians reviewed each urodynamic tracing and reached agreement about the temporal relationship between LUT sensation and detrusor contraction.ResultsMedian age was 60 (36–82) years. Fourteen (42%) had urodynamic diagnoses of mixed incontinence, 18 (55%) had DOI, and 1 (3%) had DO without DOI. We reviewed 119 episodes of detrusor overactivity from the 33 recordings. We found no difference in change in sensation level when comparing DO episodes with DOI episodes or between different urodynamic diagnoses (P > 0.5). There was no dominant temporal pattern seen for the whole group (P = 0.84), that is, there was no evidence that the change in sensation level was more likely to occur before, during, or after DO/DOI episodes. When evaluating the changes in the urethral pressure, the most common pattern seen was an increase in sensation level after a fall in urethral pressure, but no dominant pattern was seen.ConclusionsOur findings suggest that increased LUT sensation during DO/DOI is not reliably caused by measurable alterations in bladder or urethral pressure. Neurourol. Urodyn. 28:497–500, 2009. © 2008 Wiley‐Liss, Inc.
Design and control of agile automated CONWIP production lines
Authors: Hopp Wallace J. , Iravani Seyed M.R. , Shou Biying , Lien Robert 
Published: December 2008

AbstractIn this article, we study the design and control of manufacturing cells with a mix of manual and automated equipment, operating under a CONWIP pull protocol, and staffed by a single agile (cross‐trained) worker. For a three‐station line with one automated station, we fully characterize the structure of the optimal control policy for the worker and show that it is a static priority policy. Using analytical models and extensive simulation experiments, we also evaluate the effectiveness of practical heuristic control policies and provide managerial insights on automation configuration design of the line. This characterization of the worker control policy enables us to develop managerial insights into the design issues of how best to locate and concentrate automation in the line. Finally, we show that, in addition to ease of control and greater design flexibility, the CONWIP protocol also offers higher efficiency and robustness than does the push protocol. © 2008 Wiley Periodicals, Inc. Naval Research Logistics 2009
Lanchester models and the battle of Britain
Authors: Johnson Ian R. , MacKay Niall J. 
Published: December 2008

AbstractWe fit deterministic generalized Lanchester models to daily sortie and loss data from the Battle of Britain. The best fit for the period 14th August to 30th October 1940 is δB ∼ G1.2, δG ∼ G0.9, where B and G are RAF Fighter Command and Luftwaffe sortie numbers, and δB and δG are daily loss numbers, respectively. The data naturally divide into two phases, with losses (as a proportion of overall sortie numbers) much reduced after 15th September. Fits were generally better for the first phase than for the second, and for British losses than for German; in every case the dependence on G is stronger than that on B. Days with higher sortie numbers on average favored the Luftwaffe, whereas the loss‐ratio was not significantly dependent on the force ratio. © 2008 Wiley Periodicals, Inc. Naval Research Logistics 58: 210–222, 2011
Technical note: A computationally efficient algorithm for undiscounted Markov decision processes with restricted observations
Authors: Davis Lauren B. , Hodgson Thom J. , King Russell E. , Wei Wenbin 
Published: December 2008

AbstractWe present a computationally efficient procedure to determine control policies for an infinite horizon Markov Decision process with restricted observations. The optimal policy for the system with restricted observations is a function of the observation process and not the unobservable states of the system. Thus, the policy is stationary with respect to the partitioned state space. The algorithm we propose addresses the undiscounted average cost case. The algorithm combines a local search with a modified version of Howard's (Dynamic programming and Markov processes, MIT Press, Cambridge, MA, 1960) policy iteration method. We demonstrate empirically that the algorithm finds the optimal deterministic policy for over 96% of the problem instances generated. For large scale problem instances, we demonstrate that the average cost associated with the local optimal policy is lower than the average cost associated with an integer rounded policy produced by the algorithm of Serin and Kulkarni Math Methods Oper Res 61 (2005) 311–328. © 2008 Wiley Periodicals, Inc. Naval Research Logistics 2009
Hybrid numerical techniques for the modelling of radiofrequency coils in MRI
Authors: Li Bing Keong , Liu Feng , Weber Ewald , Crozier Stuart 
Published: December 2008

AbstractRadiofrequency (RF) coils for use in MRI can have a significant effect on both the signal‐to‐noise‐ratio of MR images and the specific absorption rate inside the biological sample. In the past, prototypes were constructed and tested to investigate the performance of the RF coils and often required several iterations to achieve an acceptable result. However, with the advancement in computational electromagnetic techniques, RF coil modelling has now become the modus operandi of coil design because it can produce accurate numerical results, thus reducing the time and effort spent in designing and prototyping RF coils. Two hybrid methods –method of moments (MoM)/finite difference time domain (FDTD) and MoM/finite element method (FEM) – for RF coil modelling are presented herein. The paper provides a brief overview of FDTD, FEM and MoM. It discusses the hybridisation of these methods and how they are integrated to form versatile techniques. The numerical results obtained from these hybrid methods are compared with experimental results from prototype coils over a range of operating frequencies. The methods are then applied to the design of a new type of phased‐array coil – the rotary phased array. From these comparisons, it can be seen that the numerical methods provide a useful aid for the design and optimisation of RF coils for use in MRI. Copyright © 2008 John Wiley & Sons, Ltd.
Design of multichannel MAC protocols for wireless ad hoc networks
Authors: Lo Shou‐Chih 
Published: December 2008

AbstractMedium access control (MAC) protocols coordinate channel access between wireless stations, and they significantly affect the network throughput of wireless ad hoc networks. MAC protocols that are based on a multichannel model can increase the throughput by enabling more simultaneous transmission pairs in the network. In this paper, we comprehensively compare different design methods for multichannel MAC protocols. We classify existing protocols into different categories according to the channel negotiation strategies they employ. The common problems that may be encountered in multichannel design are discussed. We then propose a hybrid protocol that combines the advantages of the two methods of a common control channel and a common control period. The simulation results show that our proposed protocol can significantly outperform two representative protocols. Copyright © 2008 John Wiley & Sons, Ltd.
Optimum Steiner ratio for gradient‐constrained networks connecting three points in 3‐space, part I
Authors: Prendergast K. , Thomas D.A. , Weng J.F. 
Published: December 2008

AbstractIt is well known that when there is no gradient constraint, the minimum Steiner ratio for three terminals is achieved with an equilateral triangle, and the ratio is $\sqrt{3} \over 2$. This article shows that in the gradient‐constrained cases, the configuration of three terminals giving the minimum Steiner ratio is also an equilateral triangle. However, there are an infinite number of such triangles with differing orientations in 3‐space. We determine the behavior of the Steiner ratio over all of these equilateral triangles and thereby show that the minimum ratio occurs when the triangle is in the vertical plane with one edge vertical. The minimum ratio tends to $3 \over 4$ as the value of the gradient constraint tends to zero. © 2008 Wiley Periodicals, Inc. NETWORKS, 2009
On irreducible no‐hole L(2, 1)‐coloring of trees
Authors: Laskar Renu C. , Matthews Gretchen L. , Novick Beth , Villalpando John 
Published: December 2008

AbstractWe consider a variant of the channel assignment problem in which frequencies are assigned to transmitters in a way that avoids interference while ensuring that all frequencies within the bandwidth are used. This is modeled as an L(2, 1)‐coloring of a graph which is no‐hole and irreducible in the sense that no color can be replaced with a smaller one. In this article, we show that if the network is any tree other than a star, then frequencies may be assigned in this fashion without increasing the bandwidth; that is, we show that for any such tree T, the inh‐span of T is equal to its span. © 2008 Wiley Periodicals, Inc. NETWORKS, 2009
Lower bounding techniques for the degree‐constrained network design problem
Authors: Şahin Güvenç , Ahuja Ravindra K. 
Published: December 2008

AbstractA typical network design problem consists of identifying a subnetwork of a given network that satisfies a set of constraints and minimizes the cost of flow. We consider degree‐constrained network design problems where we specify an upper limit on the number of arcs built at each node. We propose two lower bounding techniques using the concept of lower planes. The first lower bound is based on a known lower plane for network design problems; our second lower bound is stronger than the first, yet has the same polynomial computational complexity. We illustrate both lower bounds using a numerical example, test their performance, and present a real‐life case study from the area of railroad planning problems. © 2008 Wiley Periodicals, Inc. NETWORKS, 2009
Heat diffusion in layered media via the thin‐layer method
Authors: Joanni Andreas E. , Kausel Eduardo 
Published: December 2008

AbstractThe thin‐layer method is a semi‐analytical, numerical tool that has been successfully used in the past for wave motion in layered media, and differs from finite elements in that the medium is discretized only along a subset of the problem's dimensions, i.e. it combines partial discretization with analytical solutions. This paper shows that it can be applied just as well to heat diffusion, and results are given for impulsive as well as distributed point and dipole thermal sources with formulations in Cartesian and cylindrical coordinates. In essence, the method involves the discretization of the governing equations in the direction of layering together with analytical solutions for the remaining directions and for the variation in time. The solutions in response to spatially and temporally impulsive sources can also be used as fundamental solutions in the context of a boundary element formulation. This is illustrated herein by means of an example of a concrete slab overlain by two layers of carbon fiber reinforced polymers (CFRP), where a penny‐shaped crack is meant to simulate an area where the CFRP has debonded from the concrete. Copyright © 2008 John Wiley & Sons, Ltd.
Superconvergence of finite volume methods for the Stokes equations
Authors: Cui Ming , Ye Xiu 
Published: December 2008

AbstractA general superconvergence result of finite volume method for the Stokes equations is obtained by using a L2 projection post‐processing technique. This superconvergence result can be applied to different finite volume methods and to general quasi‐uniform meshes.© 2008 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 2009
The ill‐posed retrieval of aerosol extinction coefficient profiles (Poster Presentation)
Authors: Pornsawad P. , Böckmann C. , Ritter C. , Rafler M. 
Published: December 2008

AbstractWe present an improvement for the determination of aerosol extinction coefficient profiles from Raman lidar data in using regularization. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Preparation and properties investigation of PMMA/silica composites derived from silicic acid
Authors: Fu H. P. , Hong R. Y. , Zhang Y. J. , Li H. Z. , Xu B. , Zheng Y. , Wei D. G. 
Published: December 2008

AbstractHybrid materials based on silicic acid and polymethyl methacrylate (PMMA) were prepared by in situ bulk polymerization of a silicic acid sol and MMA mixture. Silicic acid sol was obtained by tetrahydrofuran (THF) extraction of silicic acid from water. Silicic acid was prepared by hydrolysis and condensation of sodium silicate in the presence of 3.6 M HCl. As a comparative study, PMMA composites filled by silica particles, which were derived from calcining the silicic acid gel, were prepared by a comparable in situ polymerization. Each set of PMMA/silica composites was subjected to thermal and mechanical studies. Residual THF in PMMA/silicic acid composites impacted the properties of the polymer composites. With increase in silica content, the PMMA composites filled with silica particles showed improved thermal and mechanical properties, whereas a decrease in thermal stability and mechanical strength was found for PMMA composites filled with silicic acid dissolved in THF. With a better compatibility with polymer matrix, silicic acid sol shows better reinforcement than silica particles in PMMA films prepared via blending of the corresponding THF solutions. Copyright © 2008 John Wiley & Sons, Ltd.