bluuebunny/crossref_metadata_2025 huggingface dataset:
A PCM/heat pipe cooling system for reducing air conditioning in buildings: review of options and report on field tests
Authors: Etheridge D , Murphy K , Reay D
Published: February 2006

Air conditioning is now seen as a new and major contributor to CO2 emissions in the UK. This is partly due to global warming and partly to the increased use of IT systems. A novel system for reducing or eliminating the need for air conditioning was developed to the proof-of-concept stage under an earlier project at the University of Nottingham. The system makes use of heat pipes to transfer heat into and out of a phase change material which is ‘frozen’ during the night and ‘melted’ during the day. This paper describes a number of concepts for ‘free cooling’, and the background to the current concept, before detailing field tests on the system that have recently been completed and which demonstrate its effectiveness under real operating conditions. Systems were installed in two offices and detailed monitoring of their performance was carried out during the summer months. On the basis of the results obtained it is concluded that the system functions very well and is practically and technically the most attractive of the available alternatives to air conditioning. The fact that it is suited to retrofitting in existing buildings means that both the potential market and the CO2reductions are large. Practical application: The paper describes a novel system that is intended to provide passive cooling in naturally ventilated buildings. The novelty lies in the use of heat pipes and a fan to enhance the heat transfer to and from the phase change material (PCM) and the air. That this has been successful is shown by the ability of the system to exercise a degree of control over the room air temperature that is comparable to that of a conventional airconditioning system. The review provided in the paper may also be of use to other workers on PCMs and night cooling of naturally ventilated buildings.
Improvements in solar radiation models based on cloud data
Authors: Younes S , Muneer T
Published: February 2006

Simple radiation estimation models using meteorologically observed input parameters are often used in the applications requiring rough estimations of solar horizontal radiation. One of the parameters employed, cloud cover, is widely available from multiple regional and national weather stations. Kasten and Czeplak, Muneer and Gul, and Lam and Li, have proposed cloud-based models for the estimation of global and diffuse horizontal irradiance. In the current study, three new cloud-based models have been proposed. To compare the validity of the above models, statistical indicators have been developed for assessing the accuracy of estimation of global, diffuse and beam horizontal irradiance. The slope of the best fit line and the coefficient of determination between measured and calculated values, mean bias error, and root mean square error were calculated. In addition, the kurtosis and skewness of error histograms were also obtained. These parameters were used to obtain accuracy indicators for the models under validation. It was concluded that the proposed models outperformed the Kasten / Czeplak, and Lam / Li models, in both their original and modified forms. Practical application: Solar radiation data is an essential part of designing passive and active solar systems in building services. However, the solar radiation data is not always measured at the desired location, but other meteorological data are more available, therefore, tools have been developed to estimate the solar radiation from other measured parameters such as cloud cover. The models that are proposed are more accurate than their predecessors are, and provide global, beam and diffuse horizontal irradiance estimations. List of symbols
Experimental verification of a thermal radiation model for humanskin heat exposure
Authors: Wong LT , Hui PS
Published: February 2006

Skin pain and burns at an elevated skin layer temperature due to incident heat flux could be used to evaluate thermal hazards for some enclosed fire environments and mathematical expressions were proposed in literature for fire safety evaluations. In this work, a mathematical model for determining the skin layer temperature due to incident radiant heat flux is examined with experimental verification. Heat balance on the skin layer due to the heat flux and conductive heat transfer through it is considered. Specifically, the skin layer temperature at the head portion of an artificial thermal manikin was measured at certain incident radiant heat flux and compared with that calculated from the mathematical model. The results showed that the predictions were slightly higher than the measured values and the mathematical model would be useful in hazard assessment for some fire environments involving exposure of humans to a thermal radiation. Practical application: This paper presents the temperature measurement at a depth of 0.1 mm under the skin of an artificial thermal manikin’s head portion exposed to a vertical heated surface of 699 K in two orientations: facing and sideways to the surface. The result could be a useful source of information for the verification of any classical radiation model application to fire safety designs regarding heat exposure of the head portion of a person to heated surfaces.
Long term complete remission of severe nephrotic syndrome secondary to diffuse global (IV-G) lupus nephritis following autologous, haematopoietic peripheral stem (CD34+) cell transplantation
Authors: Marmont A M , Gualandi F , van Lint M T , Guastoni C , Bacigalupo A
Published: February 2006

Autologous haematopoietic stem cell transplantation has become an accepted powerful therapeutic procedure for patients with severe, intractable SLE. Here we describe a 26-year old patient with stage IV-G diffuse global proliferative lupus nephritis and refractory nephrotic syndrome who responded to autologous peripheral stem cell transplantation (ASCT) after two mobilization procedures. Five years later the patient is in complete clinical and immunologic remission. The indications for ASCT and its mechanism of action are briefly discussed.
Ocular manifestations of systemic lupus erythematosus: a clinical review
Authors: Peponis V , Kyttaris V C , Tyradellis C , Vergados I , Sitaras N M
Published: February 2006

Although the eye itself is regarded an ‘immune-privileged’ organ, systemic lupus erythematosus (SLE) can affect every ocular structure, leading, if left untreated, to significant visual loss or even blindness. Since ocular inflammation in SLE can antedate the diagnosis of the systemic disease and cause significant morbidity, prompt diagnosis and treatment of the underlying systemic autoimmune disease is imperative.
Sense of coherence and its impact on quality of life of patients with systemic lupus erythematosus
Authors: Abu-Shakra M , Keren A , Livshitz I , Delbar V , Bolotin A , Sukenik S , Kanat-Maymon Y
Published: February 2006

The sense of coherence (SOC) construct refers to a global orientation, which significantly determines the link between stressors, coping with disease and health. The aim of this work was to assess possible associations between SOC and quality of life (QOL) scores among women with SLE. Sixty consecutive SLE women and 88 healthy women were included in the study. QOL was assessed using the SF-36 and the WHO QOL-Bref scales. The SOC has three main sub-scales: comprehensibility, manageability and meaningfulness. Regression analyses were used to study associations between various parameters of SF-36, WHO QOL-Bref, SOC, SLEDAI, indices of end organ damage (SDI), and demographic variables. Mean SLEDAI and SDI scores were 4.5 (SD = 5.6) and 1.29 (SD = 2). SLE patients had significantly lower scores for all individual and summary sub-scales in the two QOL questionnaires compared with controls. SLE patients had significantly lower scores for the general, comprehensibility and meaningfulness sub-scales of SOC. No significant correlation was seen between SOC scores and measures of disease activity or end-organ damage. A strong linear correlation was seen between the scores of SOC, general WHO QOL-Bref, and the mental and physical component summary (MCS & PCS) scores of SF36. Age, SOC and SDI significantly affected the PCS score. SOC was the only variable independently associated with MCS. Education and SOC were significantly associated with the general WHO QOL-Bref. Age, education, SDI and SOC were independently associated with QOL of women with SLE.
Systemic lupus erythematosus in a multi-ethnic cohort (LUMINA): contributions of admixture and socioeconomic status to renal involvement
Authors: Alarcón G S , Bastian H M , Beasley T M , Roseman J M , Tan F K , Fessler B J , Vilá L M , McGwin G , Reveille J D ,   LUMINA Study Group
Published: February 2006

Renal involvement in systemic lupus erythematosus (SLE) is more frequent in minorities. We examined whether genetic or socioeconomic status (SES) explain these disparities in a large multiethnic (Hispanics from Texas and Puerto Rico, African Americans and Caucasians) SLE cohort. Renal involvement was defined as WHO Class II-V and/or proteinuria (>0.5 g/24 h or 3+) attributable to SLE and/or abnormal urinary sediment, proteinuria 2+, elevated serum creatinine/decreased creatinine clearance twice, 6 months apart present any time over the course of the disease. Ancestry informative markers (AIMS) were used to define the admixture proportions in each patient and group. Logistic regression models were examined to determine the percentage variance ( R2) in renal involvement related to ethnicity that is explained by socio-economic status (SES) and admixture (adjusting for age, gender and disease duration, basic model). Four-hundred and fifty-nine (out of 575) patients were included; renal involvement occurred in 44.6% Texas Hispanics, 11.3% Puerto Rico Hispanics, 45.8% African Americans, 18.3% Caucasians. SES accounted for 14.5% of the variance due to ethnicity (after adjusting for basic model variables), admixture 36.8% and both, 12.2%; 45.9% of the variance remained unexplained. Alternative models for decreased glomerula filtration rate and end-stage renal disease were comparable in the distribution of the explanatory variables. Our data indicate that genetic factors appear to be more important than SES in explaining the ethnic disparities in the occurrence of renal involvement.
Comparison of various statistical methods for identifying differential gene expression in replicated microarray data
Authors: Kim Seo Young , Lee Jae Won , Sohn In Suk
Published: February 2006

DNA microarray is a new tool in biotechnology, which allows the simultaneous monitoring of thousands of gene expression in cells. The goal of differential gene expression analysis is to identify those genes whose expression levels change significantly by the experimental conditions. Although various statistical methods have been suggested to confirm differential gene expression, only a few studies compared the performance of the statistical tests. In our study, we extensively compared three types of parametric methods such as T-test, B-statistic and Bayes T-test and three types of non-parametric methods such as samroc, significance analysis of microarray and a modified mixture model using both the simulated datasets and the three real microarray experiments.
Weighted confidence interval construction for binomial parameters
Authors: Olivier Jake , May Warren L.
Published: February 2006

Confidence intervals, in general, have become an important aspect of reporting statistical results. In particular, interval estimators for binomial proportions have been studied extensively in recent literature. The large-sample Wald intervals are known to perform poorly, but the Wilson intervals have been shown to perform well in a variety of situations. One criticism is the relative difficulty of computing the Wilson or quadratic intervals in comparison to the Wald intervals. We offer a computational formula for the Wilson intervals that is a weighted estimator of the observed proportion, p, and that based on an uninformative prior, 1/2. This contribution enhances our understanding of the coverage behavior of the Wilson intervals. In addition, we contrast the Wilson intervals with other well-known intervals for the case of zero successes.
Testing non-additivity (interaction) in two-way ANOVA tables with no replication
Authors: Alin Aylin , Kurt S
Published: February 2006

Testing for any significant interaction between two variables depends on the number of replicates in each cell of the two-way table and structure of the interaction. If there is interaction between two factors model of observations include interaction term and is called ‘non-additive model’ which makes interaction and non-additivity equivalent in terms of meaning. When there are several observations taken at each level combination of two variables, testing non-additivity can easily be done by usual two-way ANOVA method which cannot be used when there is only one observation per cell. For the cases with only one observation per cell, some methods have been developed starting with Tukey’s one-degree-of-freedom test in which interaction is supposed to be the product of two factor’s effects. There are other methods which are used for different structures of interaction when there is only one observation. In this paper, we review some of these tests. After presenting general methodology for the two-factor linear model with interaction effect and the general two-way ANOVA method when there are n > 1 observations per cell, we present some methods for testing non-additivity when there is only one observation per cell. Finally, we illustrate these methods on examples.
High Serum Levels of Growth Hormone (GH) and Insulin-Like Growth Factor-I (IGF-I) during High-Dose GH Treatment in Short Children Born Small for Gestational Age
Authors: van Dijk Marije , Mulder Paul , Houdijk Mieke , Mulder Jaap , Noordam Kees , Odink Roelof J. , Rongen-Westerlaken Ciska , Voorhoeve Paul , Waelkens Johan , Stokvis-Brantsma Jet , Hokken-Koelega Anita
Published: February 2006

Context: Epidemiological studies have indicated that high serum levels of GH and IGF-I are associated with long-term risks.

Objective: The objective of the study was to evaluate the changes in serum levels of GH during overnight profiles, IGF-I, and IGF binding protein 3 (IGFBP-3) in short small for gestational age (SGA) children during GH treatment with two doses.

Patients: Thirty-six prepubertal short SGA children were the subjects of this study.

Intervention: Subjects received 1 (group A) or 2 (group B) mg GH/m2·d.

Main Outcome Measures: At baseline and after 6 months of GH treatment, overnight GH profiles were performed, and serum IGF-I and IGFBP-3 levels were measured.

Results: After 6 months, group B had significantly higher GH levels during the profile (mean, maximum, and area under the curve above zero line) than group A (P < 0.009). In group B, maximum GH levels increased from 43.9–161 mU/liter (P < 0.0002), and in group A, from 57.2–104 mU/liter (P = 0.002). During the profile (i.e. 12 h per day), children of group B had mean GH levels of 64.4 vs. 34.8 mU/liter in group A (P = 0.001). The IGF-I and IGF-I to IGFBP-3 ratio sd scores increased significantly in both groups, but were higher in group B than A [1.5 vs. 0.2 (P = 0.002) and 1.4 vs. 0.3 (P = 0.007), respectively]. In group B, 74% of the children had IGF-I levels in the highest quintile during GH treatment compared with 19% in group A.

Conclusion: Our study shows that high-dose GH treatment in short SGA children results in high serum GH and IGF-I levels in most children. We recommend monitoring IGF-I levels during GH therapy to ensure that these remain within the normal range.
Increased Activation of Nuclear Factor κB Triggers Inflammation and Insulin Resistance in Polycystic Ovary Syndrome
Authors: González Frank , Rote Neal S. , Minium Judi , Kirwan John P.
Published: February 2006

Context: Insulin resistance and chronic low level inflammation are often present in women with polycystic ovary syndrome (PCOS).

Objective: The purpose of this study was to determine the effects of hyperglycemia on nuclear factor κB (NFκB) activation and inhibitory κB (IκB) from mononuclear cells (MNC) in PCOS.

Design and Setting: This was a prospective controlled study conducted at an academic medical center.

Patients: The study population consisted of 16 reproductive-age women with PCOS (eight lean, eight obese) and 16 age- and body composition-matched controls (eight lean, eight obese).

Main Outcome Measures: Insulin sensitivity (IS) was derived from a 2-h 75-g oral glucose tolerance test (ISOGTT). Intranuclear NFκB and IκB protein expression were quantitated from MNC obtained from blood drawn fasting and 2 h after glucose ingestion.

Results: ISOGTT was lower in PCOS compared with controls (3.3 ± 0.3 vs. 6.4 ± 0.9, P < 0.004). The percent change in intranuclear NFκB was higher in lean and obese PCOS compared with lean controls (42.5 ± 19.1 and 54.5 ± 12.5 vs. −14.1 ± 10.9, P < 0.006). The percent change in intranuclear NFκB correlated positively with 2-h post-glucose ingestion levels (r = 0.37; P < 0.04) and plasma testosterone (r = 0.49; P < 0.006) and correlated negatively with ISOGTT (r = 0.39; P < 0.04). The percent change in IκB was lower in lean and obese PCOS compared with lean controls (−22.3 ± 3.2 and −17.0 ± 5.0 vs. 8.4 ± 11.8, P < 0.02).

Conclusion: In response to hyperglycemia, intranuclear NFκB increases and IκB decreases in MNC of women with PCOS independent of obesity. This may represent a cardinal inflammatory signal that contributes to the induction of insulin resistance and hyperandrogenism in PCOS.
A Novel Thyroid Hormone Receptor-β Mutation That Fails to Bind Nuclear Receptor Corepressor in a Patient as an Apparent Cause of Severe, Predominantly Pituitary Resistance to Thyroid Hormone
Authors: Wu Sharon Y. , Cohen Ronald N. , Simsek Enver , Senses Dursun A. , Yar Nese E. , Grasberger Helmut , Noel Janet , Refetoff Samuel , Weiss Roy E.
Published: February 2006

Context: Resistance to thyroid hormone (RTH) is a dominantly inherited syndrome of variable tissue hyporesponsiveness to thyroid hormone (TH).

Objective: We report a newborn who presented with severe RTH (Mkar) with serum TSH 1500 mU/liter and free T3 greater than 50 pm (normal 3.1–9.4) and free T4 25.3 pm (normal 12–22). We hypothesized that the RTH was due to reduced ligand binding and/or abnormal interaction with nuclear cofactors.

Design: These were prospective in vivo and in vitro studies.

Setting: The study was conducted at a tertiary care university hospital.

Patients: Patients included a newborn child and two other subjects with RTH.

Intervention: The effect of various TH-lowering agents in the subject with RTH was studied. In vitro studies including EMSA and mammalian two-hybrid assay as well as in vitro transfection studies were conducted.

Main Outcome Measures: Sequencing of the TH receptor (TR)β and in vitro measurements of receptor-cofactor interaction were measured.

Results: Sequencing of the TRβ demonstrated a de novo heterozygous mutation, 1590_1591insT, resulting in a frameshift producing a mutant TRβ (mutTR)-β with a 28-amino acid (aa) nonsense sequence and 2-amino acid carboxyl-terminal extension. The Mkar mutation was evaluated in comparison to three other TRβ frameshift mutations in the carboxyl terminus. EMSA demonstrated that the Mkar mutTRβ1 had impaired ability to recruit nuclear receptor corepressor but intact association with silencing mediator of retinoid and thyroid receptor (SMRT).

Conclusion: Our data suggest that alterations in codons 436–453 in helix 11 result in significantly diminished association with nuclear receptor corepressor but not SMRT. This novel mutTRβ demonstrates nuclear corepressor specificity that results in severe predominantly pituitary RTH due to impaired release of SMRT.
Glycosylation catalyzed by lysyl hydroxylase 3 is essential for basement membranes
Authors: Ruotsalainen Heli , Sipilä Laura , Vapola Miia , Sormunen Raija , Salo Antti M. , Uitto Lahja , Mercer Derry K. , Robins Simon P. , Risteli Maija , Aszodi Attila , Fässler Reinhard , Myllylä Raili
Published: February 2006

Lysyl hydroxylase 3 (LH3) is a multifunctional enzyme possessing lysyl hydroxylase (LH), hydroxylysyl galactosyltransferase (GT) and galactosylhydroxylysyl glucosyltransferase (GGT) activities in vitro. To investigate the in vivo importance of LH3-catalyzed lysine hydroxylation and hydroxylysine-linked glycosylations, three different LH3-manipulated mouse lines were generated. Mice with a mutation that blocked only the LH activity of LH3 developed normally, but showed defects in the structure of the basement membrane and in collagen fibril organization in newborn skin and lung. Analysis of a hypomorphic LH3 mouse line with the same mutation, however, demonstrated that the reduction of the GGT activity of LH3 disrupts the localization of type IV collagen, and thus the formation of basement membranes during mouse embryogenesis leading to lethality at embryonic day (E) 9.5-14.5. Strikingly, survival of hypomorphic embryos and the formation of the basement membrane were directly correlated with the level of GGT activity. In addition, an LH3-knockout mouse lacked GGT activity leading to lethality at E9.5. The results confirm that LH3 has LH and GGT activities in vivo, LH3 is the main molecule responsible for GGT activity and that the GGT activity, not the LH activity of LH3, is essential for the formation of the basement membrane. Together our results demonstrate for the first time the importance of hydroxylysine-linked glycosylation for collagens.
Activity of the hSPCA1 Golgi Ca2+ pump is essential for Ca2+-mediated Ca2+ response and cell viability in Darier disease
Authors: Foggia Lucie , Aronchik Ida , Aberg Karin , Brown Barbara , Hovnanian Alain , Mauro Theodora M.
Published: February 2006

Keratinocyte differentiation, adhesion and motility are directed by extracellular Ca2+ concentration increases, which in turn increase intracellular Ca2+ levels. Normal keratinocytes, in contrast to most non-excitable cells, require Ca2+ release from both Golgi and endoplasmic reticulum Ca2+ stores for efficient Ca2+ signaling. Dysfunction of the Golgi human secretory pathway Ca2+-ATPase hSPCA1, encoded by ATP2C1, abrogates Ca2+ signaling and causes the acantholytic genodermatosis, Hailey-Hailey disease. We have examined the role of the endoplasmic reticulum Ca2+ store, established and maintained by the sarcoplasmic and endoplasmic reticulum Ca2+-ATPase SERCA2 encoded by ATP2A2, in Ca2+ signaling. Although previous studies have shown acute SERCA2 inactivation to abrogate Ca2+ signaling, we find that chronic inactivation of ATP2A2 in keratinocytes from patients with the similar acantholytic genodermatosis, Darier disease, does not impair the response to raised extracellular Ca2+ levels. This normal response is due to a compensatory upregulation of hSPCA1, as inactivating ATP2C1 expression with siRNA blocks the response to raised extracellular Ca2+ concentrations in both normal and Darier keratinocytes. ATP2C1 inactivation also diminishes Darier disease keratinocyte viability, suggesting that compensatory ATP2C1 upregulation maintains viability and partially compensates for defective endoplasmic reticulum Ca2+-ATPase in Darier disease keratinocytes. Keratinocytes thus are unique among mammalian cells in their ability to use the Golgi Ca2+ store to mediate Ca2+ signaling.
Regulation of membrane traffic by phosphoinositide 3-kinases
Authors: Lindmo Karine , Stenmark Harald
Published: February 2006

Phosphoinositide (PI) 3-kinases control essential cellular functions such as cytoskeletal dynamics, signal transduction and membrane trafficking. FYVE, PX and PH domains mediate the binding of effector proteins to the lipid products of PI 3-kinases. Recent studies have provided significant insights into the roles of PI 3-kinases, their catalytic products and their downstream effectors in membrane trafficking. Class I and II PI 3-kinases trigger receptor-induced trafficking processes, such as phagocytosis, macropinocytosis and regulated exocytosis. Class I PI 3-kinases also function to inhibit autophagy. By contrast, class III PI 3-kinases mainly mediate receptor-independent trafficking events, which mostly are related to endocytic membrane traffic, phagosome maturation and autophagy.
SEWHAPM: Development of a Water Hydraulic Axial Piston Motor for Underwater Tool Systems
Authors: Nie S. L. , Huang G. H. , Zhu Y. Q. , Li Z. Y. , Li Y. P.
Published: February 2006

Water hydraulic motor (WHM) is an important transmission component in a water hydraulic system. Because of different physicochemical properties of raw water when compared with mineral oil, the design for the WHM would be different from that for a mineral oil one. A static equilibrium-type water hydraulic axial piston motor (SEWHAPM), which is equipped with a global-moment-balanced plate valve and a hydrostatic slipper bearing with a concentric gap damper, is developed in this research. The mechanism of the global-moment-balanced plate valve is analysed to eliminate the irregular wear of the plate valve. Next, the relevant design guideline is constructed. A mathematical model of the hydrostatic slipper bearing is established, and the performance characteristics of the bearing are discussed. The theoretical analyses indicate that the load-carrying capacity of this hydrostatic slipper bearing is not correlated with system pressure, water viscosity, temperature, or rotor speed, and that the lubrication film thickness of the bearing possesses high rigidity. The fundamental principle for designing the hydrostatic slipper bearing is also derived. On the basis of a material-screening experiment, a SEWHAPM is fabricated and tested on a water hydraulic-component-performance test stand. The experimental results show that developed SEWHAPM is feasible, with its volumetric, mechanical, and total efficiencies being ∼86, 80, and 70 per cent, respectively, under a pressure of 10 MPa. The maximal output torque can reach ∼19.5Nm; the maximal speed can reach 3000 r/min. As a result of the aforementioned development, the SEWHAPM has been successfully used in an underwater tool system since 2002, and its performance has been tested, demonstrating that the developed equipment can meet the regulated requirements for its practical applications.
Understanding the Effect of Seams on the Aerodynamics of an Association Football
Authors: Carré M. J. , Goodwill S. R. , Haake S. J.
Published: February 2006

The aerodynamic properties of an association football were measured using a wind tunnel arrangement. A third scale model of a generic football (with seams) was used in addition to a ‘mini-football’. As the wind speed was increased, the drag coefficient decreased from 0.5 to 0.2, suggesting a transition from laminar to turbulent behaviour in the boundary layer. For spinning footballs, the Magnus effect was observed and it was found that reverse Magnus effects were possible at low Reynolds numbers. Measurements on spinning smooth spheres found that laminar behaviour led to a high drag coefficient for a large range of Reynolds numbers, and Magnus effects were inconsistent, but generally showed reverse Magnus behaviour at high Reynolds number and spin parameter. Trajectory simulations of free kicks demonstrated that a football that is struck in the centre will follow a near straight trajectory, dipping slightly before reaching the goal, whereas a football that is struck off centre will bend before reaching the goal, but will have a significantly longer flight time. The curving kick simulation was repeated for a smooth ball, which resulted in a longer flight time, due to increased drag, and the ball curving in the opposite direction, due to reverse Magnus effects. The presence of seams was found to encourage turbulent behaviour, resulting in reduced drag and more predictable Magnus behaviour for a conventional football, compared with a smooth ball.
Rotational Motion Control of a Washing Machine Using Electrorheological Clutches and Brakes
Authors: Choi S. B. , Lee D. Y.
Published: February 2006

In this work, a rotational motion control of a washing machine featuring an electrorheological (ER) clutch/brake actuators is investigated. After analysing the field-dependent transmission and braking torques of the actuator on the basis of Bingham model, two sets of ER clutch/brake actuators are manufactured. The dynamic model of the actuators is then formulated by considering time constants. Subsequently, the actuators are applied to a small-sized pulsator type washing machine for rotational motion control. The control system model represented by spin-basket and pulsator motions is established and PID controllers are designed for two motions. The controllers are experimentally realized for washing and dehydrating motions under various loads. In addition, durability test for the washing motion control has been undertaken to demonstrate practical feasibility.
C-Gears: Geometry and Machining
Authors: Arafa H. A.
Published: February 2006

Cylindrical gears with lengthwise curved teeth, or C-gears for short, have repeatedly been suggested during the past 90 years, without having found widespread application. However, it seems that they are presently on the verge of being reconsidered for applications where their characteristic tolerance of misalignment is indispensable, particularly when this merit outweighs all other issues of concern. In this paper, the geometrical features of 11 different forms in which C-gears could come are detailed in connection with their cutting and finish-grinding methods. The limitations and demerits are discussed and some problem areas that need further investigation are highlighted. The information given herein should be valuable to mechanical engineers whenever they would envisage using C-gears or designing generators for them. In spite of the sometimes lengthy description of the geometry, a scent of the history of C-gears and their machining methods is perceived throughout the paper.
Comparison of Contact Mechanics between a Total Hip Replacement and a Hip Resurfacing with a Metal-On-Metal Articulation
Authors: Liu F , Udofia I. J. , Jin Z. M. , Hirt F , Rieker C , Roberts P , Grigoris P
Published: February 2006

The finite element method was employed in this study to compare the contact mechanics at the bearing surfaces between a metal-on-metal hip resurfacing prosthesis and a total hip replacement with a similar bearing combination. The hip resurfacing prosthesis was implanted and modelled in a full three-dimensional pelvic and femoral bone. A significant reduction in the predicted contact pressure by over 53 per cent as well as a corresponding increase in the contact area by approximately 220 per cent was found in the hip resurfacing prosthesis, in comparison to the total hip replacement. The reduced contact pressure and increased contact area in the hip resurfacing system were due to the combination of the larger bearing size and increased elasticity from the metallic cup and the underlying bone support. The hip resurfacing prosthesis may therefore offer a significant improvement in the tribology at the metallic bearing surfaces, thus offering a potential advantage in terms of long-term clinical success over current total hip replacements with reported survivorships over 20 years.
KHV Indexing Cam Mechanism: A New Intermittent Mechanism
Authors: Wang Hao , Zhang Ce , Chen Guanlong
Published: February 2006

The KHV indexing cam mechanism is a new type intermittent mechanism that has a structure similar to the KHV planetary gear transmission (one type of the planetary drive with small teeth difference, where K indicates the sun gear, H indicates the pivoted arm, and V indicates the output mechanism). This paper focuses on the generation of a pitch curve and a cam profile in such a new mechanism. Three types of the KHV indexing cam mechanism are compared and discussed, and the equations of cam's pitch curves are derived. The cam's profile is generated by Boolean operations on the offsets of the cam's pitch curve. After this, the cusps on the cam profile are eliminated and replaced by a particular Hermite curve. The animations of all three types are illustrated, and a prototype of such mechanism is reported.
Probabilistic Failure Analysis of Austenitic Nuclear Pipelines against Stress Corrosion Cracking
Authors: Priya C , Rao K. B. , Anoop M. B. , Lakshmanan N , Gopika V , Kushwaha H. S. , Saraf R. K.
Published: February 2006

Stress corrosion cracking (SCC) is an important degradation mechanism to be considered for failure assessment of nuclear piping components made of austenitic steels. In this paper, an attempt has been made to compute the failure probabilities of a piping component against SCC with time using Monte Carlo simulation (MCS) technique. The initiation and propagation stages of stress corrosion cracks are modelled using the general methodology recommended in PRAISE modified by using the recommendations given by ASM for more rational modelling of stress field around cracks for estimating their growth with time. Degree of sensitization, applied stress, time to initiation of SCC, initial crack length, and initiation crack growth velocity are considered as random variables. An attempt has been made to study the stochastic propagation of stress corrosion cracks with time, using MCS technique. The trend of the distribution of crack depths at the initial stages obtained from simulation are compared and is found to be in satisfactory agreement with the relevant experimental observations reported in the literature. The failure probabilities are computed using two different failure criteria, namely (a) based on net-section stress and detectable leak rate as recommended in PRAISE and (b) based on R6 approach (using R6-option 1 curve as the failure assessment diagram). The procedure presented in the paper is general and the usefulness of the same is demonstrated through an example problem.
Process Planning for Multi-Directional Laser-Based Direct Metal Deposition
Authors: Dwivedi R , Kovacevic R
Published: February 2006

Laser-based direct metal deposition has demonstrated the capability to deposit metal along multiple directions. Suitable control of parameters, namely, the metal-powder feed rate, the traverse speed, and the laser power allow fabrication of a desired shape for a large family of parts. The capability to deposit material along multiple directions eliminates the requirement for support structures. However, accessing the point of deposition and manipulating the direction of deposition require a coordinated control of two kinematical systems; one is related to the deposition platform, whereas the other is related to the deposition head. The identification of the key challenges, a mathematical basis of the process, possible solutions, the subsequent process planning, and experimental results are the subjects of this article.
Sensitivity analysis of transient diesel engine simulation
Authors: Rakopoulos C D , Glakoumis E G
Published: February 2006

:An experimentally validated simulation code is used to study the errors induced by various, usually applied, modelling simplifications in the prediction of diesel engine operation under transient conditions after a ramp increase in load. The following simulation cases are investigated: multicylinder engine modelling, with the equations of each cylinder solved separately during each transient cycle; cylinder wall temperature modelling, with the analytical heat convection-conduction scheme compared with the usual constant wall temperature approach; in-cylinder radiation temperature correction to compensate for the underestimation of maximum temperatures from single-zone modelling; mathematical fuel pump modelling in contrast to steady state fuel injection curves; friction modelling during a transient event simulated using equations per degree crank angle as opposed to the ‘mean’ f.m.e.p. approach; and ‘deterioration’ scenarios applied to both friction and combustion rates to compensate for the peculiarities of transient operation. It is revealed that the multicylinder, analytical friction, and detailed fuel pump modelling can have an important effect on the prediction of diesel engine transient operation and thus should not be excluded from a complete transient model. The cylinder wall temperature simulation used only marginally affects the prediction of transients, whereas the friction and combustion deterioration can have quite dramatic results but need further experimental validation.
Global positioning system-based vehicle control for automated parking
Authors: Zhu C , Rajamani R
Published: February 2006

This paper addresses control system design for parking of an automated vehicle. The challenge in the control design task for parking arises from the fact that the vehicle constitutes an underactuated non-holonomic system. There are three generalized coordinates to be controlled but only two constrained control inputs. A control system designed to track a two-piece trajectory is developed with only some of the degrees of freedom being controlled in each piece of the trajectory. Constraints on the available parking space, the lateral distance available, and steering limits are taken into consideration in the trajectory design. The trajectory design and control system ensure that the vehicle can reach any desired final point with any desired final orientation.

A major portion of the paper concentrates on experimental implementation of the control system. The experimental demonstration is carried out on a truck using a differential global positioning system (GPS) to sense the position of the vehicle. Experimental results show that the truck is able to maintain a spacing accuracy better than 40 cm in tracking the desired trajectory while being driven backwards.
Deriving on-road spatial vehicle emission profiles from chassis dynamometer experiments
Authors: Samuel S , Morrey D , Garner C P , Taylor D H C , Fowkes M , Austin L
Published: February 2006

A method has been derived for the identification of spatial emission hot-spots on vehicle road routes using chassis dynamometer data. The work presented here uses tailpipe-out carbon monoxide (CO) levels to demonstrate the application of the method. The approach is used to analyse critically methods used by legislators that derive road-side emission levels from the vehicle emission inventory and legislative emission levels. The work presented in this paper demonstrates that the generic approach using vehicle speed, gear change patterns, spatial geographical data, and route geometric information is sufficient for the identification of the location of emission hot-spots in any journey route of interest.
Some aspects concerning the geometry of a hinged engine with a variable compression ratio
Authors: Clenci A , Descombes G , Podevin P , Hara V
Published: February 2006

An improvement in automotive fuel consumption has been for many years the most important challenge in engine development. In a century of automotive spark ignition engine development, only two parameters were subject to automatic control: the air-fuel ratio and spark advance. Ever since, a wide range of technologies has been developed in order to improve fuel economy further. The following strategy was used: the identification of the sources of losses in the conventional spark ignition engine and then the attempt to reduce them one by one. The potential of these technologies needs to be evaluated by a cost and consumption benefit trade-off and all these, of course, without affecting the power level. In this context, the authors are about to develop a variable geometrical compression ratio engine, in order to overcome the main drawback of the spark ignition engine: the continuous variation of the real rate of compression, caused by the load control.

The concept of the variable geometrical compression ratio (VCR) engine is the subject of a patent and consists of a hinged mechanism. It is an intrinsic, automatic self-regulation system with a fast response time and at the same time is a natural development of the classic engine. So far, two prototypes have been designed and tested.

The paper presents some specific features regarding hinge position choice. The following are taken into consideration: the upper block rotational angle, added angle of the piston, tipping torque, and relative motion of the camshaft with respect to the crankshaft.
Computational study of the effects of the throat diameter of the piston bowl for the performance and emissions of a high-speed direct-injection diesel engine
Authors: Zhu Y , Zhao H
Published: February 2006

The purpose of this study is to investigate computationally the effect of the bowl shape with different throat diameters associated with different re-entrant lips using an experimentally validated KIVA3V-based computational fluid dynamics (CFD) program.

In order to investigate individually the effects of the throat diameter and the re-entrant lip shape with the minimum interactive effects on other parameters, the bowl pip height and width were changed in order to maintain the same bowl height and volume. Three bowls, namely the baseline bowl, a bowl with increased throat diameter with limited pip height, and a bowl with increased throat diameter with the same pip height as the baseline, were investigated at the three speeds 4000 r/min maximum power, 2000 r/min maximum torque with three injector protrusions and three injection timings, and 1600 r/min part-load with two EGR fraction and injection timings respectively. It was found that the bowl with larger throat diameter and high pip has the best air-fuel mixing of all three bowls.
Validation of the small-punch test as a technique for characterizing the mechanical properties of acrylic bone cement
Authors: Dunne N J , Leonard D , Daly C , Buchanan F J , Orr J F
Published: February 2006

This paper examines the validity of using the small-punch test technique as a means of quantifying the mechanical properties of acrylic bone cement under different test conditions. The elastic moduli calculated using the small-punch test method were compared with data measured using the international standard for acrylic bone resin, ISO 5833. Conclusions from the study indicate that the small-punch test is a reproducible miniature specimen test method that can be used to characterize the mechanical properties of retrieved acrylic bone cement as used in total joint replacement surgery. Moreover, the test conditions were found to influence the elastic modulus of acrylic bone cement. The test temperature had a greater effect on the elastic behaviour of the bone cement than the test medium.
A simple fully integrated contact-coupled wear prediction for ultra-high molecular weight polyethylene hip implants
Authors: Kang L , Galvin A L , Jin Z M , Fisher J
Published: February 2006

A fully coupled contact and wear model was developed in the present study for hip implants employing an ultra-high molecular weight polyethylene (UHMWPE) cup in combination with a metallic or ceramic femoral head. A simple elasticity equation based on the concept of constrained column model was employed to solve the contact mechanics between the acetabular cup and the femoral head under the three-dimensional physiological loading condition. The wear model was based on the classical Archard—Lancaster equation in common with all other studies reported in the literature. The fully coupled contact and wear model was applied to both conventional and cross-linked UHMWPE cups under a wide range of design parameters such as the clearance and the femoral head radius. The predicted linear and volumetric wear as well as their rates for conventional UHMWPE cups were found to be in good agreement with those obtained from a similar analysis by Maxian but using the finite element method for the contact mechanics analysis. The predicted maximum contact pressure was found to decrease rapidly within the first 106 cycles, and below the limit to cause plastic deformation within the UHMWPE cup with a nominal radial clearance of 0.2 mm. The effect of the clearance between the head and the cup on the predicted wear was found to be negligible. For the cross-linked UHMWPE cup with relatively large diameters up to 48 mm and a fixed outside diameter of 50 mm, the predicted wear, which was found to increase with increasing femoral head radius, remained small owing to the small wear factor associated with these materials. Furthermore, if the head diameter increases beyond 42 mm, a rapid increase in the contact pressure was predicted, owing to the decrease in the wall thickness of the cross-linked UHMWPE cup.
Influence of hyaluronic acid on the time-dependent friction response of articular cartilage under different conditions
Authors: Bell C J , Ingham E , Fisher J
Published: February 2006

Therapeutic lubricant injections of hyaluronic acid are a relatively recent treatment for osteoarthritis. Their efficacy however, in vivo has been subject to much debate.

Frictional properties of cartilage-cartilage contacts under both static and dynamic loading conditions have been investigated, using healthy cartilage and cartilage with a physically disrupted surface, with and without the addition of a therapeutic lubricant, hyaluronic acid.

Most of the cartilage friction models produced typical time-dependent loading curves, with a rise in static friction with loading time. For the dynamic loading conditions the rise in friction with loading time was dependent on the spatial (and time) variation in the load on the cartilage plate. For sliding distances of 4 mm or greater, when the cartilage plate was unloaded during sliding, the dynamic friction remained low whereas, with shorter sliding distances, the dynamic friction increased with increasing loading time. Static friction was higher than dynamic friction (under the same tribological conditions). The ‘damaged’ cartilage models produced higher friction than healthy cartilage under equivalent tribological conditions.

It was shown that hyaluronic acid was an effective boundary lubricant for articular cartilage under static conditions with both healthy and damaged cartilage surfaces. Hyaluronic acid was less effective under dynamic conditions. However, these dynamic conditions had low friction values with the control lubricant because of the effectiveness of the intrinsic biphasic lubrication of the cartilage. It was only under the tribological conditions in which the cartilage friction was higher and rising with increasing loading time because of depletion of the intrinsic biphasic lubrication, that the role of hyaluronic acid as an effective therapeutic lubricant was demonstrated.
The biomechanics of abfraction
Authors: Rees J S
Published: February 2006

The role of occlusal loading in the development of non-carious cervical lesions is becoming increasingly prominent. It is suggested that high occlusal loads result in large stress concentrations in the cervical region of the teeth. These stresses may be high enough to cause disruption of the bonds between the hydroxyapatite crystals, eventually resulting in the loss of cervical enamel.

This article reviews the evidence to support the thesis that occlusal loading can contribute to the process of non-carious cervical tooth loss or abfraction. It also reviews the potential interactions between occlusal loading and erosion that may contribute to non-carious cervical tooth loss.