bluuebunny/crossref_metadata_2025 huggingface dataset:
Aerothermal Study of the Unsteady Flow Field in a Transonic Gas Turbine With Inlet Temperature Distortions
Authors: Salvadori S. , Montomoli F. , Martelli F. , Adami P. , Chana K. S. , Castillon L.
Published: March 2011

Computational fluid dynamics (CFD) prediction of the unsteady aerothermal interaction in the HP turbine stage, with inlet temperature nonuniformity, requires appropriate unsteady modeling and a low diffusive numerical scheme coupled with suitable turbulence models. This maybe referred to as high fidelity CFD. A numerical study has been conducted by the University of Florence in collaboration with ONERA to compare capabilities and limitations of their CFD codes for such flows. The test vehicle used for the investigation is a turbine stage of three-dimensional design from the QinetiQ turbine facility known as MT1. This stage is a high pressure transonic stage that has an unshrouded rotor, configured, and uncooled with 32 stators and 60 rotor blades. Two different CFD solvers are compared that use different unsteady treatments of the interaction. A reduced count ratio technique has been used by the University of Florence with its code HYBFLOW, while a phase lag model has been used by ONERA in their code, ELSA. Four different inlet conditions have been simulated and compared with focus on the experimental values provided by QinetiQ in the frame of TATEF and TATEF2 EU Sixth Framework Projects. The differences in terms of performance parameters and hot fluid redistribution, as well as the time- and pitch-averaged radial distributions on a plane downstream of the rotor blade, have been underlined. Special attention was given to the predictions of rotor blade unsteady pressure and heat transfer rates.
Tools and Techniques for Mobile Sensor Network Control
Authors: Hedrick J. Karl , Basso Brandon , Love Joshua , Lavis Benjamin M.
Published: March 2011

This paper compares some of the common tools and techniques that enable state-of-the-art systems to provide high-level control of mobile sensor networks. There is currently a great deal of interest in employing unmanned and autonomous vehicles in intelligence, surveillance, and reconnaissance operations. Although this paper addresses issues common to all mobile sensor networks, the applications presented are typically associated with autonomous vehicles. We focus specifically on three high-level areas: 1. mission definition languages that allow human users to compose missions defined in terms of tasks, 2. communication-addressing degradation and loss and relationship to underlying system architecture design, and 3. task allocation among the assets.
On a Numerical Method for Simultaneous Prediction of Stability and Surface Location Error in Low Radial Immersion Milling
Authors: Ding Ye , Zhu LiMin , Zhang XiaoJian , Ding Han
Published: March 2011

This brief proposes a numerical approach for simultaneous prediction of stability lobe diagrams and surface location error in low radial immersion milling based on the direct integration scheme and the precise time-integration method. First, the mathematical model of the milling dynamics considering the regenerative effect is presented in a state space form. With the cutter tooth passing period being divided equally into a finite number of elements, the response of the system is formulated on the basis of the direct integration scheme. Then, the four involved time-variant items, i.e., the time-periodic coefficient item, system state item, time delay item, and static force item in the integration terms of the response, are discretized via linear approximations, respectively. The corresponding matrix exponential related functions are all calculated by using the precise time-integration method. After the state transition expression on one small time interval being constructed, an explicit form for the discrete dynamic map of the system on one tooth passing period is established. Thereafter, the milling stability is predicted via Floquet theory and the surface location error is calculated from the fixed point of the dynamic map. The proposed method is verified by the benchmark theoretical and experimental results in published literature. The high efficiency of the algorithm is also demonstrated.
Rapid fabrication of bilayer graphene devices using direct laser writing photolithography
Authors: Leon J. A. , Alves E. S. , Elias D. C. , Brant J. C. , Barbosa T. C. , Malard L. M. , Pimenta M. A. , Ribeiro G. M. , Plentz F.
Published: March 2011

In this work the authors establish the use of the photolithography technique by direct laser writing for fabrication of devices on bilayer graphene coated with a photoresist. This technique is simple to use, versatile, reliable, and capable of achieving good throughput. The alignment of the patterns with the graphene flakes and between different lithography steps can be performed with an accuracy of about 0.5 μm allowing the placement of electric contacts and the definition of the Hall-bar geometries in an effective way. The devices fabricated were characterized by four-terminal resistance measurements as a function of the back gate and the Hall effect. The devices show initially p-type doping, but after annealing inside the cryostat at 127 °C in a He atmosphere, the samples become n-type. Different temperature dependence resistivity behaviors are found in bilayer graphene samples with high and low carrier densities. This approach offers a high degree of flexibility for fabrication of graphene devices.
ATP Inhibits the Generation and Function of Regulatory T Cells Through the Activation of Purinergic P2X Receptors
Authors: Schenk Ursula , Frascoli Michela , Proietti Michele , Geffers Robert , Traggiai Elisabetta , Buer Jan , Ricordi Camillo , Westendorf Astrid M. , Grassi Fabio
Published: March 2011

Purinergic signaling during inflammation converts immunosuppressive CD4
+
T cells into proinflammatory ones.
Terms of Disengagement
Authors: Gough Nancy R.
Published: March 2011

To prevent destruction of self, inhibitory receptors block clustering of activating receptors and cause natural killer cells to disengage.
T
regs
Promote Metastasis
Authors: Foley John F.
Published: March 2011

Receptor activator of nuclear factor κB ligand (RANKL) produced by regulatory T cells triggers the metastasis of breast cancer cells.
Touch Off a Fight
Authors: VanHook Annalisa M.
Published: March 2011

A contact pheromone produced by females induces aggression in male squid.
Sphingolipids and Retinal Degeneration
Authors: Gough Nancy R.
Published: March 2011

Too much dihydrosphingosine 1-phosphate enhances degradation of photoreceptor membrane proteins and leads to retinal degeneration in flies.
Reaching a Quorum Isn’t Simple
Authors: VanHook Annalisa M.
Published: March 2011

AphA and LuxR are opposing forces in the
Vibrio
quorum sensing pathway.
Colonization-Induced Host-Gut Microbial Metabolic Interaction
Authors: Claus Sandrine P. , Ellero Sandrine L. , Berger Bernard , Krause Lutz , Bruttin Anne , Molina Jérôme , Paris Alain , Want Elizabeth J. , de Waziers Isabelle , Cloarec Olivier , Richards Selena E. , Wang Yulan , Dumas Marc-Emmanuel , Ross Alastair , Rezzi Serge , Kochhar Sunil , Van Bladeren Peter , Lindon John C. , Holmes Elaine , Nicholson Jeremy K.
Published: March 2011

The gut microbiota enhances the host’s metabolic capacity for processing nutrients and drugs and modulate the activities of multiple pathways in a variety of organ systems. We have probed the systemic metabolic adaptation to gut colonization for 20 days following exposure of axenic mice (
n
= 35) to a typical environmental microbial background using high-resolution
1
H nuclear magnetic resonance (NMR) spectroscopy to analyze urine, plasma, liver, kidney, and colon (5 time points) metabolic profiles. Acquisition of the gut microbiota was associated with rapid increase in body weight (4%) over the first 5 days of colonization with parallel changes in multiple pathways in all compartments analyzed. The colonization process stimulated glycogenesis in the liver prior to triggering increases in hepatic triglyceride synthesis. These changes were associated with modifications of hepatic Cyp8b1 expression and the subsequent alteration of bile acid metabolites, including taurocholate and tauromuricholate, which are essential regulators of lipid absorption. Expression and activity of major drug-metabolizing enzymes (Cyp3a11 and Cyp2c29) were also significantly stimulated. Remarkably, statistical modeling of the interactions between hepatic metabolic profiles and microbial composition analyzed by 16S rRNA gene pyrosequencing revealed strong associations of the
Coriobacteriaceae
family with both the hepatic triglyceride, glucose, and glycogen levels and the metabolism of xenobiotics. These data demonstrate the importance of microbial activity in metabolic phenotype development, indicating that microbiota manipulation is a useful tool for beneficially modulating xenobiotic metabolism and pharmacokinetics in personalized health care.

IMPORTANCE
Gut bacteria have been associated with various essential biological functions in humans such as energy harvest and regulation of blood pressure. Furthermore, gut microbial colonization occurs after birth in parallel with other critical processes such as immune and cognitive development. Thus, it is essential to understand the bidirectional interaction between the host metabolism and its symbionts. Here, we describe the first evidence of an
in vivo
association between a family of bacteria and hepatic lipid metabolism. These results provide new insights into the fundamental mechanisms that regulate host-gut microbiota interactions and are thus of wide interest to microbiological, nutrition, metabolic, systems biology, and pharmaceutical research communities. This work will also contribute to developing novel strategies in the alteration of host-gut microbiota relationships which can in turn beneficially modulate the host metabolism.
Synthesis, structure and properties of a heterometallic 4f-5d complex [Sm(Hinic)3(H2O)2]n·(1.5nHgCl4)·(2nH2O)
Authors: Chen Wentong
Published: March 2011

A novel complex with samarium and mercury [Sm(Hinic)3(H2O)2]n·(1.5nHgCl4)·(2nH2O) (1) (Hinic = pyridine-4-carboxylic acid, i.e. isonicotinic acid), has been synthesized via hydrothermal reaction and structurally characterized. Complex 1 is characteristic of a one-dimensional polycationic chain-like structure. Photoluminescent investigation reveals that the title complex displays interesting emissions in violet, blue, green, orange and red regions. The luminescence spectra show the stronger violet and blue emissions than the green, orange and red ones. The green, orange and red emission bands are attributed to the characteristic emissions of 4G5/2→6HJ (J = 5/2, 7/2, 9/2) of Sm3+ ions. Optical absorption spectra of 1 reveal the presence of a wide optical bandgap of 3.27 eV. The magnetic properties show that complex 1 exhibits antiferromagnetic-like interactions.
Clinical predictors of delayed cerebral ischemia after subarachnoid hemorrhage: first experience with coil embolization in the management of ruptured cerebral aneurysms
Authors: Kawabata Yasuhiro , Horikawa Fumihiko , Ueno Yasushi , Sawada Masahiro , Isaka Fumiaki , Miyake Hidenori
Published: March 2011

Objective

The purpose of this study was to clarify the clinical predictors of delayed cerebral ischemia (DCI) after subarachnoid hemorrhage (SAH).

Methods

102 patients with ruptured cerebral aneurysms were treated (77 by clipping and 25 by coiling). 40 patients were male and 62 were female. Median age was 59 years (range 31–88). The modified Rankin Scale was used to assess functional outcomes 3 months after treatment or at discharge. The associations between potential clinical risk factors and DCI after SAH were assessed using the χ2test.

Results

52 patients (51.0%) had a good outcome and 13 patients (12.7%) died despite treatment. DCI was observed in 26 patients and hydrocephalus was observed in 37 patients. There were marginal differences in clinical outcomes between the treatment groups (p=0.053), mainly because functional outcomes were significantly superior in the coiling group (p=0.04) in patients with severe SAH. DCI was seen less frequently in the coiling group than in the clipping group (4.0% vs 32.4%, p=0.001). The presence of hydrocephalus was significantly associated with the occurrence of DCI (p<0.001). Multivariate logistic regression analysis also showed that the treatment modality and the presence of hydrocephalus were independent risk factors for DCI.

Conclusion

DCI was less frequently observed in the coiling group, and clinical outcomes were also superior in the coiling group, especially for patients with severe SAH. The results showed a significant correlation between DCI and hydrocephalus.
The role of circle of Willis anomalies in cerebral aneurysm rupture
Authors: Lazzaro Marc A , Ouyang Bichun , Chen Michael
Published: March 2011

Background and purpose

Limited data exist to guide patient selection for preventive treatment of unruptured cerebral aneurysms. Cerebral aneurysms have been associated with circle of Willis anomalies but whether this association is also related to aneurysm rupture is not known. The occurrence of cerebral aneurysm rupture when a circle of Willis anomaly was present or absent was compared.

Methods

Patients admitted over a 2 year period with a diagnosis of a cerebral aneurysm and an anterior communicating artery (ACoA) or posterior communicating artery (PCoA) aneurysm were included in the analysis. Brain vascular imaging was reviewed for aneurysm size, morphology and presence of circle of Willis anomaly. Relevant medical history and demographics were obtained from the medical records.

Results

Of the 113 patients with ACoA or PCoA aneurysms, 85 (75.2%) cases were ruptured. There were 49 (43.4%) PCoA aneurysms and 64 (56.6%) ACoA aneurysms. Mean aneurysm size was 5.65 mm (SD 3.31). A circle of Willis anomaly was identified in 46 (40.7%) of all patients. Circle of Willis anomalies were present in 38 (46.9%) ruptured aneurysm cases and eight (29.6%) unruptured aneurysm cases. Multivariate analysis revealed a higher risk of aneurysm rupture when a circle of Willis anomaly was present (p=0.0245, OR 3.72 (CI 1.18 to 11.66)).

Conclusions

This series shows that circle of Willis anomalies are more commonly found in ruptured as opposed to unruptured cerebral aneurysms of the anterior and posterior communicating arteries. The presence of a circle of Willis anomaly may be an important characteristic for selecting patients for preventive aneurysm treatment.
Intravascular ultrasound of the transverse sinus in two patients with pseudotumor cerebri: technical note
Authors: Radvany Martin G , Gomez Juan , Gailloud Philippe
Published: March 2011

Background

The etiology of transverse sinus stenosis in patients with pseudotumor cerebri syndrome (PTCS) is unknown. The imaging findings of transverse sinus stenosis in two patients with PTCS using intravascular ultrasound (IVUS) before and after endovascular therapy with stent placement are reported.

Material and methods

Retrospective, two patient, technical note.

Results

In both cases IVUS demonstrated focal intraluminal filling defects within the transverse sinuses, resulting in a narrowing of the sinus. In the first case, IVUS demonstrated cannulation of a narrow channel within the transverse sinus that initially precluded advancement of the stent. In the second case, IVUS demonstrated a significant narrowing when the pressure gradient was borderline and the area of stenosis was not obvious at angiography.

Conclusion

Besides distinguishing a potential extrinsic compression phenomenon from an intrinsic abnormality as the cause of the transverse sinus stenosis, IVUS also shows great promise as a tool helping to plan the interventional procedure and achieve optimal stent positioning in patients with PTCS.
Genetically modified plants as fish feed ingredients
Authors: Sissener Nini Hedberg , Sanden Monica , Krogdahl Åshild , Bakke Anne-Marie , Johannessen Lene Elisabeth , Hemre Gro-Ingunn
Published: March 2011

Genetically modified (GM) plants were first grown commercially more than 20 years ago, but their use is still controversial in some parts of the world. Many GM plant varieties are produced in large quantities globally and are approved for use in fish feeds both in Norway and the European Union. European consumers, however, are skeptical to fish produced by means of GM feed ingredients. Concerns have been raised regarding the safety of GM plants, including potential toxicity and (or) allergenicity of the novel protein, potential unintended effects, and risk of horizontal gene transfer to other species. This review will present the current state of knowledge regarding GM plants as fish feed ingredients, focusing on fish performance and health as well as the fate of the GM DNA fragments in the fish, identifying limitations of the current work and areas where further research is needed.
Life history strategy and impacts of environmental variability on early life stages of two marine fishes in the North Sea: an individual-based modelling approach
Authors: Daewel Ute , Peck Myron A. , Schrum Corinna
Published: March 2011

We employed a suite of coupled models to estimate the influence of environmental variability in the North Sea on early life stages of sprat ( Sprattus sprattus ), a small pelagic clupeid, and Atlantic cod ( Gadus morhua ), a demersal gadoid. Environmentally driven changes in bottom-up processes were projected to impact the survival and growth of eggs and larvae of these marine fish species in markedly different ways. We utilized a spatially explicit, individual-based model (IBM) to estimate larval fish survival and a 3D ecosystem model (ECOSMO) to provide variable prey fields. The model was applied to each of 3 years (1990, 1992, 1996) specifically characterized by interannual differences in water temperature in late winter and spring. Our results indicated that an important mechanism connecting environmental factors to larval fish survival was the match–mismatch dynamics of first-feeding larvae and their prey, which was species-specific because of (i) differences in the timing and locations of spawning, (ii) the duration of endogenously feeding life stages, and (iii) prey thresholds required for larval survival. Differences in transport processes also played an important role for the potential survival of larvae of both species.
THE PLANKTON IN ST. ANDREW'S BAY.
Authors: Willey D.Sc., F. A.
Published: March 2011

not available
OBJECT TRACKING OF VIDEO SEQUENCES IN CURVELET DOMAIN
Authors: NGUYEN THANH BINH , KHARE ASHISH
Published: March 2011

In this paper, we have proposed and presented a method for object tracking in video that exploits new tight frame of curvelets. We constructed a method of tracking that provides a sparse expansion for typical images having smooth contours. We used curvelet coefficients to segment and tracking of object in the sequence of frames. Results obtained for tracking of moving objects in video clips demonstrated an improved performance over other recent related methods available in the literature.
A MULTI-HISTOGRAM CLUSTERING APPROACH TOWARD MARKOV RANDOM FIELD FOR FOREGROUND SEGMENTATION
Authors: YANG WENJIA , DOU LIHUA , ZHAN JUAN
Published: March 2011

This paper presents a Bayesian approach for foreground segmentation in monocular image sequences. To overcome the limitations of background modeling in dealing with pixel-wise processing, spatial coherence and temporal persistency are formulated with background model under a maximum a posteriori probability (MAP)–Markov random field statistical (MRF) framework. Fuzzy clustering factor was introduced into the prior energy of MRFs for the new implementation scheme, where contextual constraints can be adaptively adjusted in terms of feature cues. Experimental results for several image sequences are provided to demonstrate the effectiveness of the proposed approach.
AN ADAPTIVE THRESHOLDING-BASED COLOR REDUCTION ALGORITHM AND ITS APPLICATIONS
Authors: PERIASAMY P. S. , ATHINARAYANAN S. , DURAISWAMY K.
Published: March 2011

In this paper, we present a novel adaptive thresholding-based color reduction algorithm. The proposed algorithm supports creation of a common palette for multiple images and transparent alpha images. This method was extensively tested for a large set of images and the results are reported here. The applications of proposed algorithm like qualitative image description, digital broadcasting, and bandwidth reduction are discussed in detail. The quality metric values of the experimental results show that the proposed method produces excellent results and outperforms existing state-of-the-art color reduction methods.
SECURITY OF THE MEDICAL MEDIA USING A HYBRID AND MULTIPLE WATERMARK TECHNIQUE
Authors: KALLEL MOHAMED , BOUHLEL MOHAMED-SALIM , LAPAYRE JEAN-CHRISTOPHE
Published: March 2011

This paper proposes a new approach of multiple and hybrid watermarks using two linked fields of insertion. This approach associates two different series of marks: one is sturdy guaranteeing the supervision of diffused media through the network and testifying to the identity of the owner of the medical image; the other series of marks, which is frail, insuring the integrity, the trace, and the archives of the medical diagnoses. In fact, this approach allows us to be benefited from the advantages of different insertion spaces (spatial and frequency field) and kind of two different fields of watermark. In the spatial field, the diagnosis of the doctor (frail marks) is inserted guaranteeing its records and its trace. In the frequency, the sturdy mark is inserted allowing to ensure the automatic control of the media through the network and testifying to the proprietor of the medical image.
ON THE FIFTH-POWER MOMENT OF Δ(x)
Authors: ZHANG DEYU , ZHAI WENGUANG
Published: March 2011

Let Δ(x) denote the error term in the Dirichlet divisor problem. In this paper, we study the fifth-power moment of Δ(x) and prove that [Formula: see text] with δ5 = 3/80, which improves the previous results.
THE MULTIPLICATIVE ORDERS OF CERTAIN GAUSS FACTORIALS
Authors: COSGRAVE JOHN B. , DILCHER KARL
Published: March 2011

A theorem of Gauss extending Wilson's theorem states the congruence (n - 1)n! ≡ -1 (mod n) whenever n has a primitive root, and ≡ 1 (mod n) otherwise, where Nn! denotes the product of all integers up to N that are relatively prime to n. In the spirit of this theorem, we study the multiplicative orders of [Formula: see text] (mod n) for odd prime powers pα. We prove a general result about the connection between the order for pα and for pα+1 and study exceptions to the general rule. Particular emphasis is given to the cases M = 3, M = 4 and M = 6, while the case M = 2 is already known.
SYMMETRY OF k-MARKED DURFEE SYMBOLS
Authors: BOULET CILANNE , KURŞUNGÖZ KAĞAN
Published: March 2011

Andrews introduced the k-marked Durfee symbols in his work defining a variant of the Atkin–Garvan moments of ranks. He provided and proved many identities and congruences using analytical methods. Here, we give an equivalent description of k-marked Durfee symbols, and using it we give combinatorial proofs to two results of Andrews'.
COMBINATORIAL PROOF OF ONE CONGRUENCE FOR THE BROKEN 1-DIAMOND PARTITION AND A GENERALIZATION
Authors: FU SHISHUO
Published: March 2011

In one of their recent collaborative papers, Andrews and Paule continue their study of partition functions via MacMahon's Partition Analysis by considering partition functions associated with directed graphs which consist of chains of diamond shape. They prove a congruence related to one of these partition functions and conjecture a number of similar congruence results. In this note, we reprove this congruence by constructing an explicit way to group partitions. Then we keep the essence of the method and manage to apply it to a different kind of plane partitions to get more general results and several other congruences.
VIBRATION CONTROL OF DIFFERENT FRP CABLES IN LONG-SPAN CABLE-STAYED BRIDGE UNDER INDIRECT EXCITATIONS
Authors: WANG XIN , WU ZHISHEN
Published: March 2011

To identify the vibration characteristics and potential vibration control of different fiber reinforced polymer (FRP) cables for long-span cable-stayed bridges, the critical resonant responses of these cables under indirect excitations including external and parametric excitations are studied in this paper. Based on theoretical equations, the primary resonant responses of different cables under indirect excitations were first calculated and compared, afterwards the influence of cable length and design stress to the resonant responses and the importance of external and parametric excitations were further studied. Analysis of results show that all of the FRP cables measuring 575 m in length possess lower resonant responses compared with steel cables, while the hybrid FRP cable with smart dampers exhibits even lower responses than the other FRP cables. Moreover, the external excitation induced resonance will become critical for some kinds of FRP cables with increasing cable length. A method on adjusting design stresses mitigates this critical resonance and benefits vibration control of FRP cables. In addition, parametric excitation plays a more important role in resonant responses for short-length cables in comparison to external excitation, whereas both parametric and external excitations are critically important for long-length cables.
A SEISMIC PERFORMANCE EVALUATION METHOD FOR STEEL STRUCTURES AGAINST LOCAL BUCKLING AND EXTRA-LOW CYCLE FATIGUE
Authors: GE HANBIN , LUO XIAOQUN
Published: March 2011

A practical performance evaluation method against local buckling and extra-low cycle fatigue (ELCF) is proposed in this study for steel structures. For thin-walled steel structures, local buckling is the main failure mode while brittle fracture due to ductile crack initiation under ELCF loading should be the dominant failure in thick-walled steel structures. A damage index verification method based on an FEM analysis using shell elements was previously presented by the authors to evaluate such a ductile failure. In the present study, a simplified verification method based on a fiber model FEM analysis using beam elements is proposed and the damage index is modified to consider strain concentration effects. Comparisons between experimental and analytical results show good prediction of ductile crack initiation in the current study. Finally, a unified verification method against local buckling and ELCF is summarized.
MAGNETOELECTRIC RESPONSES IN MULTIFERROIC COMPOSITE THIN FILMS
Authors: HU JIA-MIAN , MA JING , WANG JING , LI ZHENG , LIN YUAN-HUA , NAN C. W.
Published: March 2011

Multiferroic composite thin films of ferroelectrics and magnets have attracted ever-increasing interest in most recent years. In this review, magnetoelectric (ME) responses as well as their underlying ME coupling mechanisms in such multiferroic composite thin films are discussed, oriented by their potential applications in novel ME devices. Among them, the direct ME response, i.e., magnetic-field control of polarization, can be exploited for micro-sensor applications (sensing magnetic field, electric current, light, etc.), mainly determined by a strain-mediated coupling interaction. The converse ME response, i.e., electric-field modulation of magnetism, offers great opportunities for new potential devices for spintronics and in data storage applications. A series of prototype ME devices based on both direct and converse ME responses have been presented. The review concludes with a remark on the future possibilities and scientific challenges in this field.
PROGRESSES AND FURTHER CONSIDERATIONS ON THE RESEARCH OF PEROVSKITE LEAD-FREE PIEZOELECTRIC CERAMICS
Authors: XIAO DINGQUAN
Published: March 2011

The research on lead-free piezoelectric ceramics has been one of the important fields worldwide for years for the sustainable development of the world. In recent years, the author and his group concentrated their work on perovskite lead-free piezoelectric ceramics, especially on ( Bi 1/2 Na 1/2) TiO 3 ( BNT )- and K 1/2 Na 1/2 NbO 3 ( KNN )-based ceramics. In this paper, the researches of the composition design on BNT- and KNN-based lead-free piezoelectric ceramics, the effects of doping on the properties of these ceramics, the study of the temperature stability of these ceramics, and the fabrication technique used in the author's group for these ceramics are reviewed, and the further considerations and some prospects to be resolved in coming years from the viewpoint of the device applications of these ceramics are suggested.
FERROELECTRIC PROPERTIES OF (Bi0.5Na0.5)TiO3-BASED THIN FILM PREPARED BY PULSED LASER DEPOSITION
Authors: HEJAZI M. M. , SAFARI A.
Published: March 2011

We have developed a uniform and dense epitaxial thin film of 0.94( Bi 0.5 Na 0.5) TiO 3 - 0.004 × ( Bi 0.5 K 0.5) TiO 3 - 0.02 BaTiO 3 on a SrRuO 3 coated SrTiO 3 substrate by pulsed laser deposition method. The remnant polarization, coercive field and dielectric constant of the film with thickness of 315 nm, were measured to be 16.6 μC ⋅ cm−2, 147.5 kV ⋅ cm-1 and 640 (at 1 kHz), respectively. The film exhibited a high breakdown voltage and low leakage current of 1.1 × 10-5 A ⋅ cm-2 at 310 kV ⋅ cm-1. This ( Bi 0.5 Na 0.5) TiO 3-based thin film with a target composition in the rhombohedral side of the morphotropic phase boundary can be considered a potential candidate for relatively high power applications.
ENHANCED PIEZOELECTRIC PROPERTIES IN (Bi0.5K0.5)TiO3–(Bi0.5Na0.5)TiO3 FERROELECTRIC SINGLE CRYSTALS
Authors: MORISHITA AKIFUMI , KITANAKA YUUKI , IZUMI MAKOTO , NOGUCHI YUJI , MIYAYAMA MASARU
Published: March 2011

Single crystals of x( Bi,K ) TiO 3 - (1 - x)( Bi,Na ) TiO 3 (0.11 ≤ x ≤ 0.47) were grown by a flux method and their polarization and piezoelectric properties were investigated along 〈100〉 cubic at 25°C. Rietveld analysis of powder X-ray diffraction data provides a tentative phase diagram in this system: rhombohedral R3c for x ≤ 0.22, pseudocubic for 0.22 < x < 0.3 and tetragonal P4mm for 0.3 ≤ x. Piezoelectric strain properties show that the crystals (x = 0.38) exhibited an extremely large piezoelectric strain constant of 637 pm/V.
NOVEL LEAD ZIRCONATE TITANATE COMPOSITE VIA FREEZING TECHNOLOGY FOR HIGH FREQUENCY TRANSDUCER APPLICATIONS
Authors: ZHU B. P. , ZHOU Q. F. , HU C. H. , SHUNG K. K. , GORZKOWSKI E. P. , PAN M. J.
Published: March 2011

Novel PZT-5A ceramic-polymer composite was prepared via freezing technology. This composite exhibited good dielectric and ferroelectric behaviors. At 1 kHz, the dielectric constant and the dielectric loss were 546 and 0.046, respectively, while the remnant polarization was 13.0 μC/cm2 at room temperature. The electromechanical coupling coefficient (kt) of PZT-5A composite was measured to be 0.54, which is similar to that of PZT piezoelectric ceramic. The piezoelectric coefficient (d33) of PZT-5A composite was determined to be ~250 pC/N. Using this composite, a 58 MHz single element transducer with the bandwidth of 70% at –6dB was built, and the insertion loss was tested to be –29dB around the central frequency.
DIELECTRIC AND FERROELECTRIC PROPERTIES OF (1 - x) Pb(Mg1/3Nb2/3)O3–xPbZrO3 CERAMICS WITH CATION ORDER
Authors: ZHAO XIAOHUI , TAN XIAOLI
Published: March 2011

Electrical properties and the B-site cation order were investigated in the (1 - x) Pb ( Mg 1/3 Nb 2/3) O 3 - x PbZrO 3(0 ≤ x ≤ 0.25) solid solution ceramics. It was found that long range 1:1 B-site cation order can be developed through slow cooling during sintering in the solid solution with compositions around x = 0.10. The observed long range cation order is in sharp contrast to previous studies where a disordered structure was invariably resulted in the (1 - x) Pb ( Mg 1/3 Nb 2/3) O 3–x PbZrO 3 solid solution. The ceramics with cation order display dielectric and ferroelectric properties similar to those disordered ceramics reported in literature. The dielectric properties were also compared in detail to our previous Pb ( Mg 1/3 Zr 2x/3 Nb 2(1 - x)/3) O 3 - x/3 ceramics where Zr 4+ is designed to substitute Nb 5+ only. The results were discussed on the basis of the relationships between cation order and electric dipole order.
THE CONTRIBUTION OF ELECTRICAL CONDUCTIVITY, DIELECTRIC PERMITTIVITY AND DOMAIN SWITCHING IN FERROELECTRIC HYSTERESIS LOOPS
Authors: YAN HAIXUE , INAM FAWAD , VIOLA GIUSEPPE , NING HUANPO , ZHANG HONGTAO , JIANG QINGHUI , ZENG TAO , GAO ZHIPENG , REECE MIKE J
Published: March 2011

Triangular voltage waveform was employed to distinguish the contributions of dielectric permittivity, electric conductivity and domain switching in current-electric field curves. At the same time, it is shown how those contributions can affect the shape of the electric displacement — electric field loops (D–E loops). The effects of frequency, temperature and microstructure (point defects, grain size and texture) on the ferroelectric properties of several ferroelectric compositions is reported, including: BaTiO3; lead zirconate titanate (PZT); lead-free Na0.5K0.5NbO3; perovskite-like layer structured A2B2O7with super high Curie point (Tc); Aurivillius phase ferroelectric Bi3.15Nd0.5Ti3O12; and multiferroic Bi0.89La0.05Tb0.06FeO3. This systematic study provides an instructive outline in the measurement of ferroelectric properties and the analysis and interpretation of experimental data.
Stochastic approximation algorithms for constrained optimization via simulation
Authors: Bhatnagar Shalabh , Hemachandra N. , Mishra Vivek Kumar
Published: March 2011

We develop four algorithms for simulation-based optimization under multiple inequality constraints. Both the cost and the constraint functions are considered to be long-run averages of certain state-dependent single-stage functions. We pose the problem in the simulation optimization framework by using the Lagrange multiplier method. Two of our algorithms estimate only the gradient of the Lagrangian, while the other two estimate both the gradient and the Hessian of it. In the process, we also develop various new estimators for the gradient and Hessian. All our algorithms use two simulations each. Two of these algorithms are based on the smoothed functional (SF) technique, while the other two are based on the simultaneous perturbation stochastic approximation (SPSA) method. We prove the convergence of our algorithms and show numerical experiments on a setting involving an open Jackson network. The Newton-based SF algorithm is seen to show the best overall performance.
A dynamic sort-based DDM matching algorithm for HLA applications
Authors: Pan Ke , Turner Stephen John , Cai Wentong , Li Zengxiang
Published: March 2011

Simulation is a low-cost and safe alternative to solve complex problems in various areas. To promote reuse and interoperability of simulation applications and link geographically dispersed simulation components, distributed simulation was introduced. The High-Level Architecture (HLA) is the IEEE standard for distributed simulation. To optimize communication efficiency between simulation components, HLA defines a Data Distribution Management (DDM) service group for filtering out unnecessary data exchange. It relies on the computation of overlap between update and subscription regions, which is called “matching”. There are many existing matching algorithms, among which a sort-based approach improves efficiency by sorting region bounds before the actual matching process, and is found to outperform other existing matching algorithms in many situations. However, the existing algorithm performs matching for all regions in one round and cannot dynamically deal with a selective region modification without processing all the regions once again. Realizing that in many spatial applications, only a small subset of all regions are actually modified in each time step, this article proposes a dynamic sort-based matching algorithm to deal with this efficiently. Theoretical analysis has been carried out for the proposed algorithm and experimental results show that the proposed algorithm has significantly better performance than major existing matching algorithms at dynamic matching.
Robust sensor placements at informative and communication-efficient locations
Authors: Krause Andreas , Guestrin Carlos , Gupta Anupam , Kleinberg Jon
Published: March 2011

When monitoring spatial phenomena with wireless sensor networks, selecting the best sensor placements is a fundamental task. Not only should the sensors be informative, but they should also be able to communicate efficiently. In this article, we present a data-driven approach that addresses the three central aspects of this problem: measuring the predictive quality of a set of sensor locations (regardless of whether sensors were ever placed at these locations), predicting the communication cost involved with these placements, and designing an algorithm with provable quality guarantees that optimizes the NP-hard trade-off. Specifically, we use data from a pilot deployment to build nonparametric probabilistic models called
Gaussian Processes
(GPs) both for the spatial phenomena of interest and for the spatial variability of link qualities, which allows us to estimate predictive power and communication cost of unsensed locations. Surprisingly, uncertainty in the representation of link qualities plays an important role in estimating communication costs. Using these models, we present a novel, polynomial-time, data-driven algorithm, PSPIEL, which selects Sensor Placements at Informative and communication-Efficient Locations. Our approach exploits two important properties of this problem:
submodularity
, formalizing the intuition that adding a node to a small deployment can help more than adding a node to a large deployment; and
locality
, under which nodes that are far from each other provide
almost
independent information. Exploiting these properties, we prove strong approximation guarantees for our PSPIEL approach. In addition, we show how our placements can be made robust against changes in the environment, and how PSPIEL can be used to plan informative paths for information gathering using mobile robots. We also provide extensive experimental validation of this practical approach on several real-world placement problems, and built a complete system implementation on 46 Tmote Sky motes, demonstrating significant advantages over existing methods.
Energy-efficient congestion detection and avoidance in sensor networks
Authors: Wan Chieh-Yih , Eisenman Shane B. , Campbell Andrew T.
Published: March 2011

Event-driven sensor networks operate under an idle or light load and then suddenly become active in response to a detected or monitored event. The transport of event impulses is likely to lead to varying degrees of congestion in the network depending on the distribution and rate of packet sources in the network. It is during these periods of event impulses that the likelihood of congestion is greatest and the information in transit of most importance to users. To address this challenge we propose an energy-efficient congestion control scheme for sensor networks called
CODA (COngestion Detection and Avoidance)
that comprises three mechanisms: (i) receiver-based congestion detection; (ii) open-loop hop-by-hop backpressure; and (iii) closed-loop multisource regulation. We present the detailed design, implementation, and evaluation of CODA using simulation and experimentation. We define three important performance metrics (i.e., energy tax, fidelity penalty, and power) to evaluate the impact of CODA on the performance of sensing applications. We discuss the performance benefits and practical engineering challenges of implementing CODA in an experimental sensor network testbed based on Berkeley motes using CSMA. Simulation results indicate that CODA significantly improves the performance of data dissemination applications such as directed diffusion by mitigating hotspots, and reducing the energy tax and fidelity penalty on sensing applications. We also demonstrate that CODA is capable of responding to a number of congestion scenarios that we believe will be prevalent as the deployment of these networks accelerates.
Optimizing sensor movement planning for energy efficiency
Authors: Wang Guiling , Irwin Mary Jane , Fu Haoying , Berman Piotr , Zhang Wensheng , Porta Tom La
Published: March 2011

Conserving the energy for motion is an important yet not-well-addressed problem in mobile sensor networks. In this article, we study the problem of optimizing sensor movement for energy efficiency. We adopt a complete energy model to characterize the entire energy consumption in movement. Based on the model, we propose an optimal trapezoidal velocity schedule for minimizing energy consumption when the road condition is uniform; and a corresponding velocity schedule for the variable road condition by using continuous-state dynamic programming. Considering the variety in motion hardware, we also design one velocity schedule for simple microcontrollers, and one velocity schedule for relatively complex microcontrollers, respectively. Simulation results show that our velocity planning may have significant impact on energy conservation.
Critical sensor density for partial connectivity in large area wireless sensor networks
Authors: Cai Haiyan , Jia Xiaohua , Sha Mo
Published: March 2011

In this article, we study the critical sensor density for partial connectivity of a large area sensor network. We assume that sensor deployment follows the Poisson distribution. For a given partial connectivity requirement ρ, 0.5 < ρ < 1, we prove that there exists a critical sensor density λ
0
, around which the probability that at least a fraction ρ of sensors are connected in the network increases sharply from ε to 1-ε within a short interval of sensor density λ. The length of this interval is in the order of
O
(-log ε/log
A
) as
A
→ ∞, where
A
is the area of the sensor field, and the location of λ
0
is at the sensor density where the aforesaid probability is about 1/2. We prove the preceding theoretical results in the hexagonal model. We also extend our results to the disk model that models transmission range of sensors as disks. Simulations are performed to confirm the analytical results.
Using simulcast and scalable video coding to efficiently control channel switching delay in mobile tv broadcast networks
Authors: Hsu Cheng-Hsin , Hefeeda Mohamed
Published: March 2011

Many mobile TV standards dictate using energy saving schemes to increase the viewing time on mobile devices, since mobile receivers are battery powered. The most common scheme for saving energy is to make the base station broadcast the video data of a TV channel in bursts with a bit-rate much higher than the encoding rate of the video stream, which enables mobile devices to turn off their radio frequency circuits when not receiving bursts. Broadcasting TV channels in bursts, however, increases channel switching delay. The switching delay is important, because long and variable switching delays are annoying to users and may turn them away from the mobile TV service. In this article, we first analyze the burst broadcasting scheme currently used in many deployed mobile TV networks, and we show that it is not efficient in terms of controlling the channel switching delay. We then propose new schemes to guarantee that a given maximum switching delay is not exceeded
and
that the energy consumption of mobile devices is minimized. We prove the correctness of the proposed schemes and analytically analyze the achieved energy saving. We also use scalable video coding to generalize the proposed schemes in order to support mobile devices with heterogeneous resources. We implement the proposed schemes in a mobile TV testbed to show their practicality and to validate our theoretical analysis. The experimental results show that the proposed schemes: (i) significantly increase the energy saving achieved on mobile devices: up to 95% saving is observed, and (ii) support both homogeneous and heterogeneous mobile devices.
Adsorption Microcalorimetry: Recent Advances in Instrumentation and Application
Authors: Crowe Matthew C. , Campbell Charles T.
Published: March 2011

Adsorption microcalorimetry measures the energetics of adsorbate-surface interactions and can be performed by use of several different techniques. This review focuses on three methods: single-crystal adsorption calorimetry (SCAC), isothermal titration calorimetry (ITC), and electrochemical adsorption calorimetry. SCAC is a uniquely powerful technique that has been applied to a variety of atoms and molecules that represent a large variety of well-defined adsorbate species on a wide range of single-crystal surfaces. ITC and electrochemical microcalorimetry are useful for studying adsorption energies in liquid solutions (on surfaces of suspended powders) and at the electrode-electrolyte interface, respectively. Knowledge of the energetics of adsorbate formation is valuable to ongoing research in many fields, including catalysis, fuel cells, and solar power. In addition, calorimetric measurements serve as benchmarks for the improvement of computational approaches to understanding surface chemistry. We review instrumentation and applications, emphasizing our own work.
The Asphaltenes
Authors: Mullins Oliver C.
Published: March 2011

Asphaltenes, the most aromatic of the heaviest components of crude oil, are critical to all aspects of petroleum utilization, including reservoir characterization, production, transportation, refining, upgrading, paving, and coating materials. The asphaltenes, which are solid, have or impart crucial and often deleterious attributes in fluids such as high viscosity, emulsion stability, low distillate yields, and inopportune phase separation. Nevertheless, fundamental uncertainties had precluded a first-principles approach to asphaltenes until now. Recently, asphaltene science has undergone a renaissance; many basic molecular and nanocolloidal properties have been resolved and codified in the modified Yen model (also known as the Yen-Mullins model), thereby enabling predictive asphaltene science. Advances in analytical chemistry, especially mass spectrometry, enable the identification of tens of thousands of distinct chemical species in crude oils and asphaltenes. These and other powerful advances in asphaltene science fall under the banner of petroleomics, which incorporates predictive petroleum science and provides a framework for future developments.
Bioluminescence and Its Impact on Bioanalysis
Authors: Scott Daniel , Dikici Emre , Ensor Mark , Daunert Sylvia
Published: March 2011

There is an increasing need for versatile yet sensitive labels, posed by the demands for low detection in bioanalysis. Bioluminescent proteins have many desirable characteristics, including the ability to be detected at extremely low concentrations; no background interference from autofluorescent compounds present in samples; and compatibility with many miniaturized platforms, such as lab-on-a-chip and lab-on-a-CD systems. Bioluminescent proteins have found a plethora of analytical applications in intracellular monitoring, genetic regulation and detection, immuno- and binding assays, and whole-cell biosensors, among others. As new bioluminescent organisms are discovered and new bioluminescence proteins are characterized, use of these proteins will continue to dramatically improve our understanding of molecular and cellular events, as well as their applications for detection of environmental and biomedical samples.