bluuebunny/crossref_metadata_2025 huggingface dataset:
Risk Planning and Mitigation in Oil Well Fields
Authors: Gaurina-Međimurec Nediljka , Pašić Borivoje , Mijić Petar
Published: February 2016

Lost circulation presents one of the major risks associated with drilling. The complete prevention of lost circulation is impossible but limiting circulation loss is possible if certain precautions are taken. Industry experience has proved that is often easier and more effective to prevent the occurrence of loss than to attempt to stop or reduce them once they have started. The problem of lost circulation was magnified considerably when operators began drilling deeper and/or depleted formations. A strategy for successful management of lost circulation should include preventative (best drilling practices, drilling fluid selection, and wellbore strengthening materials) and remedial measures when lost circulation occurs through the use of lost circulation materials. In this paper the authors present lost circulation zones and causes, potential zones of lost circulation, excessive downhole pressures causes, preventive measures, tools and methods for locating loss zones and determining the severity of loss, lost circulation materials, and recommended treatments.
Influence of Personality on Programming Styles an Empirical Study
Authors: Karimi Zahra , Baraani-Dastjerdi Ahmad , Ghasem-Aghaee Nasser , Wagner Stefan
Published: February 2016

Each programmer tend to his or her own style in programming and human factors may explain these differences in style which has considerable influence on tooling, processes and productivity. The objective of this paper is to study the influence of a previously un-investigated factor, personality, on programming styles. The authors did a survey study on 68 programmers in the University of Stuttgart. Programming experience, attitude towards programming, five personality factors, and programming styles were measured via self-assessed survey. The authors did statistical analysis to investigate links between human factors and programming styles. They found that programming experience is the most influential factor in programming styles but personality is more evident in different programming styles. They conclude that programming styles are a matter of personal preferences and help reveal the influence of personality in programming. Further research is needed to explore new programming styles, measure them and investigate the influence of personality on them.
Simulation and Study on the Formation Mechanism of Chip Based on Micro Cutting
Authors: Li Qi Ding , Li Ke Tian , Li Hai Min
Published: February 2016

A finite element model based on Abaqus/Explicit is built. Micro cutting mechanism of Al7075 with different cutting depth is simulated and analyzed. The simulation results show that if the cutting depth is more than 10μm, the chip is a kind of continuous curl. If the cutting depth is less than 10μm, the chip is a kind of feathery squeeze debris. When the cutting depth is very small (3μm), the shape of chips is just like discontinuous wrinkle. By contrasting the simulation results of cutting force with its theoretical values, they have the same result. The model of the chip prediction could achieve ideal simulation results.
3D Simulation of the Ultra-Precision V-Groove Machine Tool
Authors: Huang Hui Jing , Gao Wei Qiang , Liu Jian Qun
Published: February 2016

This paper develops a three dimensional (3D) simulation system with QT platform and OpenGL 3D library by adopting the driver and Aerotech’s linear motor as hardware platform and INtime and A3200 controller as the software platform. The system uses numerical control (NC) code syntax checking module to test the NC code syntax and applies 3D simulation module to display the actual machining process. The interference and collision detection module is built in this system to detect the problem during the actual processing. The system therefore contributes to avoiding the trial and tests for the ultra-precision machining process and improving the machining efficiency as well as reducing the loss of ultra-precision components of machine tool due to the collision.
Development and Modeling of a Macro/Micro Composite Positioning System for Microelectronics Manufacturing
Authors: Zhang Lan Yu , Gao Jian , Tang Hui
Published: February 2016

A macro-micro composite positioning stage with high acceleration and high precision is presented in this paper. A linear voice coil motor (VCM) is used to generate the macro motion, and a piezoelectric (PZT) actuator is adopted to drive the micro stage to achieve a precision micro motion, while PZT actuator can also be used to compensate the position error. A high-resolution grating is integrated into the stage to establish the closed-loop feedback. To research the mechanical dynamic characteristic of the stage, the mechanical dynamic model of the macro mechanism and micro mechanism are established, which is based on the rigid-flexible mixed dynamics of mechanical system. The dynamic characteristics of macro motion and micro motion are studied in detail, which is based on the mechanical dynamic simulation of Matlab. The accuracy of the established dynamic model and the performance of the stage are tested by using the scanning laser vibrometer. Both of the simulation results and test results show that the established model can well reflect the dynamic characteristics of the macro-micro composite positioning stage. It also indicates that the developed stage can well achieve a high acceleration and high precision motion, which aims to be applied in microelectronics manufacturing.
The Assessment of Subsurface Damage in Ground Optics by Chemical Etching
Authors: Ye Hui , Yang Wei
Published: February 2016

Optical subsurface damage (SSD), generated from traditional grinding and polishing process, is prone to lower the laser-induced damage threshold (LIDT) of optical elements. Due to the fact that SSD elimination is on the premise of SSD evaluation, numerous SSD characterizing techniques have been proposed in the past few decades. In this paper, various SSD evaluations based on chemical etching technique are described and compared.
Design of the Micro-V-Groove Ultra-Precision CNC Electric Transmission Communication System
Authors: Chen Wei Nan , Liu Guan Feng , Liu Jian Qun
Published: February 2016

In this paper, an electric transmission communication system of micro-V-groove ultra-precision CNC machine with the Mitsubishi PLC is designed. Different from the traditional method using the RS232-BD board, which has to communicate with PLC by programming offline, the system we design connects PC and PLC more directly and is more suitable for micro-V-groove ultra-precision CNC machine tool because of its real time. Embed the communication system in the CNC system, all the external devices can be monitored real-timely and the machine has run successfully.
Spherical Approximation of Free-Form Surface Closed to a Sphere in Semi-Finishing
Authors: Liang Fu Sheng , Zhao Ji , Ji Shi Jun , Wang Xin
Published: February 2016

The free-form surface closed to a sphere of brittle material has been used widely, but it is difficult for machining and the efficiency of processing is insufficient. In order to get a product, several processes are needed, such as rough machining, semi-finishing and finishing. Axisymmetric curved surface can take place of the free-form surface in roughing or semi-finishing for wiping off the mass allowance efficiently. Therefore, a spherical approximation algorithm of free-form surface closed to sphere is presented in which free-form surface optical lens will be replaced by a spherical surface in semi-finishing and get the approximate sphere of the free-form surface. It can be certified in the test that this method is simple and reliable. The efficiency and precision in machining is excellent and the distribution of allowance for finishing is uniform in the whole surface, which has great practical significance in machining of optical free-form surface of brittle materials.
Development of CNC System Software for Micro V-Groove Machine Tool
Authors: Huang Guo Qiang , Liu Jian Qun , Gao Wei Qiang
Published: February 2016

The computerize numerical control (CNC) system is one of the key factors for the development of micro v-groove machine tools to fabrication micro v-groove structures. Based on the investigation on the machining of micro v-groove structures, a developed software contains five modules: editing, automatic programming, program control, manual control and human machine interface. A3200 software based motion controller integrated with the machine characteristics is used in this study to develop the motion control functions of the micro v-groove machine tool. Meanwhile, a method is proposed to redefine the instructions of M, T and S by setting monitoring points so as to enhance the scalability of CNC system. The results show that the CNC system software is not only stable and reliable, but also satisfies the basic requirements of the ultra-precision machining of micro v-groove structures.
Dynamic Conveyor Tracking Control of a Delta Robot
Authors: Zhang Guo Ying , Liu Guan Feng , Guo Xiao Bin , Lin Xie Yuan
Published: February 2016

For general dynamic pick and place tasks that the objects are transferred with high speed by the conveyor belt, the capability of a delta robot to track the traveling objects is very important for the efficiency. To meet the needs of precision and smooth control, a computed-torque control scheme for conveyor tracking is implemented in this paper. For higher efficiency and accuracy, computer vision system, encoder and conveyor belt region are incorporated into the control scheme. Dividing the conveyor belt into three regions, the robot is commanded to track, pick and give up according to the subregions. Conveyor belt is equipped with an encoder that provides the controller with real-time position and speed of the belt. Based upon those informations, the controller automatically compensates the end positions with respect to the belt to adjust for the position of the conveyor. Then, the conveyor tracking problem is converted to a subregional tracking problem.
Research on Deposition Characteristics of the Double-Nozzle in Near-Field Electrospinning
Authors: Wang Zhi Feng , Chen Xin Du , Huang Shen Neng , Fang Fei Yu , Wang Han
Published: February 2016

With the double-nozzle NFES process, the uncertainty is more suitable to investigate than the multi-nozzle NFES and also meet higher liquid throughput requirement than conventional electrospinning. Moreover, the key point is to control the deposition characteristics of double-nozzle NFES under the interaction of the nozzles. This paper simulates the change in electric field intensity with the change of nozzle length and voltage. The experiment shows that the deposition distance becomes smaller when needle length increases, however, the influence of voltage is opposite in certain range. According to the study above, the results could be the guidance of the multi-nozzles NEFS in manufacturing process, and also can illustrate the force distribution of the jet with further modification.
A Novel Format of Depth Map Image
Authors: Chan Chang Yuen , Li Li Hua , Lee Wing Bun , Liu Ya Hui
Published: February 2016

When the micro lens array machined by an ultra-precision machine was used in 3D computer graphics, a novel format of depth map image was invented with adaptively variable data length for multi requirements of different 3D computer graphics applications. A depth map is an image or image channel that contains information relating to the distance of the surfaces of objects a scene from a viewpoint. Depth maps can be applied for many functions: defocusing, rendering of 3D scenes, shadow mapping and other distance information-related applications.
Control of Traumatic Extremity Hemorrhage
Authors: Day Michael W.
Published: February 2016

Although most extremity hemorrhage from trauma can be controlled with direct pressure and/or pressure dressings, the occasional uncontrolled hemorrhage can be life threatening. Tools that may be able to control such life-threatening extremity hemorrhage include hemostatic dressings, tourniquets, and several new devices that have recently become available. Hemostatic dressings, a relatively new concept, incorporate materials that increase coagulation into a dressing that is applied directly to the wound. Although the use of tourniquets has a long history, recent military conflicts have provided numerous studies that supported and refined their use. The novel extremity hemorrhage control devices effectively control bleeding in one of several ways: direct compression, arterial compression above the level of injury, and sealing the wounds’ edges, creating a hematoma.
Sevelamer-associated ischemic colitis with perforation
Authors: Hudacko Rachel , Kaye Peter
Published: February 2016

We present a case of an 83-year-old woman with end-stage renal disease and hyperphosphatemia treated with sevelamer carbonate, who underwent subtotal colectomy for diffuse bowel necrosis and two perforations in the transverse colon. Histologic examination revealed ischemic colitis with crystals consistent with sevelamer carbonate embedded in ulcer debris and within the colonic wall in areas of transmural necrosis. This is a novel cause of drug-induced ischemic colitis with subsequent perforation that has not yet been reported in the literature. Clinicians and pathologists should be aware of the potential complications of sevelamer use and the histologic features of sevelamer-induced colonic injury.
Consensus Statement of Multisocietary Task Force Prescription of physical exercise in the cardiological environment (Third part)
Authors: Giada Franco , Carlon Roberto
Published: February 2016

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Application of the general perceived self-efficacy scale in cardiovascular rehabilitation
Authors: Zotti Anna Maria , Balestroni Gianluigi , Cerutti Paola , Rossi Ferrario Silvia , Angelino Elisabetta , Miglioretti Massimo
Published: February 2016

Psychosocial support, education and self-management are important complements of rehabilitation programs. A central concept in self-management is self-efficacy, which refers to oneself confidence in reaching a desired goal. The General Perceived Self-Efficacy scale (GSE), developed to measure self-efficacy at the broadest level, could be useful in the rehabilitation setting, in order to assess patients’ selfmanagement difficulties as well as to design specific interventions for specific diseases. Aim of this work is to verify the GSE Italian version psychometric properties applied to the rehabilitation setting. Data were analyzed from 395 in-patients attending cardiac (83.8%) and neurological (16.2%) rehabilitation. Cardiac patients suffered from post-MI, CABG or heart-failure; all of the neurological patients suffered from amiotrophic lateral sclerosis (ALS). They were mostly males (84.5%), and the mean age was 55.7 years. Principal component factor analysis confirmed that GSE has a monofactorial structure with internal consistency of .85. As in previous studies, a gender difference emerged. There was no difference in cardiac patients, on the basis of their specific disease, but they showed higher self-efficacy perception compared to ALS patients. The findings confirm that GSE is a valid measure of self-efficacy in settings characterised by different levels of functional abilities, as in cardiac and neurological rehabilitation.
Rehabilitation program in patients with moderate-to-severe intermittent claudication: immediate results and one year follow-up
Authors: Rossini Duccio , Bulckaen Massimo , Di Marco Stefano , Giovannetti Roberto , Giuntoli Franco , Iacopetti Luciana , Vergoni William
Published: February 2016

Background: Physical training is believed the primary treatment of claudication symptoms. Although exercise therapy is self-effective, some drugs improving functional capacity have additive effects. TASC (Trans Atlantic Society Consensus) considers Propionil-L-Carnitine (PLC) and prostaglandin-E1 (PGE1) as poorly studied drugs with potential benefits in improving claudication. This retrospective, observational study was performed to compare the efficacy of PGE1 and PLC, and to evaluate both the immediate results of an intensive, short-course rehabilitation program and the outcome at one year follow-up. Methods: Twenty-five patients with severe-moderate claudication were selected. All patients were subjected to an intensive, supervised exercise program for 4 weeks in combination with either PGE1 (10 patients) or PLC (15 patients). Drugs were infused i.v. before every exercise session: 60 μg PGE1 within 2 hours and 600 mg PLC within 10 minutes. Patients were trained with the same supervised treadmill walking-exercise program. At the end of the rehabilitation period, patients were instructed to keep walking (advised home exercise). Initial claudication distance (ICD) and absolute claudication distance (ACD) were evaluated during a constant treadmill test (3 km/hour speed, 10% grade) at entry, after 4 weeks and at one year follow-up. A patient was considered as no-responder if his/her improvement in ACD was <33%. Results: A significant increase of both ICD and ACD was detected after both 4 weeks (+269% and +135%, respectively, in PGE1 group; +245% and +125%, respectively, in PLC group) and one year (+364% and +202%, respectively, in PGE1 group; +279% and +176%, respectively, in PLC group). No-responder patients after the intensive training period (2 in PGE1 group and 4 in PLC group) remained noresponders also at one year follow-up. Both PGE1 and PLC treatments were well tolerated. No serious drug-related side effect requiring interruption of the treatment was observed. Conclusions: A short-course of intensive exercise treatment plus PLC or PGE1 may enhance walking ability. The result was confirmed at one year follow-up.
Isolation of Circulating Tumor Cells from Multiple Epithelial Cancers with ApoStream®for Detecting (or Monitoring) the Expression of Folate Receptor Alpha
Authors: O'Shannessy Daniel J. , Davis Darren W. , Anderes Kenna , Somers Elizabeth B.
Published: February 2016

This study describes our efforts to further the field of noninvasive diagnostics, specifically in the area of liquid biopsies in oncology. We employed laser scanning cytometry using highly selective antibodies to interrogate circulating tumor cells (CTCs) that were isolated using ApoStream®technology to identify folate receptor alpha (FRα)–positive cells. We demonstrate that FRα+CTCs can be isolated from patients with metastatic cancers, including NSCLC adenocarcinoma, breast cancer, and ovarian cancer, whereas squamous cell lung cancer and normal healthy controls were devoid of FRα+CTCs. We believe that the developed methodology will have applications in both the diagnosis and the monitoring of FRα-expressing cancers. Folate receptor alpha (FRα) expression may have utility as a potential diagnostic and therapeutic target in solid tumors. As tissue samples are not always available for patient screening, this study evaluated a noninvasive assay in CTCs from blood samples to detect FRα expression. The presence of FRα+CTCs enriched using ApoStream®and detected using laser capture cytometry was evaluated in blood samples from cancer patients [NSCLC adenocarcinoma ( n = 14), breast cancer ( n = 20), ovarian cancer ( n = 6), and squamous lung cancer patients ( n = 6)] and healthy subjects ( n = 20). The data demonstrated that FRα+CTCs were detected in blood from NSCLC adenocarcinoma, breast, and ovarian cancer patients, whereas squamous cell lung cancer patients and normal healthy controls lacked FRα+CTCs as previously known. We demonstrate that CTCs captured using ApoStream®can be used to detect FRα+CTCs and may have clinical utility as a real-time liquid biopsy for assessing FRα levels in cancer patients.
Basilic Vein Transposition Used as a Tertiary Vascular Access for Hemodialysis: 15 Years of Experience
Authors: Novotný Róbert , Slavíková Marcela , Hlubocký Jaroslav , Mitáš Petr , Hrubý Jan , Lindner Jaroslav
Published: February 2016

Introduction

The quality of the life in patients requiring long term hemodialysis is directly proportional to the long-term patency of their vascular access. Basilic vein transposition for vascular access (BAVA) represents a suitable option for creating a tertiary native vascular access for hemodialysis on the upper extremities for patients requiring long term hemodialysis. The purpose of the study is to compare BAVAs with arteriovenous grafts (AVG).

Method

Data collection was based on selecting all of the patients with BAVA created in the time period in between January 1996 and August 2011. A questionnaire was created and sent to the selected hemodialysis centers. The resulting set of data was statistically analyzed and evaluated.

Results

In the time period between 1 January 1996 and August 2011, arteriovenous access for hemodialysis was created in 6754 patients (7203 procedures in total). Out of these patients, 175 BAVAs were created. Our patient database of those undergoing the BAVA procedure consisted of 98 females (56%) and 77 males (44%) with an average age of 64.5 years. The prevalence of diabetes mellitus was 60% (105 patients). Primary patency after 12 months was 68.8%, 24 months 59.7%, 36 months 53.8, 48 months 53.8%, and 60 months 50%. Primary assisted patency after 12 months was 89.9%, 24 months 84.6%, 36 months 77.8%, 48 months 77.9%, 60 months 70.8%. Secondary patency after 12 months was 89.4%, 24 months 86.9%, 36 months 81%, 48 months 78.9%, 60 months 75.7%. Twenty-nine BAVAs (16.5%) were obliterated.

Conclusion

Patients benefit from this type of procedure due to the longer patency of a native arteriovenous access, as well as a lower incidence of infectious complications.
C0IPG for a Fourth Order Eigenvalue Problem
Authors: Ji Xia , Geng Hongrui , Sun Jiguang , Xu Liwei
Published: February 2016

This paper concerns numerical computation of a fourth order eigenvalue problem. We first show the well-posedness of the source problem. An interior penalty discontinuous Galerkin method (C0IPG) using Lagrange elements is proposed and its convergence is studied. The method is then used to compute the eigenvalues. We show that the method is spectrally correct and prove the optimal convergence. Numerical examples are presented to validate the theory.
High Order Numerical Methods for the Dynamic SGS Model of Turbulent Flows with Shocks
Authors: Kotov D. V. , Yee H. C. , Wray A. A. , Hadjadj A. , Sjögreen B.
Published: February 2016

Simulation of turbulent flows with shocks employing subgrid-scale (SGS) filtering may encounter a loss of accuracy in the vicinity of a shock. This paper addresses the accuracy improvement of LES of turbulent flows in two ways: (a) from the SGS model standpoint and (b) from the numerical method improvement standpoint. In an internal report, Kotov et al. ( “High Order Numerical Methods for large eddy simulation (LES) of Turbulent Flows with Shocks”, CTR Tech Brief, Oct. 2014, Stanford University), we performed a preliminary comparative study of different approaches to reduce the loss of accuracy within the framework of the dynamic Germano SGS model. The high order low dissipative method of Yee & Sjögreen (2009) using local flow sensors to control the amount of numerical dissipation where needed is used for the LES simulation. The considered improved dynamics model approaches include applying the one-sided SGS test filter of Sagaut & Germano (2005) and/or disabling the SGS terms at the shock location. For Mach 1.5 and 3 canonical shock-turbulence interaction problems, both of these approaches show a similar accuracy improvement to that of the full use of the SGS terms. The present study focuses on a five levels of grid refinement study to obtain the reference direct numerical simulation (DNS) solution for additional LES SGS comparison and approaches. One of the numerical accuracy improvements included here applies Harten's subcell resolution procedure to locate and sharpen the shock, and uses a one-sided test filter at the grid points adjacent to the exact shock location.
Monotone Finite Difference Schemes for Anisotropic Diffusion Problems via Nonnegative Directional Splittings
Authors: Ngo Cuong , Huang Weizhang
Published: February 2016

Nonnegative directional splittings of anisotropic diffusion operators in the divergence form are investigated. Conditions are established for nonnegative directional splittings to hold in a neighborhood of an arbitrary interior point. The result is used to construct monotone finite difference schemes for the boundary value problem of anisotropic diffusion operators. It is shown that such a monotone scheme can be constructed if the underlying diffusion matrix is continuous on the closure of the physical domain and symmetric and uniformly positive definite on the domain, the mesh spacing is sufficiently small, and the size of finite difference stencil is sufficiently large. An upper bound for the stencil size is obtained, which is determined completely by the diffusion matrix. Loosely speaking, the more anisotropic the diffusion matrix is, the larger stencil is required. An exception is the situation with a strictly diagonally dominant diffusion matrix where a three-by-three stencil is sufficient for the construction of a monotone finite difference scheme. Numerical examples are presented to illustrate the theoretical findings.
Dissipação de energia do escoamento deslizante sobre turbilhões em vertedouros em degraus de declividade 1V:1H
Authors: Dai Prá M. , Priebe P.S. , Sanagiotto D.G. , Marques M.G.
Published: February 2016

A dissipação de energia ao longo da calha é a principal função dos vertedouros em degraus. Com essas estruturas se busca a redução da energia residual no pé da barragem, proporcionando menores custos com a construção de estruturas de dissipação a jusante do vertedouro. Este estudo caracteriza a dissipação da energia do escoamento deslizante sobre turbilhões em vertedouros em degraus com declividade de 45° (1V:1H) através da análise experimental em quatro modelos físicos, sendo um com calha lisa e três com calhas em degraus de alturas constantes iguais a 30mm, 60mm e 90mm. Foram avaliados os aspectos relacionados a dissipação de energia do escoamento, especialmente aqueles relacionados aos níveis médios da água nas regiões aeradas e não aeradas do fluxo, permitindo o estabelecimento de parâmetros adimensionais representativos da energia dissipada ao longo da calha em degraus.
La explotación intensa de los acuíferos en la cuenca baja del Segura y en la cuenca del Vinalopó
Authors: Sahuquillo Andrés
Published: February 2016

Los acuíferos carbonatados de la cuenca del Altiplano de Murcia y Vinalopó, junto con algunos otros acuíferos detríticos están siendo explotados muy por encima de su recarga media desde hace casi medio siglo lo que produjo una reducción continua de los niveles de agua subterránea en la mayoría de la región. Hasta casi 5 m/año en algunos casos y más de 300 metros de su situación inicial en alguna zona, con el consiguiente encarecimiento de su explotación. La caída en los niveles produjo el secado de manantiales y humedales y el aumento de la salinidad en algunas zonas causadas por la presencia de formaciones salinas. En contra de estos problemas está el aumento de la riqueza creada por la disponibilidad de agua desde el comienzo de la explotación intensa de los acuíferos. La Directiva Marco del Agua exigía que los acuíferos estuvieran antes de 2015 en buenas condiciones cuantitativas y cualitativas, cosa que no es posible, y tampoco lo sería retrasando esta fecha varias décadas. Análisis sencillos indican que aún eliminando los bombeos, los acuíferos tardarían entre 100 y 1000 años en recuperarse. Se analizan distintos métodos para determinar la recarga y los modelos matemáticos del comportamiento de los acuíferos que podrían utilizarse como herramientas válidas para su gestión. Se discute el papel que en lo sucesivo pueden jugar en la gestión de los recursos de agua.

 
Análisis regional de frecuencia de precipitaciones extremas en el Norte de Mozambique
Authors: Álvarez M. , Puertas J. , Peña E.
Published: February 2016

Las precipitaciones extremas que tienen lugar sobre las cuencas internas de Cabo Delgado (Norte de Mozambique) generan eventos de avenidas que provocan anualmente inundaciones que causan cuantiosas pérdidas materiales, económicas y vidas humanas. Se presenta un estudio de análisis regional de frecuencia de precipitaciones máximas basado en el método del índice de avenida con sus parámetros estimados por los L-momentos. Se ha contado con un total de 12 estaciones pluviométricas con registros de observaciones de más de 20 años. Las medidas de discordancia y heterogeneidad basadas en los L-momentos revelaron que la región de estudio puede ser considerada homogénea. De entre las funciones de distribución candidatas analizadas las simulaciones de Monte Carlo identificaron la función de distribución Logística Generalizada como la de mejor ajuste a escala regional. Los resultados obtenidos pueden ser de utilidad en estudios relacionados con las avenidas y delimitación de zonas inundables de la región.
Two newly observed cases of fish-eating in anubis baboons
Authors: Matsumoto-Oda Akiko , Collins Anthony D.
Published: February 2016

Most non-human primates are omnivorous and eat a wide variety of food types like as fruit, leaves, seeds, insects, gums or a mixture of these items. In spite of frequent eating of fish in human, there are few species to eat fishes in non-human primates. Observations of fish-eating in wild primates bring us an important cue for the question why humans have evolved appetite for fish. Here we report two new fish-eating cases observed in anubis baboons (Papio anubis) at the Mpala Research Centre, Kenya and the Gombe National Park, Tanzania. Both cases were observed in dry seasons, and two adult males and a young female ate recently dead or dying fishes in each case. In these two cases, the opportunity of fish-eating occurred by chance and it will be difficult for them to eat fishes ordinarily.
Size distribution and optical properties of mineral dust aerosols transported in the western Mediterranean
Authors: Denjean C. , Cassola F. , Mazzino A. , Triquet S. , Chevaillier S. , Grand N. , Bourrianne T. , Momboisse G. , Sellegri K. , Schwarzenbock A. , Freney E. , Mallet M. , Formenti P.
Published: February 2016

Abstract. This study presents in situ aircraft measurements of Saharan mineral dust transported over the western Mediterranean basin in June–July 2013 during the ChArMEx/ADRIMED (the Chemistry-Aerosol Mediterranean Experiment/Aerosol Direct Radiative Impact on the regional climate in the MEDiterranean region) airborne campaign. Dust events differing in terms of source region (Algeria, Tunisia and Morocco), time of transport (1–5 days) and height of transport were sampled. Mineral dust were transported above the marine boundary layer, which conversely was dominated by pollution and marine aerosols. The dust vertical structure was extremely variable and characterized by either a single layer or a more complex and stratified structure with layers originating from different source regions. Mixing of mineral dust with pollution particles was observed depending on the height of transport of the dust layers. Dust layers carried a higher concentration of pollution particles below 3 km above sea level (a.s.l.) than above 3 km a.s.l., resulting in a scattering Ångström exponent up to 2.2 below 3 km a.s.l. However, the optical properties of the dust plumes remained practically unchanged with respect to values previously measured over source regions, regardless of the altitude. Moderate absorption of light by the dust plumes was observed with values of aerosol single scattering albedo at 530 nm ranging from 0.90 to 1.00. Concurrent calculations from the aerosol chemical composition revealed a negligible contribution of pollution particles to the absorption properties of the dust plumes that was due to a low contribution of refractory black carbon in regards to the fraction of dust and sulfate particles. This suggests that, even in the presence of moderate pollution, likely a persistent feature in the Mediterranean, the optical properties of the dust plumes could be assumed similar to those of native dust in radiative transfer simulations, modelling studies and satellite retrievals over the Mediterranean. Measurements also showed that the coarse mode of mineral dust was conserved even after 5 days of transport in the Mediterranean, which contrasts with the gravitational depletion of large particles observed during the transport of dust plumes over the Atlantic. Simulations with the WRF mesoscale meteorological model highlighted a strong vertical turbulence within the dust layers that could prevent deposition of large particles during their atmospheric transport. This has important implications for the dust radiative effects due to surface dimming, atmospheric heating and cloud formation. The results presented here add to the observational data set necessary for evaluating the role of mineral dust on the regional climate and rainfall patterns in the western Mediterranean basin and understanding their atmospheric transport at global scale.
Similarity analysis of turbulent transport and dissipation for momentum, temperature, moisture, and CO2 during BLLAST
Authors: Hackerott João A. , Paskyabi Mostafa Bakhday , Kral Stephan T. , Reuder Joachim , de Oliveira Amauri P. , Marques Filho Edson P. , Mesquita Michel d. S. , de Camargo Ricardo
Published: February 2016

Abstract. The budget equation components for turbulent kinetic energy (TKE) and the variances of virtual potential temperature, specific humidity, and specific CO2 content have been estimated using the Inertial Dissipation and Eddy Covariance methods. A discussion with four examples is provided about the normalization used for comparing different tracer spectra, divided by the respective characteristic scale squared. A total of 124 high frequency sample segments of a 30-min period from 20 days of the Boundary Layer Afternoon and Sunset Turbulence field campaign were used in order to provide parameterizations for the dimensionless dissipation and residual (i.e. total transport) components as a function of the Atmospheric Surface Layer (ASL) stability parameter, ζ. The results show a similar linear relation for all tracers variance dissipation components, ΦDχ ≅ 0.4 + 0.2 ζ, during the convective ASL, i.e. −1 < ζ < −0.1. Although parameterizations were also proposed for the dimensionless dissipation rate of TKE and tracer variances during stable ASL, we conclude that in this regime, other mechanisms in addition to ζ may be significantly important. In the stable and near-neutral ASL stability regimes, the transport component for different tracers may not be considered the same. In these conditions, the dissipation component of TKE and tracer variances can have the same magnitude as the other terms in their respective budget equation.
Observations of PAN and its confinement in the Asian Summer Monsoon Anticyclone in high spatial resolution
Authors: Ungermann J. , Ern M. , Kaufmann M. , Müller R. , Spang R. , Ploeger F. , Vogel B. , Riese M.
Published: February 2016

Abstract. This paper presents a set of observations by the CRISTA infrared limb sounder in low-earth orbit taken in August 1997 and analyses of trace-gases in the Asian Summer Monsoon (ASM) region. The spatially highly-resolved measurements of peroxyacetyl nitrate (PAN) and O3 allow a detailed analysis of an eddy-shedding event of the ASM anticyclone.We identify enhanced PAN volume mixing ratios (VMRs) within the main anticyclone and within the eddy, which are suitable as a tracer for polluted air within the ASM originating in India and China. Comparing the retrieved PAN VMRs with potential vorticity (PV) on isentropes reveals that the PAN VMRs exhibit the strongest decrease at each isentrope for an increasing value of PV which may be used to identify the extent of the ASM. Using temperature values also derived from CRISTA measurements, we also computed the location of the thermal tropopause according to the WMO criterion and find that its location agrees well with the limits of the area of increased PAN VMRs both horizontally on isentropes and vertically within the anticyclone. In contrast, the shed eddy exhibits enhanced PAN VMRs for 1 to 2 km above the thermal tropopause. Using the relationship between PAN as a tropospheric tracer and O3 as a stratospheric tracer to identify mixed air parcels, we further found the anticyclone to contain few such parcels, whereas the region in between the anticyclone and the eddy contains many mixed parcels. In combination, this implies that while the anticyclone confines polluted air masses well, eddy shedding provides a very rapid horizontal transport pathway of Asian pollution into the extratropical lowermost stratosphere with a time scale of only a few days.
A statistical study over Europe of the relative locations of lightning and associated energetic burst of electrons from the radiation belt
Authors: Bourriez F. , Sauvaud J.-A. , Pinçon J.-L. , Berthelier J.-J. , Parrot M.
Published: February 2016

Abstract. The DEMETER (Detection of Electro-Magnetic Emissions Transmitted from Earthquake Regions) spacecraft detects short bursts of lightning-induced electron precipitation (LEP) simultaneously with newly injected upgoing whistlers. The LEP occurs within < 1 s of the causative lightning discharge. First in situ observations of the size and location of the region affected by the LEP precipitation are presented on the basis of a statistical study made over Europe using the DEMETER energetic particle detector, wave electric field experiment, and networks of lightning detection (Météorage, the UK Met Office Arrival Time Difference network (ATDnet), and the World Wide Lightning Location Network (WWLLN)). The LEP is shown to occur significantly north of the initial lightning and extends over some 1000 km on each side of the longitude of the lightning. In agreement with models of electron interaction with obliquely propagating lightning-generated whistlers, the distance from the LEP to the lightning decreases as lightning proceed to higher latitudes.
A gridded data set of upper-ocean hydrographic properties in the Weddell Gyre obtained by objective mapping of Argo float measurements
Authors: Reeve K. A. , Boebel O. , Kanzow T. , Strass V. , Rohardt G. , Fahrbach E.
Published: February 2016

Abstract. The Weddell Gyre plays a crucial role in the modification of climate by advecting heat poleward to the Antarctic ice shelves and by regulating the density of water masses that feed the lowest limb of the global ocean overturning circulation. However, our understanding of Weddell Gyre water mass properties is limited to regions of data availability, primarily along the Prime Meridian. The aim of this paper is to provide a data set of the upper water column properties of the entire Weddell Gyre. Objective mapping was applied to Argo float data in order to produce spatially gridded, time-composite maps of temperature and salinity for fixed pressure levels ranging from 50 to 2000 dbar, as well as temperature, salinity and pressure at the level of the sub-surface temperature maximum. While the data are currently too limited to incorporate time into the gridded structure, the data are extensive enough to produce maps of the entire region across three time-composite periods (2001–2005, 2006–2009 and 2010–2013), which can be used to determine how representative conclusions drawn from data collected along general RV transect lines are on a gyre scale perspective. The work presented here represents the technical prerequisite for addressing climatological research questions in forthcoming studies. The data sets are available in netCDF format at doi:10.1594/PANGAEA.842876.
Joint inference of groundwater–recharge and hydraulic–conductivity fields from head data using the ensemble Kalman filter
Authors: Erdal D. , Cirpka O. A.
Published: February 2016

Abstract. Regional groundwater flow strongly depends on groundwater recharge and hydraulic conductivity. Both are spatially variable fields, and their estimation is an ongoing topic in groundwater research and practice. In this study, we use the ensemble Kalman filter as an inversion method to jointly estimate spatially variable recharge and conductivity fields from head observations. The success of the approach strongly depends on the assumed prior knowledge. If the structural assumptions underlying the initial ensemble of the parameter fields are correct, both estimated fields resemble the true ones. However, erroneous prior knowledge may not be corrected by the head data. In the worst case, the estimated recharge field resembles the true conductivity field, resulting in a model that meets the observations but has very poor predictive power. The study exemplifies the importance of prior knowledge in the joint estimation of parameters from ambiguous measurements.
Vegetative impacts upon bedload transport capacity and channel stability for differing alluvial planforms in the Yellow River Source Zone
Authors: Li Z. W. , Yu G. A. , Brierley G. , Wang Z. W.
Published: February 2016

Abstract. The influence of vegetation upon bedload transport and channel morphodynamics is examined along a channel stability gradient ranging from meandering through anabranching through anabranching-braided to fully braided planform conditions along trunk and tributary reaches of the Upper Yellow River in western China. Although the regional geology and climate are relatively consistent across the study area, there is a distinct gradient in the presence and abundance of riparian vegetation for these reaches atop the Qinghai-Tibet Plateau (elevations in the study area range from 2800–3400 m a.s.l.). The hydraulic and geomorphic role of riparian vegetation varies as follows: trees exert the strongest influence in the anabranching reach, the meandering reach flows through meadow vegetation, the anabranching-braided reach has a grass, herb, and sparse shrub cover, and the braided reach has no riparian vegetation. A non-linear relation between vegetative cover on the valley floor and bedload transport capacity is evident, wherein bedload transport capacity is highest for the anabranching reach, followed by the anabranching-braided, braided and meandering reaches respectively. The relationship between the bedload transport capacity of a reach and sediment supply from upstream exerts a significant influence upon channel stability. Bedload transport capacity during the flood season (June–September) in the braid ed reach is much less than the rate of sediment supply, inducing bed aggradation and dynamic channel adjustments. Rates of channel adjustment are less pronounced for the anabranching-braided and anabranching reaches, while the meandering reach is relatively stable (i.e. this is a passive meandering reach).
A Bayesian Consistent Dual Ensemble Kalman Filter for State-Parameter Estimation in Subsurface Hydrology
Authors: Ait-El-Fquih B. , Gharamti M. E. , Hoteit I.
Published: February 2016

Abstract. Ensemble Kalman filtering (EnKF) is an efficient approach to addressing uncertainties in subsurface groundwater models. The EnKF sequentially integrates field data into simulation models to obtain a better characterization of the model's state and parameters. These are generally estimated following joint and dual filtering strategies, in which, at each assimilation cycle, a forecast step by the model is followed by an update step with incoming observations. The Joint-EnKF directly up-dates the augmented state-parameter vector while the Dual-EnKF empirically employs two separate filters, first estimating the parameters and then estimating the state based on the updated parameters. To develop a Bayesian consistent dual approach and improve the state-parameters estimates and their consistency, we propose in this paper a one-step-ahead (OSA) smoothing formulation of the state-parameter Bayesian filtering problem from which we derive a new dual-type EnKF; the Dual-EnKF OSA. Compared with the standard Dual-EnKF, it imposes a new update step to the state, which is shown to enhance the performance of the dual approach with almost no increase in the computational cost. Numerical experiments are conducted with a two-dimensional synthetic groundwater aquifer model. Assimilation experiments are performed to assess the performance and robustness of the proposed Dual-EnKF OSA, and to evaluate its results against those of the Joint- and Dual-EnKFs. The proposed scheme is able to successfully recover both the hydraulic head and the aquifer conductivity, further providing reliable estimates of their uncertainties. It is further found more robust to different assimilation settings, such as the spatial and temporal distribution of the observations, and the level of noise in the data. Based on our experimental setups, it yields up to 25 % more accurate state and parameters estimates than the joint and dual approaches.
Technical Note: Advances in flash flood monitoring using UAVs
Authors: Perks M. T , Russell A. J , Large A. R. G
Published: February 2016

Abstract. UAVs have the potential to capture information about the earth's surface in dangerous and previously inaccessible locations. Through image acquisition of flash flood events and subsequent object-based analysis, highly dynamic and oft- immeasurable hydraulic phenomenon may be quantified at previously unattainable spatial and temporal resolutions. The potential for this approach to provide valuable information about the hydraulic conditions present during dynamic, high-energy flash floods has until now not been explored. In this paper we adopt a novel approach, utilising the Kande–Lucas–Tomasi (KLT) algorithm to track features present on the water surface which are related to the free-surface velocity. Following the successful tracking of features, a method analogous to the vector correction method has enabled accurate geometric rectification of velocity vectors. Uncertainties associated with the rectification process induced by unsteady camera movements are subsequently explored. Geo-registration errors are relatively stable and occur as a result of persistent residual distortion effects following image correction. The apparent ground movement of immobile control points between measurement intervals ranges from 0.05–0.13 m. The application of this approach to assess the hydraulic conditions present in Alyth Burn, Scotland during a 1 : 200 year flash flood resulted in the generation of an average 4.2 measurements m−2 at a rate of 508 measurements s−1. Analysis of these vectors provide a rare insight into the complexity of channel-overbank interactions during flash floods. The uncertainty attached to the calculated velocities is relatively low with a spatial average across the area of ±0.15 m s−1. Little difference is observed in the uncertainty attached to out-of-bank velocities (±0.15 m s−1), and within-channel velocities (±0.16 m s−1), illustrating the consistency of the approach.