bluuebunny/crossref_metadata_2025 huggingface dataset:
Navigating the Boundaries of Emergency Department Care: Addressing the Medical and Social Needs of Patients Who Are Homeless
Authors: Doran Kelly M. , Vashi Anita A. , Platis Stephanie , Curry Leslie A. , Rowe Michael , Gang Maureen , Vaca Federico E.
Published: October 2013

Objectives. We sought to understand interpersonal and systems-level factors relevant to delivering health care to emergency department (ED) patients who are homeless.

Methods. We conducted semistructured interviews with emergency medicine residents from 2 residency programs, 1 in New York City and 1 in a medium-sized northeastern city, from February to September 2012. A team of researchers reviewed transcripts independently and coded text segments using a grounded theory approach. They reconciled differences in code interpretations and generated themes inductively. Data collection and analysis occurred iteratively, and interviews continued until theoretical saturation was achieved.

Results. From 23 interviews, 3 key themes emerged: (1) use of pattern recognition in identifying and treating patients who are homeless, (2) variations from standard ED care for patients who are homeless, and (3) tensions in navigating the boundaries of ED social care.

Conclusions. Our study revealed practical and philosophical tensions in providing social care to patients in the ED who are homeless. Screening for homelessness in the ED and admission practices for patients who are homeless are important areas for future research and intervention with implications for health care costs and patient outcomes.
Novel Technique and Guidelines for Measuring Reservoir Pressures in Tight Formations
Authors: Edelman Jeff , Shah Shabbir H. , Ahmed Ramy , Awadalla Tarek
Published: October 2013

It is very challenging to measure formation pressure in the low mobility formations of Eastern Desert, Egypt. The measured mobilities ranged from 0.01 to 5 mD/cP; making the acquisition of reliable formation pressure with conventional pretesting very difficult. Many pretests end up being recorded as ‘Dry’, ‘Tight’ and ‘Supercharged’. However, by exploiting the extreme limits of new generation formation testers such as low volume and relatively lower rates, we were able to overcome these difficulties and record valuable formation pressures.

The electromechanically controlled formation tester is specifically engineered for only pressure and mobility testing as opposed to multifunctional formation tester tool that also collects samples. The two important distinctions of this tool are an electromechanically controlled pressure pretest system that enables precise pretest volume and rate. This is in contrast to the hydraulically driven pretest mechanisms in conventional tools. Secondly, because the tool is devoted only to pretesting, it has a very small flowline volume with very tight mechanical construction. The required decompression volume is much smaller than conventional tools, brings new efficiency to the formation pressure testing process by significantly reducing both the time and risk involved with wireline formation testing operation.

The operating guidelines is prepared to recognize pressure measurement challenges in low mobility formations, it may assist engineers to identify the problems and take corrective measures by altering pretest volume and rate. Correct practice of taking right volume and rate may bring value to pretests whereas inexperience of pressure measurement in low mobility formations may cause significant damage to the data quality. Herein we have presented examples of good quality pretests changing into ‘Dry’ or ‘Tight’ by taking high volumes and also conversely the ‘Dry’ or ‘Tight’ pretests converting into good quality by optimizing pretest volumes.
Nitrogen Foam Flooding Test for Controlling Water Cut and Enhance Oil Recovery in Conventional Oil Reservoirs of China Offshore Oilfield
Authors: Ma Kuiqian , Jia Xiaofei , Yang Jing , Liu Yingxian , Liu Zongbin
Published: October 2013

SZ oilfield was put on production in China Bohai Bay in 1993, characterized by huge thickness, high permeability, severe heterogeneity and high oil viscosity (24-452cp). There are many challenges during water injection because high oil-water viscosity ratio leads to quick breakthrough of injected water, high increasing rate of water cut, and so on. In order to solve these problems, nitrogen foam flooding was conducted in SZ oilfield during 2010 to 2011. Before pilot test, laboratory experiments and reservoir numerical simulation study under field conditions were conducted to evaluate the performance of different foaming agent and foam stabilizing agent, blocking performance of foam systems with different gas-liquid ratio and injection method, the influences of reservoir heterogeneity, connectivity, water cut time on nitrogen foam flooding efficiency. The study shows that the rational gas-liquid ratio in SZ oilfield is 1:1-3:1, the optimum concentration of foam agent is 3000- 5000mg/L, the optimum foam stabilizing agent concentration is 700-1000mg/L, and the injection method should be mixed injection. The more heterogeneous, more connective, higher water cut the porous media is, the higher the increment of oil recovery and the better the efficiency of foam displacement.

The Hall curve analysis was used to evaluate the effectiveness of injection well and to calculate the resistance factor (RF) & residual resistance factor (RRF) (RF from 1.22 to 2.88, RRF from 1.06 to 2.00). The decline curve analysis was also used to obtain net incremental oil. Results from two well patterns conducted nitrogen foam flooding in 2011 indicate that water cut reduction ranged from 3.2 to 14.5%, accumulative oil production increases 30283m3 in a year and enhanced the oil recovery of the pilot about 0.5%, which suggests that nitrogen foam flooding has good prospect in conventional heavy oil reservoirs of china offshore oilfield.
Characterisation of Bowen Basin Coal Shrinkage and Geomechanical Properties and Their Influence on Reservoir Permeability
Authors: Connell Luke D , Mazumder Saikat , Marinello Stephen , Sander Regina , Camilleri Michael , Pan Zhejun , Heryanto Deasy
Published: October 2013

Coal reservoirs have a dual porosity, naturally fractured structure. As in other naturally fractured formations coal permeability is sensitive to the effective stress, decreasing exponentially as the effective stress increases. In contrast to other naturally fractured reservoirs, coal shrinks as gas desorbs. This shrinkage plays an important role in determining reservoir permeability behaviour as it leads to a geomechanical response that counteracts the effective stress increase due to the pore pressure drawdown during production. It has been shown that under the right conditions this shrinkage effect can lead to a rebound in the reservoir permeability.

There are a range of existing models for coal reservoir permeability behaviour that represent the coupled effects of pore pressure change and shrinkage, with the models by Shi and Durucan (2004, 2005) and Palmer and Mansoori (1996, 1998) finding widespread use. An important obstacle to the meaningful application of coal permeability models is characterisation of the various physical properties involved. There are also important questions about the behaviour of these properties with changes in pressure and effective stress. For example, many coal permeability models assume that the cleat compressibility and geomechanical properties are constant. This paper presents the results of a laboratory program of work to measure the coal properties that influence absolute reservoir permeability during gas production; these are matrix shrinkage, cleat compressibility, and the geomechanical properties (see Figure 1). These measurements were made on core samples from the Bowen Basin of Australia, an important area for coal seam methane production. The results are compared to the field based analyses of Mazumder et al. (2012).
Geomechanical Optimisation with Managed Pressure Drilling for Successfully Penetrating Challengeable Depleted Reservoirs in Offshore Sarawak, Malaysia
Authors: Fang Zhi , White Adrian , Tjengdrawira Agus , Ashat Fuad , Lee Chan Fong , Vince Tilley
Published: October 2013

Drilling new development or infill wells in a mature shallow water field, offshore Sarawak, Malaysia, is challenging. Reservoir depletion reduces the fracture gradient to a level such that drilling and cementing operations risk hydraulically fracturing the wellbore. To compound matters, intra-reservoir claystone sections are weak and require higher mud weights to maintain wellbore stability. As a result, the operational mud-weight window becomes very narrow, and drilling operations will be challenging using conventional drilling technologies. Without prior quantification of the operational mud window there is an increased risk of wellbore instability, lost circulation, and even loss of the hole.

A geomechanical study was undertaken for the field to understand the evolution of the fracture gradient due to depletion of the multiple sandstone reservoirs, the drilling risks associated with the large amounts of depletion, and to quantify operational mud- weight windows. The study used drilling and wireline log data from offset wells to derive the in situ stresses, formation pressures, androck strength properties. The results show that a tight drilling mud window exists through many of the depleted reservoirs, but these narrow mud-weight windows could be widened by casing off interim reservoirs that have undergone high depletion. The results were integrated into the final drilling plan. As a consequence, the managed pressure drilling was optimised to cope with narrow mud-weight windows, improving the capability of drilling the new well to total depth. This paper describes the practical geomechanical workflow that assists in understanding the drilling challenges in the depleted shallow water field and how the results should be adopted in well planning and drilling operations. The integrated geomechanical study and managed pressure drilling practice provide a feasible approach to mitigate drilling risks and minimise drilling costs. This approach can play a significant role in the wellplanning and drilling management of challenging depleted reservoirs.
A Dynamic Split Method to Predict Development Index in Heterogeneous Waterflooding Oil Field
Authors: Feng Qi-Hong , Wang Xiang , Wang Bo , Guo Long-Fei , Wang Duan-ping , Jia Jun-shan , Huang Ying-song
Published: October 2013

Considering the actual conditions of irregularity well arrangement and heterogeneity in reservoir, on the base of reservoir engineering theory, a method to predict residual oil distribution and dynamic development indexes has been proposed. The method first split the oil field into multiple units dynamically and each unit can be equivalent to homogeneous one, using the Buckley-Leverett waterflood theory to predict the dynamic development indexes of every unit and then calculate the entire reservoir development indicators. The oil saturation distribution was calculated by an interpolation algorithm.

The new method is used in three examples to comprehensively analyze the reliability, which include a nine-point homogeneous reservoir and a five-point heterogeneous reservoir and a full-field heterogeneous reservoir with irregular well pattern. Numerical simulation method is also used as contrast experiment in this paper. The results calculated by the two methods are matched relatively well in water cut and oil saturation distribution. In addition, reservoir models of different sizes are established to test the computational efficiency of the new method. Compared with the numerical simulation method, the new method speeds up the procedure more than tens of times.

The new method is of great significance to field application. Well placement optimization with stochastic optimization algorithms requires a large number of function evaluations, each of which entails a simulation run. The computational expense can be reduced by using the new method instead of the numerical simulation method to calculate objective function.
Molecular Diffusion of CO2 From Carbonated Water (CW) Into the Oil – Experimental Observations
Authors: Peksa Anna E. , Wolf Karl-Heinz A. , Zitha Pacelli L.
Published: October 2013

Carbonated Water Flooding (CWF), an alternative enhanced oil recovery (EOR) method in which an oil reservoir is flooded with CO2-enriched water, can be considered as a promising solution for mobilization and recovery of residual oil in water wet rock. At the same time it is a possible mitigation option for an increasing CO2 concentration in the atmosphere and an opportunity for permanent and safe disposal of CO2 underground. One of the important aspects of the CWF process is molecular diffusion of CO2 from carbonated water into oil (DCWO). The process benefits from oil viscosity reduction, an increase in oil relative permeability and, as a result, enhancement of oil mobility. In contrast to many previous studies on the diffusion of carbon dioxide directly into oil by CO2 flooding, DCWO characterization is underexposed in laboratory work and literature. In order to understand the distribution of the total dissolved CO2 between the coexisting phases water and oil, we examine DCWO in experiments by visualization of oil swelling and recovery over time.

To determine the phase behavior of the system, pore-scale diffusion experiments are conducted. In these experiments oil is initially placed in a dead-end pore and covered with water presumed to be from the first secondary recovery phase. Swelling of oil due to CO2 diffusion from a CO2 source, either a CW stream or a pure CO2 stream under P, T-conditions, have been recorded and visualized over time. As a result, pressure and oil-composition dependent, recovery of oil occurs. Based on the results we determined a dominant role of diffusion in the CW recovery process. Existence of ample contact time for water rupture was obtained. In the pore scale water barrier, its geometry (especially – the interfacial area) appears to be a limiting factor. At field scale, time in the range of hours does not play an important role in the overall recovery; however it is of importance for near well injection area.

The results and visualizations of the conducted experiments will contribute to a better understanding of processes such as molecular diffusion in CWF, which will occur. In addition, DCWO results lead to process improvements for achieving recovery in both laboratory core floods and in the field, with an option for CO2 sequestration.
Coil Tubing Furan Resin Sand Consolidation Treatment on Multi Layered Formation in Peninsular Malaysia
Authors: Keith Cheong Ing , Azman Aulfah , Wijoseno Danny Aryo , Kasim Mohamed Heikal , Ishak Mohd Fakhrurazi , Reduan Mohd Z.
Published: October 2013

Excessive sand production is the most common problem in both upstream & downstream processes in oil & gas production facilities. In Peninsular Malaysia, several methods were introduced to resolve this problem ranging from choke management, wellbore sand cleanout and even utilizing screen technology to keep the sand in the formation. However, all those methods are still not considered to be an effective solution to get a long lasting permanent result. By utilizing the furan resin as a sand consolidation treatment chemical, emphasis is given to solve the sand issues from the matrix formation side instead of focusing on the wellbore side as typically done. This results in a treatment that was previously almost impossible to execute but now ingeniously made possible. For every chemical treatment, the challenge lies in how to ensure it will effectively treat the targeted zone especially in multi layered formations which is a characteristic of most of Peninsular Malaysia’s fields.

This paper discusses the success story of this sand consolidation treatment utilizing Coil Tubing as a fluid conveyance tool combined with an inflatable packer to selectively treat the targeted zone. The furan resin properties will also be discussed as one of the key success factors in this sand control method for one of Malaysia’s most challenging fields.
A New Generation Reservoir Simulator and Its Application in a Mature Water-Flooding Oilfield
Authors: Li Qiaoyun , Wu Shuhong , Wang Baohua , Li Xiaobo , Li Hua , Zhang Jiqun , Meng Lixin
Published: October 2013

Reservoir numerical simulation, which interests a large amount of reservoir engineers, is an important tool in oilfield development researches. This paper introduces a new generation simulator, which can be used to simulate the traditional and pseudo-compositional reservoirs. This simulator adopts finite volume method, completely implicit time discretization technology (CITDT) and dynamic space discretization technology (DSDT). The multilevel preconditioner solver, which is applied in the simulator, can enhance the computation speed. In this paper, a mature heterogeneous water-flooding oilfield with 30a’s development history is simulated by this simulator. In the course of development, there are 242 producers and injectors drilled, and the exploitation strata-series are adjusted frequently. Currently the reservoir has entered the "double high" stage, more than 79% of recoverable reserves have been produced and the water-cut reaches to 90%. After history- matching and production prediction by this simulator, the results shows that this reservoir numerical simulator can be used to simulate the complex reservoirs with long development history and mounts of wells, and it can describe the production performance precisely. Moreover, the case study indicated that the new generation simulator is a fast and adaptable tool to simulate the complex reservoirs with large scale, which shows its high potentiality in industrial application.
Intra-oral mandibular sagittal osteotomy technique to correct mandibular distocclusion and mesio-occlusion
Authors: Gioso M. A. , Carvalho P. E. G. , Cunha F. P. , Martinez L. A. V. , Lemos L. S. , Carvalho V. G. G.
Published: October 2013

Skeletal malocclusions may be due to disturbances in the growth of the mandible or maxilla. In most cases, discomfort is the result of tooth-to-tooth malocclusion or tooth-to-softtissue contact. Currently, in veterinary medicine, these problems are treated palliatively. In humans, orthognathic surgery is indicated to correct severe skeletal malocclusions, offering aesthetic and functional benefits to the patients. This research evaluated the effects of an intra-oral mandibular sagittal split osteotomy in 20 dog cadavers with skeletal malocclusion. After sagittal osteotomy and mandibular repositioning, the osteotomies were fixed with titanium mini-plates and 1.5 mm diameter screws or 1.5 mm bicortical screws. The statistical analysis revealed a significant occlusion difference in the treated cadavers (Wilcoxon test, p <0.05). In 19/20 cadavers there was correction of the angular osteotomy while the mandibular alveolar vessels and nerve were preserved during osteotomy and fixation in all cadavers. In conclusion, intra-oral mandible sagittal osteotomy allowed correction of malocclusion in cadavers. However, it would be important to prepare a preoperative orthodontic-surgical treatment plan to obtain a satisfactory occlusion during the surgery in clinical patients.
TRACKING OF HEAD POSITION RELATIVE TO THE SCREEN USING HEAD MOUNTED CAMERA / GALVOS POZICIJOS NUSTATYMAS EKRANO ATŽVILGIU NAUDOJANT ANT GALVOS PRITVIRTINTĄ KAMERĄ
Authors: Borcovas Evaldas , Daunys Gintautas
Published: October 2013

In this paper head position locating systems were analyzed. There were reviewed scientific articles with different proposed methods. The chosen system is with the camera located on the user head. The main parameters of the head positioning systems were analyzed. The procedure laid down in what order parameters are found. The diagram of the system and detail block diagram of the algorithm were provided. Realization of the algorithm used: edge detection method (Sobel), the adjustment algorithm (Subpixel). System is realized in Matlab and C# environment. Determine the optimal parameters for the algorithm execution. Execution of the algorithm in Matlab environment is 1.2 s and C # environment – 126 ms. During the examination of the longest executing algorithm segment, it was found that image filtering is carried out in 107 ms. It is noted that the uncertainty of the algorithm can be divided into static and measurement. The maximum static uncertainty while measuring head position parameters is 1.63 mm and orientation parameters – 0.16°. The maximum measurement uncertainty while measuring head position parameters is 4 mm and orientation parameters – 0.11°.

Santrauka

Nagrinėjamos galvos padėties pozicionavimo sistemos. Apžvelgti moksliniai straipsniai, kuriuose pateikiami įvairūs siūlomi metodai. Pasirinkta sistema, kai kamera pritvirtinama vartotojui ant galvos. Išskirti pagrindiniai galvos padėties nustatymo parametrai, nustatytas parametrų suradimo eiliškumas, pateikta sistemos schema ir detali algoritmo blokinė schema. Algoritmui įgyvendinti taikyti briaunų radimo (Sobel) ir algoritmo tikslinimo (Subpixel) metodai. Sistema įgyvendinta Matlab ir C# aplinkose. Nustatyti optimalūs algoritmo vykdymo parametrai. Naudojamo kompiuterio procesorius Intel Pentium dual core T4500 – 2,3 GHz. Vidutinis algoritmo veikimo laikas Matlab aplinkoje yra 1,2 s, o C# aplinkoje – 126 ms. Ištyrus algoritmo segmentų vykdymo laiką, pastebėta, kad ilgiausiai vykdomas vaizdo filtravimas – 107 ms. Parodyta, kad algoritmo neapibrėžtis galima suskirstyti į statines ir matavimo neapibrėžtis. Maksimali statinė neapibrėžtis, matuojant galvos pozicijos padėtį, yra 1,63 mm, matuojant orientacijos parametrus – 0,16°. Maksimali matavimo neapibrėžtis yra 4,0 mm, matuojant galvos padėties parametrus, ir 0,11° – orientacijos parametrus.
CONTROL OF THE HEXAPOD WALKING ROBOT / ŠEŠIAKOJO ŽINGSNIUOJANČIO ROBOTO VALDYMAS
Authors: Zubavičius Raimondas , Paulauskas Nerijus , Šapurov Martynas
Published: October 2013

The analysis focuses on control features of the hexapod walking robot with three degree-of-freedom legs. This paper describes different servo control methods and presents the developed algorithm for formation of servos control signals. The geometric inverse kinematics method was used to calculate the angles of each joint of a leg. The authors present the results of the experimental investigation on the hexapod robot leg movement trajectory.

Article in Lithuanian.

Santrauka

Nagrinėjami šešiakojo žingsniuojančio roboto kojų, turinčių tris judrumo laipsnius, valdymo ypatumai. Aprašomi skirtingi valdomųjų mechanizmų valdymo būdai, pateikiamas sudarytas programos algoritmas valdomųjų mechanizmų valdymo signalams formuoti. Aprašyta, kaip randami atskirų roboto kojos dalių tarpusavio kampai taikant geometrinį atvirkštinės kinematikos metodą. Pateikiami šešiakojo žingsniuojančio roboto maketo tyrimo vienos kojos judėjimo erdvėje rezultatai.
ANALYSIS OF VOLTAGE FORMING METHODS FOR MULTIPHASE INVERTERS / DAUGIAFAZIŲ DAŽNIO KEITIKLIŲ ĮTAMPOS FORMAVIMO METODŲ ANALIZĖ
Authors: Lipinskis Tadas
Published: October 2013

The article discusses advantages of the multiphase AC induction motor over three or less phase motors. It presents possible stator winding configurations for a multiphase induction motor. Various fault control strategies were reviewed for phases feeding the motor. The authors propose a method for quality evaluation of voltage forming algorithm in the inverter. Simulation of a six-phase voltage source inverter, voltage in which is formed using a simple SPWM control algorithm, was performed in Matlab Simulink. Simulation results were evaluated using the proposed method. Inverter’s power stage was powered by 400 V DC source. The spectrum of output currents was analysed and the magnitude of the main frequency component was at least 12 times greater than the next biggest-magnitude component. The value of rectified inverter voltage was 373 V.

Article in Lithuanian.

Santrauka

Straipsnyje pristatomi daugiafazių variklių pranašumai, palyginus su trifaziais ir vienfaziais. Apžvelgiama variklių sandara ir pristatomi daugiafazių variklių apvijų tipai. Pristatomos variklių valdymo strategijos sugedus apvijos ar inverterio galios pakopos raktui. Pasiūloma daugiafazių dažnio keitiklių įtampos formavimo algoritmų vertinimo metodika. Matlab Simulink terpėje modeliuojamas šešiafazis dažnio keitiklis, kuriame veikia sinusinio impulso skvarbos moduliavimo įtampos formavimo algoritmas. Pagal sukurtą vertinimo metodiką įvertinami dažnio keitiklio modeliavimo rezultatai, pateikiamos išvados.
AUTOMATINIO VALDYMO SISTEMŲ SU VĖLINIMO GRANDINĖMIS SINTEZĖS METODAI / METHODS OF SYNTHESIS OF AUTOMATIC CONTROL SYSTEMS WITH DELAY
Authors: Lapeta Aliaksandr
Published: October 2013

The paper investigates the procedure for introduction of systems containing delay elements. Shortcomings and difficulties in the synthesis of regulators and precompensators of control systems with delays in output and control channel where determined. The author focused on two approaches for the formation of promatrix and synthesis of control systems, considering the factor of delay.

Santrauka

Straipsnyje tiriama sistemų su vėlinimo elementais įterpimo procedūra. Išanalizuoti valdymo sistemų, reguliatorių ir kompensavimo grandžių su vėlinimo elementais išėjime ir valdymo kanale sintezės sudėtingumo aspektai ir trūkumai. Aptarti du promatricų formavimo ir valdymo sistemų sintezės, įvertinant valdomojo objekto vėlinimą, formavimo būdai.

Straipsnis anglų kalba.
ALL DIGITAL PHASE-LOCKED LOOP / VISIŠKAI SKAITMENINĖ FAZĖS DERINIMO KILPA
Authors: Jurgo Marijan
Published: October 2013

The paper reviews working principles of phase-locked loop and drawbacks of classical PLL structure in nanometric technologies. It is proposed to replace the classical structure by all-digital phase-locked loop structure. Authors described the main blocks of all-digital phase-locked loop (time to digital converter and digitally controlled oscillator) and overviewed the quantization noise arising in these blocks as well as its minimization strategies. The calculated inverter delay in 65 nm CMOS technology was from 8.64 to 27.71 ps and time to digital converter quantization noise was from −104.33 to −82.17 dBc/Hz, with tres = 8.64–27.71 ps, TSVG = 143–333 ps, FREF = 20–60 MHz.

Article in Lithuanian.

Santrauka

Nagrinėjama fazės derinimo kilpa (FDK), jos veikimas, klasikinės struktūros FDK trūkumai nanometrinėse technologijose, galimi jų sprendimo būdai. Siūlomas perėjimas prie visiškai skaitmeninės fazės derinimo kilpos. Aprašomi pagrindiniai visiškai skaitmeninės FDK blokai – laikinis skaitmeninis keitiklis (LSK) ir skaitmeniniu būdu valdomas generatorius (SVG). Aptariamas LSK ir SVG atsirandantis kvantavimo triukšmas ir jo mažinimo priemonės. Apskaičiuota 65 nm KMOP technologijoje pasiekiama inverterio vėlinimo trukmė, lygi nuo 8,64 iki 27,71 ps, ir LSK triukšmo lygis, lygus nuo −104,33 iki −82,17 dBc/Hz, kai inverterio vėlinimo trukmė t res = 8,64–27,71 ps, SVG generuojamo signalo periodas TSVG = 143–333 ps, o atraminio signalo dažnis FREF = 20–60 MHz.
CONSTANT SLIP CONTROL SYSTEM OF AN ASYNCHRONOUS MOTOR / PASTOVAUS SLYDIMO ASINCHRONINIO ELEKTROS VARIKLIO ROTORIAUS GREIČIO VALDYMO METODAS
Authors: Šapurov Martynas , Zubavičius Raimondas , Bleizgys Vytautas
Published: October 2013

Asynchronous motors are efficiently controlled using the scalar method. Main problems appear when the motor is fully loaded and desired rotation speed is slow. In such cases, the motor slip exceeds the magnitude of the nominal slip, causing the increase in stator current. The constant slip method was designed to control hardly loaded asynchronous motor. In this particular situation, the constant slip method provides a better efficiency than the scalar method. The magnitude of the motor current refers to the slip: the less is the slip, the less is the magnitude. It is impossible to find the optimal slip for minimization of current with the help of a model. Therefore, the nominal slip value was used as optimal. Article in Lithuanian. Santrauka Pasiūlytas pastovaus slydimo asinchroninio elektros variklio rotoriaus greičio valdymo metodas ištirtas modeliuojant, gauti rezultatai palyginti su skaliarinio valdymo metodo tyrimo rezultatais. Tyrimo rezultatai parodė, kad pastovaus slydimo asinchroninio variklio greičio valdymo metodas yra pranašesnis už skaliarinio valdymo metodą, kai valdomo variklio greitis yra nedidelis ir jo apkrova yra artima nominaliajai.
VOICE QUALITY IN MOBILE TELECOMMUNICATION SYSTEM / BALSO KOKYBĖ MOBILIOJO RYŠIO SISTEMOSE
Authors: Stankevičius Evaldas
Published: October 2013

The article deals with methods measuring the quality of voice transmitted over the mobile network as well as related problem, algorithms and options. It presents the created voice quality measurement system and discusses its adequacy as well as efficiency. Besides, the author presents the results of system application under the optimal hardware configuration. Under almost ideal conditions, the system evaluates the voice quality with MOS 3.85 average estimate; while the standardized TEMS Investigation 9.0 has 4.05 average MOS estimate. Next, the article presents the discussion of voice quality predictor implementation and investigates the predictor using nonlinear and linear prediction methods of voice quality dependence on the mobile network settings. Nonlinear prediction using artificial neural network resulted in the correlation coefficient of 0.62. While the linear prediction method using the least mean squares resulted in the correlation coefficient of 0.57. The analytical expression of voice quality features from the three network parameters: BER, C / I, RSSI is given as well.

Article in Lithuanian.

Santrauka

Nagrinėjama mobiliuoju tinklu perduoto balso kokybės matavimo metodikos problematika, balso kokybės įvertinimo algoritmų pasirinkimo galimybės. Aptariamas sukurtos balso kokybės matavimo sistemos tinkamumas, efektyvumas. Pateikiami sukurtos sistemos taikymo rezultatai parinkus optimalią įrangos konfigūraciją. Sąlygomis, artimomis idealioms, gauta, kad sukurta sistema balso kokybę įvertina vidutiniu 3,85 MOS įverčiu, o standartizuota TEMS Investigation 9.0 – vidutiniu 4,05 MOS įverčiu. Aptarta balso kokybės prognozatoriaus sukūrimo galimybė. Ištirtas balso kokybės priklausomybės nuo mobiliojo tinklo parametrų prognozatorius, taikantis tiesinės ir netiesinės prognozės būdus. Netiesinė prognozė, taikant dirbtinius neuronų tinklus, teikia 0,62 koreliacijos koeficientą. Tiesinė prognozė mažiausiųjų kvadratų metodu teikia 0,57 koreliacijos koeficientą. Gauta analitinė balso kokybės funkcijos išraiška nuo trijų tinklo parametrų: BER, C/I, RSSI.
DATA TRANSFER THROUGHPUT RESEARCH OVER MOBILE NETWORKS / DUOMENŲ PERDAVIMO SPARTOS TYRIMAS JUDRIOJO RYŠIO TINKLUOSE
Authors: Žvinys Karolis
Published: October 2013

This work analyses communication channel settings of UMTS technology, which are related with a data transfer throughput. The paper describes the measurement equipment that is suitable for measuring parameters of a mobile network channel. Besides, it analyses the suitability of this equipment and issue of parameter values that are associated with data throughput. Further, the study includes the selection of the most specific parameters, which are crucial for data speed. Using these parameters, models were developed for prediction of data transfer throughput. To build the model, the linear and nonlinear forecasting methods were used. The linear prediction was made by using linear regression, nonlinear — neural networks. Using the linear prediction model, 77.83% forecast accuracy was achieved, while the accuracy of forecasted nonlinear transmission rate amounted to 76.19%. The accuracy of prediction models was obtained using eight parameters of the communication channel. Finally, the paper presents the data throughput prediction models that allow predicting data speed with the help of channel parameters presented by a standard terminal. The list of these channel parameters is derived from five UE‘s of different manufacturers. The expected most accurate data transfer rate can be predicted using a set of parameters issued by Nokia device.

Article in Lithuanian.

Santrauka

Darbe nagrinėjami su duomenų perdavimo sparta susiję UMTS technologijos ryšio kanalo parametrai. Analizuojama mobiliojo tinklo kanalo parametrų matavimo įranga, jos galimybės ir tinkamumas. Tyrimai apima konkrečių su duomenų pralaidumu sąveikaujančių parametrų išskyrimą. Remiantis šiais parametrais darbe kuriami duomenų perdavimo spartos prognozavimo modeliai. Tiesinės prognozės atveju pasiektas 77,83 %, o netiesinės prognozės – 76,19 % tikėtinos duomenų perdavimo spartos prognozės tikslumas. Atsižvelgiant į vartotojų interesus, siūlomi jų įrangų prognozės modeliai. Nagrinėjama pagrindinių pasaulio gamintojų kuriama galinė vartotojų įranga. Remiantis šios įrangos parametrais, pateikiami prognozės modeliai. Tiksliausiai duomenų perdavimo sparta gali būti prognozuojama naudojant „Nokia“ gamintojo įrenginių parametrų rinkinį.
INVESTIGATION OF THE CONCENTRATED DOUBLE LAYER SIX-PHASE WINDING / SUTELKTOSIOS DVISLUOKSNĖS ŠEŠIAFAZĖS APVIJOS SUDARYMAS
Authors: Kundrotas Benas
Published: October 2013

The article discusses advantages of multiphase motors against three phase motors. It considers the areas of application of multiphase induction motors. The author proposes concentrated double layer short pitch coil winding connection. The research indicated that according to the first harmonic, the short pitch coil winding has greater efficiency than a full pitch coil. Article in Lithuanian. Santrauka Straipsnyje apžvelgti daugiafazių variklių pranašumai, palyginti su trifaziais varikliais. Nurodytos pagrindinės daugiafazių variklių naudojimo sritys. Sudaryta sutelktosios dvisluoksnės sutrumpinto žingsnio šešiafazės apvijos sekcijų jungimo schema, elektrinių schemų išklotinė ir gautas šios apvijos sukamosios magnetovaros pasiskirstymas erdvėje.
SMART INDUCTION DRIVE / IŠMANIOJI ASINCHRONINĖ PAVARA
Authors: Uznys Donatas
Published: October 2013

The article focuses on the induction drive with a fuzzy controller. This controller adopts direct torque control. It aims to halve pulsations of electromagnetic torque and stator current. The author introduces the basics of direct torque control as well as principles of fuzzy controller development and computer model of smart induction drive. Simulation results were compared to results of traditional direct torque control computer model. The use of fuzzy controller achieved two-times lower pulsations of torque, stator current and flux, plus lowered maximum overshoots.

Article in Lithuanian.

Santrauka

Nagrinėjama neraiškiuoju reguliatoriumi valdoma asinchroninė pavara. Reguliatorius įgyvendina tiesioginį momento valdymą. Pagrindinis jo tikslas – sumažinti elektromagnetinio momento ir statoriaus srovės švytavimus. Aprašomi tiesioginio momento valdymo pagrindai. Pateikti neraiškiojo reguliatoriaus sudarymo principai ir išmaniosios pavaros kompiuterinis modelis. Gauti imitacijos rezultatai lyginami su klasikinio tiesioginio momento valdymo kompiuterinio modelio rezultatais. Neraiškiojo reguliatoriaus naudojimas leidžia gauti perpus mažesnius momento, statoriaus srovės ir srauto švytavimus, mažesnes didžiausias dinamines nuokrypas.
THE FREQUENCY CHARACTERISTICS OF COUPLED MICROSTRIP LINES / SUSIETŲJŲ MIKROJUOSTELINIŲ LINIJŲ DAŽNINĖS CHARAKTERISTIKOS
Authors: Krukonis Audrius , Mikučionis Šarūnas
Published: October 2013

The article deals with the use of the finite difference time domain method and uniaxial perfectly matching layer for analysis of frequency characteristics of coupled microstrip transmission lines. It describes calculation techniques for voltage, current, characteristic impedance and effective dielectric constant of each signal conductor. Besides, it analyses the frequency dependencies of characteristic impedance and the effective dielectric constant. Article in Lithuanian. Santrauka Straipsnyje aptariamas baigtinių skirtumų laiko srities metodo taikymas ir absorbuojančio sluoksnio taikymas susietųjų mikrojuostelinių linijų analizei. Sudaryti ir išnagrinėti baigtinių skirtumų laiko srities metodu grįsti susietųjų mikrojuostelinių linijų matematiniai modeliai. Pateikiamos kiekvieno iš laidininkų įtampos, srovės, charakteringojo impedanso ir efektyviosios dielektrinės skvarbos skaičiavimo metodikos. Aptariami skaičiavimo metodikų pranašumai, trūkumai, pateikiamos jų tobulinimo kryptys.
EFFECT OF PLATELET-RICH PLASMA MIXED WITH A POLYMERIC BONE FILLING MATERIAL ON SINUS FLOOR AUGMENTATION IN RABBITS
Authors: Tseng Ching-Li , Hsu Po-Chih , Wei Lin-Gwei , Wu Te-Hsing , Shen Li-Han , Chang Guang-Wei , Fang Hsu-Wei , Tsai Jui-Che , Shen Yi-Ching , Wu Chi-Chang , Chen Tim-Mo
Published: October 2013

Sinus augmentation is a common approach for patients with severe alveolar ridge atrophy but an ideal material to increase the bone volume for dental implantation is still needed. The present study evaluated the effect of a newly developed polymeric bone-filling powder (formed from acrylic acid and N-isopropylacrylamide, ANa) mixed with platelet-rich plasma (PRP) for bone generation in a rabbit model of sinus augmentation. A total of 12 New Zealand White rabbits were randomly divided into three groups based on filling material. All animals underwent a bilateral maxillary sinus augmentation. PRP was prepared using an automatic separation system to obtain a high platelet concentration. ANa powder was individually mixed with phosphate-buffered saline (PBS) or PRP for sinus floor elevation. The left maxillary sinus received the ANa/PBS filling, whereas the right maxillary sinus received a mixture of ANa/PRP gel. Equal volumes of filling material were inserted in each maxillary sinus. Thus, defects with no implantation served as controls. Animals were sacrificed at 4 and 12 weeks, and then all specimens were harvested for micro-computed tomography (micro-CT) and histological analysis. On micro-CT evaluation, ANa/PRP significantly increased the bone volume in maxillary sinus augmentation relative to the negative control and ANa/PBS after 12 weeks. New bone areas with osteocytes and osteon formation were found in all three groups at 12 weeks post-implantation. This study confirms that ANa mixed with PRP can effectively increase the bone volume in the sinus cavity. This benefit for sinus augmentation may increase the success of dental implantation because of the formation of a thin layer of alveolar bone.
RADIOLOGICAL ASSESSMENTS OF INJECTED CALCIUM SULFATE BONE CEMENTS IN THE TREATMENT OF DISTAL RADIAL FRACTURE
Authors: Hsu Li-Ho , Chiang Chih-Yung , Yang Kai-Chiang , Wu Chang-Chin
Published: October 2013

It has been reported in many literatures that different kinds of bone graft augmentations have been applied in the treatment of distal radial fractures with favorable results. The authors applied calcium sulfate cement in the treatment of distal radial fractures and evaluated the radiological outcomes of 33 patients. The radiological changes of cement statuses, implants, and radiological parameter of distal radius were analyzed. After closed reduction of the displacement, fractures were fixed by Kirschner pins and stabilized by percutaneous injection of premixed calcium sulfate bone cement. Periodic X-ray evaluations were obtained at immediate post-operation and at every month. A total of 28 patients completed the follow-up and the cement extravasations into wrist joint or into soft tissues had been seen in almost every patient. The gradual settling and losses of radial height, radial inclination angle, and volar tilting angles were significant even after removal of Kirschner pins after 8 weeks. Gradual absorptions of cured cement block inside and outside distal radial cortices were observed in every case and complete absorptions of intraosseous cements after 8 weeks happened in 53.6% (15/28) of patients. The extravasated cements took longer time to fade away. The radiological results of current study revealed negative results of calcium sulfate applied in the treatment of distal radial fracture in terms of reduction parameters and cement block longevity.
A Highest Sense Count Based Method for Disambiguation of Web Queries for Hindi Language Web Information Retrieval
Authors: Dwivedi Sanjay K.
Published: October 2013

The ambiguity in word senses has been recognized as a major challenge for the information retrieval systems. Hindi language web information retrieval, like other languages, faces the problem of sense ambiguity. The sense ambiguity problem deteriorates the performance of every natural language processing (NLP) application. The performance of Hindi language web information retrieval is also affected by it. In this paper, the author formalized an approach for the disambiguation of the senses to improve the performance of Hindi web information retrieval. Our system works in such a way that ambiguity detection has been performed before disambiguation of web queries. Test samples of 100 queries have been selected. When these queries were subjected to ambiguity detection, we found that 43% of them have been detected unambiguous. After ambiguity detection, the disambiguation approach is followed which is based on HSC (Highest Sense Count). Query disambiguation approach further follows query expansion. The expanded query generates the new result set which results into high precision and high similarity score. The 57 expanded queries are tested against 1000 test document instances. The overall improvement is 45% in the average precision, 23% in interpolated average precision and a significant improvement in the average similarity score of the new generated result set. The overall accuracy of our approach has been 61.4% and it improves the performance of the system by 45%.
Chronological Ordering Based on Context Overlap Detection
Authors: Haggag Mohamed H. , Othman Bassma M.
Published: October 2013

Context processing plays an important role in different Natural Language Processing applications. Sentence ordering is one of critical tasks in text generation. Following the same order of sentences in the row sources of text is not necessarily to be applied for the resulted text. Accordingly, a need for chronological sentence ordering is of high importance in this regard. Some researches followed linguistic syntactic analysis and others used statistical approaches. This paper proposes a new model for sentence ordering based on sematic analysis. Word level semantics forms a seed to sentence level sematic relations. The model introduces a clustering technique based on sentences senses relatedness. Following to this, sentences are chronologically ordered through two main steps; overlap detection and chronological cause-effect rules. Overlap detection drills down into each cluster to step through its sentences in chronological sequence. Cause-effect rules forms the linguistic knowledge controlling sentences relations. Evaluation of the proposed algorithm showed the capability of the proposed model to process size free texts, non-domain specific and open to extend the cause-effect rules for specific ordering needs.
A dynamic plant chamber system with downstream reaction chamber to study the effects of pollution on biogenic emissions
Authors: Timkovsky J. , Gankema P. , Pierik R. , Holzinger R.
Published: October 2013

Abstract. A system of two dynamic plant chambers and a downstream reaction chamber has been set up to investigate the emission of biogenic volatile organic compounds (BVOC) and possible effects from pollutants such as ozone. The system can be used to compare BVOC emissions from two sets of differently treated plants, or to study the photochemistry of real plant emissions under polluted conditions without exposing the plants to pollutants. The main analytical tool is a proton-transfer-reaction time-of-flight mass spectrometer (PTR-TOF-MS) which allows online monitoring of biogenic emissions and chemical degradation products. The identification of BVOCs and their oxidation products is aided by cryogenic trapping and subsequent in situ gas chromatographic analysis. The data presented in the paper demonstrates the good performance of the setup.
Estimates of aerosol absorption over India using multi-satellite retrieval
Authors: Narasimhan D. , Satheesh S. K.
Published: October 2013

Abstract. Aerosol absorption is poorly quantified because of the lack of adequate measurements. It has been shown that the Ozone Monitoring Instrument (OMI) aboard EOS-Aura and the Moderate Resolution Imaging Spectroradiometer (MODIS) aboard EOS-Aqua, which fly in formation as part of the A-train, provide an excellent opportunity to improve the accuracy of aerosol retrievals. Here, we follow a multi-satellite approach to estimate the regional distribution of aerosol absorption over continental India for the first time. Annually and regionally averaged aerosol single-scattering albedo over the Indian landmass is estimated as 0.94 ± 0.03. Our study demonstrates the potential of multi-satellite data analysis to improve the accuracy of retrieval of aerosol absorption over land.
Identifying Tribal Rights That Could Affect a Water Utility
Authors: Baker Keri‐Ann C.
Published: October 2013

Native American tribes are independent, sovereign nations with water and traditional treaty rights that are often deemed superior to a water utility's rights. Several courts in the United States have determined tribal status to be higher than that of a state. This sovereignty status provides tribes with unique rights, particularly concerning the allocation of water.
A Multi-Institutional Study of High School Mathematics Curricula and College Mathematics Achievement and Course Taking
Authors: Harwell Michael R. , Post Thomas R. , Medhanie Amanuel , Dupuis Danielle N. , LeBeau Brandon
Published: October 2013

This study examined the relationship between high school mathematics curricula and student achievement and course-taking patterns over 4 years of college. Three types of curricula were studied: National Science Foundation (NSF)-funded curricula, the University of Chicago School Mathematics Project curriculum, and commercially developed curricula. The major result was that high school mathematics curricula were unrelated to college mathematics achievement or students' course-taking patterns for students who began college with precalculus (college algebra) or a more difficult course. However, students of the NSF-funded curricula were statistically more likely to begin their college mathematics at the developmental level.
Environmental and Economic Benefits of Slow Steaming
Authors: Zanne Marina , Počuča Milojka , Bajec Patricija
Published: October 2013

Notwithstanding the fact that maritime shipping is the most energy efficient mode of transportation for large quantities of freight, there are continues efforts to improve its performance. These efforts have become even more intensive since the beginning of global economic crisis. Slow steaming is one of the attempts to improve both environmental and economic performance of maritime shipping. The paper gives an overview of existing studies on slow steaming and lists other available and already applicable solutions.
DNA Interstrand Cross‐Link Formation Using Furan as a Masked Reactive Aldehyde
Authors: Carrette Lieselot L.G. , Gyssels Ellen , Madder Annemieke
Published: October 2013

This unit describes a method for interstrand cross‐linking between a furan‐modified oligonucleotide and its unmodified complement. The synthesis of two furan‐modified phosphoramidites, selected based on high cross‐linking yield versus improved cross‐linking selectivity, is described. The methods allow gram‐scale synthesis starting from stable and readily available furan derivatives. Cross‐linking requires selective oxidation of the furan moiety to an aldehyde. The masked nature of the latter avoids undesired and off‐target reactions, resulting in clean and high‐yield cross‐link formation. Curr. Protoc. Nucleic Acid Chem. 54:5.12.1‐5.12.16. © 2013 by John Wiley & Sons, Inc.