bluuebunny/crossref_metadata_2025 huggingface dataset:
Using hydrologic measurements to investigate free-phase gas ebullition in a Maine peatland, USA
Authors: Bon C. E. , Reeve A. S. , Slater L. , Comas X.
Published: March 2014

Abstract. Northern peatlands cover more than 350 million ha and are an important source of methane (CH4) and other biogenic gases contributing to climate change. Free-phase gas (FPG) accumulation and episodic release has recently been recognized as an important mechanism for biogenic gas flux from peatlands. It is likely that gas production and groundwater flow are interconnected in peatlands: groundwater flow influences gas production by regulating geochemical conditions and nutrient supply available for methanogenesis, while FPG influences groundwater flow through a reduction in peat permeability and by creating excess pore water pressures. Water samples collected from three well sites at Caribou Bog, Maine, show substantial dissolved CH4 (5–16 mg L−1) in peat waters below 2 m depth and an increase in concentrations with depth. This suggests production and storage of CH4 in deep peat that may be episodically released as FPG. Two min increment pressure transducer data reveal approximately 5 cm fluctuations in hydraulic head from both deep and shallow peat that are believed to be indicative of FPG release. FPG release persists up to 24 h during decreasing atmospheric pressure and a rising water table. Preferential flow is seen towards an area of relatively lower hydraulic head associated with the esker and pool system. Increased CH4 concentrations are also found at the depth of the esker crest, suggesting that the high permeability esker is acting as a conduit for groundwater flow, driving a downward transport of labile carbon, resulting in higher rates of CH4 production.
Antecedent flow conditions and nitrate concentrations in the Mississippi River basin
Authors: Murphy J. C. , Hirsch R. M. , Sprague L. A.
Published: March 2014

Abstract. The relationship between antecedent flow conditions and nitrate concentrations was explored at eight sites in the 2.9 million square kilometers (km2) Mississippi River basin, USA. Antecedent flow conditions were quantified as the ratio between the mean daily flow of the previous year and the mean daily flow from the period of record (Qratio), and the Qratio was statistically related to nitrate anomalies (the unexplained variability in nitrate concentration after filtering out season, long-term trend, and contemporaneous flow effects) at each site. Nitrate anomaly and Qratio were negatively related at three of the four major tributary sites and upstream in the Mississippi River, indicating that when mean daily streamflow during the previous year was lower than average, nitrate concentrations were higher than expected. The strength of these relationships increased when data were subdivided by contemporaneous flow conditions. Five of the eight sites had significant negative relationships (p ≤ 0.05) at high or moderately high contemporaneous flows, suggesting nitrate that accumulates in these basins during a drought is flushed during subsequent high flows. At half of the sites, when mean daily flow during the previous year was 50 percent lower than average, nitrate concentration can be from 9 to 27 percent higher than nitrate concentrations that follow a year with average mean daily flow. Conversely, nitrate concentration can be from 8 to 21 percent lower than expected when flow during the previous year was 50 percent higher than average. Previously documented for small, relatively homogenous basins, our results suggest that relationships between antecedent flows and nitrate concentrations are also observable at a regional scale. Relationships were not observed (using all contemporaneous flow data together) for basins larger than 1 million km2, suggesting that above this limit the overall size and diversity within these basins may necessitate the use of more complicated statistical approaches or that there may be no discernible basin-wide relationship with antecedent flow. The relationships between nitrate concentration and Qratio identified in this study serve as the basis for future studies that can better define specific hydrologic processes occurring during and after a drought (or high flow period) which influence nitrate concentration, such as the duration or magnitude of low flows, and the timing of low and high flows.
Satellite radar altimetry for monitoring small river and lakes in Indonesia
Authors: Sulistioadi Y. B. , Tseng K.-H. , Shum C. K. , Hidayat H. , Sumaryono M. , Suhardiman A. , Setiawan F. , Sunarso S.
Published: March 2014

Abstract. Remote sensing and satellite geodetic observations are capable for hydrologic monitoring of freshwater resources. For the case of satellite radar altimetry, limited temporal resolutions (e.g., satellite revisit period) prohibit the use of this method for a short (< weekly) interval monitoring of water level or discharge. On the other hand, the current satellite radar altimeter footprints limit the water level measurement for rivers wider than 1 km. Some studies indeed reported successful retrieval of water level for small-size rivers as narrow as 80 m; however, the processing of current satellite altimetry signals for small water bodies to retrieve accurate water levels, remains challenging. To address this scientific challenge, this study tries to monitor small (40–200 m width) and medium-sized (200–800 m width) rivers and lakes using satellite altimetry through identification and choice of the over-water radar waveforms corresponding to the appropriately waveform-retracked water level. This study addresses the humid tropics of Southeast Asia, specifically in Indonesia, where similar studies do not yet exist and makes use Level 2 radar altimeter measurements generated by European Space Agency's (ESA's) Envisat (Environmental Satellite) mission. This experiment proves that satellite altimetry provides a good alternative, or the only means in some regions, to measure the water level of medium-sized river (200–800 m width) and small lake (extent < 1000 km2) in Southeast Asia humid tropic with reasonable accuracy. In addition, the procedure to choose retracked Envisat altimetry water level heights via identification or selection of standard waveform shapes for inland water is recommended and should be a standard measure especially over small rivers and lakes. This study also found that Ice-1 is not necessarily the best retracker as reported by previous studies, among the four standard waveform retracking algorithms for Envisat radar altimetry observing inland water bodies.
Landslide and slope stability evaluation in the historical town of Kruja, Albania
Authors: Muceku Y. , Korini O.
Published: March 2014

Abstract. This paper describes landslides and slope stability evaluation in the urban area of Kruja, Albania. Kruja is a historical and heritage center, due to the existence of many important cultural monuments, including "Skanderbeg" castle and Bazaar square, etc. The urban area of Kruja has been affected by landslide effects, in the past and also the present. From this phenomenon many engineering objects such as buildings, roads, etc., are damaged and demolished. From engineering geological mapping at scale 1:5000 it is observed that many active landslides have dramatically increased in activity since the 1980s. The landslide types found in the studied area are earthslides, debris flow, as well as rockfall and rock rolling. Also, from field works and laboratory analysis, the slope stability of the whole urban area has been determined; for this purpose the studied zone is divided into stable and unstable areas, which helps to better understand mass movement activity as one of the most harmful hazards of geodynamic phenomena.
Rainstorms able to induce flash floods in a Mediterranean-climate region (Calabria, southern Italy)
Authors: Terranova O. G. , Gariano S. L.
Published: March 2014

Abstract. Heavy rainstorms often induce flash flooding, one of the natural disasters most responsible for damage to man-made infrastructure and loss of lives, adversely affecting also the opportunities for socio-economic development of Mediterranean Countries. The frequently dramatic damage of flash floods are often detected with sufficient accuracy by post-event surveys, but rainfall causing them are still only roughly characterized. With the aim of improving the understanding of the temporal structure and spatial distribution of heavy rainstorms in the Mediterranean context, a statistical analysis was carried out in Calabria (southern Italy) concerning rainstorms that mainly induced flash floods, but also shallow landslides and debris-flows. Thus a method is proposed – based on the overcoming of heuristically predetermined threshold values of cumulated rainfall, maximum intensity, and kinetic energy of the rainfall event – to select and characterize the rainstorms able to induce flash floods in the Mediterranean-climate Countries. Therefore the obtained (heavy) rainstorms were automatically classified and studied according to their structure in time, localization and extension. Rainfall-runoff watershed models can consequently benefit from the enhanced identification of design storms, with a realistic time structure integrated with the results of the spatial analysis. A survey of flash flood events recorded in the last decades provides a preliminary validation of the method proposed to identify the heavy rainstorms and synthetically describe their characteristics. The notable size of the employed sample, including data with a very detailed resolution in time, that relate to several rain gauges well-distributed throughout the region, give robustness to the obtained results.
New insights on the occurrence of peperites and sedimentary deposits within the silicic volcanic sequences of the Paraná Magmatic Province, Brazil
Authors: Luchetti A. C. F. , Nardy A. J. R. , Machado F. B. , Madeira J. E. O. , Arnosio J. M.
Published: March 2014

Abstract. The PMP (Paraná Magmatic Province) is characterized by lava flows of the Early Cretaceous Serra Geral Formation which covers about 75% of the Paraná Basin (southern and southeastern Brazil), composed of a thick (up to 1600 m) volcanic sequence formed by a succession of petrographically and geochemically distinct units of basic and silicic composition. The whole package must have been emplaced during approximately 3 million years of nearly uninterrupted activity. A few aeolian sandstone layers, indicating arid environmental conditions (the Botucatu Formation), are interlayered in the lower basalts. Above the basalts, the Palmas and Chapecó Members are composed of silicic volcanic rocks (quartz latites, dacites, rhyodacites and rhyolites) and basalts. This paper presents new evidence of sedimentation episodes separating silicic volcanic events, expressed by the occurrence of sedimentary deposits. Interaction between the volcanic bodies and the coeval unconsolidated sediments formed peperites. The sediments were observed between basaltic lava flows and silicic rocks or interlayered in the Palmas-type rocks, between the Chapecó-type rocks and overlying basaltic flows, between silicic bodies of the Palmas and Chapecó types, and interlayered within Palmas-type units. The observed structures indicate that the sediments were still wet and unconsolidated, or weakly consolidated, at the time of volcanism, which, coupled with the sediment features, reflect environmental conditions that are different from those characterizing the Botucatu arid conditions.
Physicochemical changes in pyrogenic organic matter (biochar) after 15 months field-aging
Authors: Mukherjee A. , Zimmerman A. R. , Hamdan R. , Cooper W. T.
Published: March 2014

Abstract. Predicting the effects of pyrogenic organic matter (OM) addition (either natural or intentional as in the case of biochar amendment) on soil chemistry and crop yields has been hampered by a lack of understanding of how pyrogenic OM evolves in the environment over time. This work compared the physicochemical characteristics of newly-made and 15 month field-aged biochars and biochar-soil mixtures. After aging, biochars made by pyrolysis of wood and grass at 250, 400 and 650 °C exhibited 5-fold increases in cation exchange capacity (CEC), on average, appearance of anion exchange capacity (AEC) and significant decreases in pH, ash content and nanopore surface area. Cross polarization 13C-NMR analyses indicated relative increases in O-containing functional groups including substituted aryl, carboxyl and carbonyl C, likely via abiotic and microbial oxidation and losses of O-alkyl groups, likely via leaching. Similar chemical trends were observed for soil-biochar mixtures suggesting the same biochar aging processes occurred in the soil environment. However, there was evidence for a major role of soil OM-microbe-biochar interaction during aging. Field-aging of soil with biochar resulted in large increases in C and N content (up to 124 and 143%, respectively) and exchange capacity (up to 43%) beyond that calculated by the weighted addition of the properties of biochar and soil aged separately. These beneficial interactive effects varied greatly with soil and biochar type. Scanning electronic microscopy (SEM) images of biochar particles, both aged alone and with soil, showed colonization by microbes and widespread surficial deposits that were likely OM. Thus, sorption of both microbially-produced and soil OM are likely processes that enhanced biochar aging. Among the important implications of these findings are that biochar's full beneficial effects on soil properties only occur over time and proper assignment of C sequestration credits to biochar users will require consideration of soil-biochar interactions.
Isolated hyperphosphatemia as an early manifestation in asymptomatic multiple myeloma
Authors: Gupta Monica , Singh Pritam
Published: March 2014

Usual presentation of multiple myeloma with symptoms like bone pains, renal failure or recurrent infections do not pose much of a diagnostic challenge, but difficulties arise when symptoms are vague and spurious results of laboratory investigations complicate the clinical picture. Hyperphosphatemia is usually observed in cases that have high disease burden (tumor lysis syndrome) or impaired renal functions; however its occurrence with solitary plasmacytoma or early stages (low burden) with preserved renal functions is unlikely and probably best explicable on account of pseudohyperphosphatemia- a laboratory error that results from interference in colorimetric estimation of serum phosphate because of existence of paraproteins in these patients. We, hereby, report a case where evaluation of asymptomatic hyperphosphatemia led to the final diagnosis of multiple myeloma.
A Dimeric Copper(II) Complex of Oxalate and Oxamide Dioxime Ligands: Synthesis, Crystal Structure, Thermal Stability, and Magnetic Properties
Authors: Nenwa Justin , Djonwouo Patrick L. , Nfor Emmanuel N. , Bélombé Michel M. , Jeanneau Erwann , Mbarki Mohammed , Fokwa Boniface P. T.
Published: March 2014

The dimeric copper(II) complex [Cu(C2O4)(H2oxado)(H2O)]2 (1), where H2oxado=oxamide dioxime, has been synthesized in water and characterized by elemental and thermal analyses, IR spectroscopy, and single-crystal X-ray diffraction. Complex 1 is composed of two neutral [Cu(C2O4)(H2oxado)(H2O)] entities connected by Cu-O bonds between oxalate oxygen atoms and copper(II) ions, thereby producing a centrosymmetric dimer, with the Cu(II) centers exhibiting a strongly distorted octahedral coordination. Neighboring dimers are hydrogen-bonded through O- H···O interactions leading overall to a layer structure. Thermal analyses of complex 1 showed two significant weight losses corresponding to the coordinated water molecules, followed by the decomposition of the network. Variable-temperature (10 - 300 K) magnetic susceptibility measurements revealed very weak antiferromagnetic interactions (θ = 0:86 K from Curie-Weiss law behavior) within the dinuclear unit
The Path Planning of AUV Based on D-S Information Fusion Map Building and Bio-Inspired Neural Network in Unknown Dynamic Environment
Authors: Zhu Daqi , Li Weichong , Yan Mingzhong , Yang Simon X.
Published: March 2014

In this paper a biologically inspired neural dynamics and map planning based approach are simultaneously proposed for AUV (Autonomous Underwater Vehicle) path planning and obstacle avoidance in an unknown dynamic environment. Firstly the readings of an ultrasonic sensor are fused into the map using the D-S (Dempster-Shafer) inference rule and a two-dimensional occupancy grid map is built. Secondly the dynamics of each neuron in the topologically organized neural network is characterized by a shunting equation. The AUV path is autonomously generated from the dynamic activity landscape of the neural network and previous AUV location. Finally, simulation results show high quality path optimization and obstacle avoidance behaviour for the AUV.
Variable Structure Control for Space Robots Based on Neural Networks
Authors: Fang Yaming , Zhang Wenhui , Ye Xiaoping
Published: March 2014

Problems of trajectory tracking for a class of free-floating robot manipulators with uncertainties are considered. Two neural network controls are designed. The first scheme consists of a PD feedback and a dynamic compensator which is an RBF neural network controller. The second scheme syncretizes neural networks with variable structures using a saturation function. Neutral networks are used to adaptively learn about and compensate for the unknown system. Approach errors are eliminated as disturbances by using the variable structure controller. The shortcomings of local networks are considered. The control is based on dividing aspects into three sections with classification and integration: state dimensional, neural network and variable structure separate control. When invalidations of the neutral network appeared, the controller was able to guarantee good robustness as well as the stability of the closed-loop system. The simulation results show that the methods presented are effective.
Depth Control for Micro-Autonomous Underwater Vehicles (μAUVs): Simulation and Experimentation
Authors: Watson Simon A. , Green Peter N.
Published: March 2014

Swarms of micro-autonomous underwater vehicles (μAUVs) are an attractive solution to the problem of nuclear storage pond monitoring. Independent movement in the horizontal and vertical planes is necessary to maximize manoeuvrability. This paper presents a comparison of different control strategies for independent depth control using both simulations and real experimental results. PID, sliding mode and a simplification of sliding mode (called ‘bounded PD’) are simulated using a MATLAB/SIMULINK model and are then compared to experimental results obtained when the controllers were implemented on a prototype μAUV.
A Hierarchical Fuzzy Control Design for Indoor Mobile Robot
Authors: Abdessemed Foudil , Faisal Mohammed , Emmadeddine Muhammed , Hedjar Ramdane , Al-Mutib Khalid , Alsulaiman Mansour , Mathkour Hassan
Published: March 2014

This paper presents a motion control for an autonomous robot navigation using fuzzy logic motion control and stereo vision based path-planning module. This requires the capability to maneuver in a complex unknown environment. The mobile robot uses intuitive fuzzy rules and is expected to reach a specific target or follow a prespecified trajectory while moving among unforeseen obstacles. The robot's mission depends on the choice of the task. In this paper, behavioral-based control architecture is adopted, and each local navigational task is analyzed in terms of primitive behaviors. Our approach is systematic and original in the sense that some of the fuzzy rules are not triggered in face of critical situations for which the stereo vision camera can intervene to unblock the mobile robot.
Tuning a PD Controller Based on an SVR for the Control of a Biped Robot Subject to External Forces and Slope Variation
Authors: Ferreira João P. , Crisóstomo Manuel , Coimbra A. Paulo
Published: March 2014

Real-time balance control of an eight-link biped robot using a zero moment point (ZMP) dynamic model is difficult to achieve due to the processing time of the corresponding equations. To overcome this limitation an intelligent computing technique based on Support Vector Regression (SVR) is developed and presented in this paper. To implement a PD controller the SVR uses the ZMP error relative to a reference and its variation as inputs, and the output is the correction of the angle of the robot's torso, necessary for its sagittal balance. The SVR was trained based on simulation data generated using a PD controller. The initial values of the parameters of the PD controller were obtained by the second Ziegler-Nichols method. In order to evaluate the balance performance of the biped robot, three performance indexes are used.

The ZMP is calculated by reading four force sensors placed under each of the robot's feet. The gait implemented in this biped is similar to a human gait, which is acquired and adapted to the robot's size.

The main contribution of this paper is the fine-tuning of the ZMP controller based on the SVR. To implement and test this, the biped robot was subjected to external forces and slope variation. Some experiments are presented and the results show that the implemented gait combined with the correct tuning of the SVR controller is appropriate for use with this biped robot. The SVR controller runs at 0.2 ms, which is about 50 times faster than a corresponding first-order TSK neural-fuzzy network.
2D-3D Face Recognition Method Basedon a Modified CCA-PCA Algorithm
Authors: Kamencay Patrik , Hudec Robert , Benco Miroslav , Zachariasova Martina
Published: March 2014

This paper presents a proposed methodology for face recognition based on an information theory approach to coding and decoding face images. In this paper, we propose a 2D-3D face-matching method based on a principal component analysis (PCA) algorithm using canonical correlation analysis (CCA) to learn the mapping between a 2D face image and 3D face data. This method makes it possible to match a 2D face image with enrolled 3D face data. Our proposed fusion algorithm is based on the PCA method, which is applied to extract base features. PCA feature-level fusion requires the extraction of different features from the source data before features are merged together. Experimental results on the TEXAS face image database have shown that the classification and recognition results based on the modified CCA-PCA method are superior to those based on the CCA method. Testing the 2D-3D face match results gave a recognition rate for the CCA method of a quite poor 55% while the modified CCA method based on PCA-level fusion achieved a very good recognition score of 85%.
Impacts of climate change on runoff in the Yellow River, China
Authors: Lyu Jiqiang , Zezhong Zhang , Shen Bing
Published: March 2014

This research investigated the temporal variability of water resources and the response of water resources to seasonal frozen soil, snow cover, and climate elements for the high, cold area at the headwaters of the upper Yellow River in western China. Data analyzed were a 49‐year monthly data series of runoff, temperature, and precipitation collected from 1959 to 2007; snow‐cover monitoring data collected from 2000 to 2011; and permafrost monitoring data from two control hydrometrical stations and one weather station. Study methods were the peak pattern analytical method, the rate change of wetness–dryness analytical method, the Mann‐Kendall Trend Test, and grey relational analysis. The Mann‐Kendall test was used to identify trends and change points in the annual runoff series. The results show obvious historical characteristics for river runoff, with the change points in years 1961, 1999, and 2005, and find that the runoff series showed a declining tendency from 2002 to 2006. After 1986, the maximum seasonal frozen soil depth declined, which exacerbated the total annual runoff reduction. The annual decrease in temperature since 2005 and the decrease in annual snow‐cover area and precipitation in 2009 and 2010 caused water scarcity in 2011 and may cause water scarcity in the subsequent two to five years, according to the historical characteristics of Yellow River runoff.
New Economic Geography and the Conception of Social Factors of Criminality: Areas of Common Interest and Prospects for Synthesis
Authors: Bakharev Dmitry V.
Published: March 2014

The article discusses the application of «new economic geography» in investigating the reasons for territorial distinctions and other factors of criminality.
Large increase in refractive index inside silica glass after the movement of voids caused by femtosecond laser pulses
Authors: Hashimoto Fumiya , Yoshino Tomoki , Ozeki Yasuyuki , Itoh Kazuyoshi
Published: March 2014

When a transparent material is irradiated by focused femtosecond laser pulses, various types of structural modification can occur inside the material. Recently, it has been reported that asymmetric structures, which are composed of two regions with positive and negative refractive index changes (Δn), can be inscribed by irradiation of multiple femtosecond laser pulses at high (∼MHz) repetition rates. Interestingly, the amount of positive Δn in this type of modification is larger than those in conventional structural modifications by one order of magnitude. However, the mechanisms underlying such modifications are still unclear. In this paper, we describe that similar asymmetric structures can be inscribed by using femtosecond laser pulses at a low repetition rate. Then, we examine the formation and spectroscopic characteristics of the asymmetric structures. The observation of the processed areas reveals that the asymmetric structures are formed after the movement of voids. Furthermore, micro-Raman spectroscopy suggests a large increase of three-membered ring structures in the region with positive Δn, which may account for the large Δn.
Comparison between theoretical and experimental results for energy states of two-dimensional electron gas in pseudomorphically strained InAs high-electron-mobility transistors
Authors: Nishio Yui , Tange Takahiro , Hirayama Naomi , Iida Tsutomu , Takanashi Yoshifumi
Published: March 2014

The energy states of a two-dimensional electron gas (2DEG) in high-electron-mobility transistors with a pseudomorphically strained InAs channel (PHEMTs) were analyzed rigorously using a recently established theory that takes into account the nonparabolicity of the conduction band of the channel layer. The sheet density of the 2DEG in In
x
Ga1−

x
As-PHEMTs and the drain I–V characteristics of those devices were calculated theoretically and compared with the density and characteristics obtained experimentally. Not only the calculated threshold voltage (V
TH) but also the calculated transconductance agreed fairly well with the corresponding values obtained experimentally. When the effects of the compositions of the In
x
Ga1−

x
As subchannel layer in the composite channel and the channel layer on energy states of 2DEG were investigated in order to establish a guiding principle for a design of the channel structure in PHEMTs, it was found that V
TH is determined by the effective conduction-band offset energy ΔE
C between the InAlAs barrier and the channel layers.
Low-propagation-loss Ta2O5 optical waveguides on silica substrate
Authors: Li Gen , Maruyama Takeo , Iiyama Koichi
Published: March 2014

In this paper, a high-refractive-index (∼2.0) and low-propagation-loss tantalum pentoxide (Ta2O5) waveguide is reported. We fabricated Ta2O5 strip optical waveguides with a cross section of 400 nm × 10 µm by chemical solution deposition (CSD) followed by CF4 reactive ion etching. The optimum fabrication steps make it possible to obtain the Ta2O5 strip optical waveguides with a propagation loss of less than 1 dB/cm at 830 nm, which is significant for optoelectronic integrated circuits in the 0.8 µm wavelength range.
New Linearity Error Correction Technology for A/D and D/A Converter LSI
Authors: Akazawa Y. , Matsuya Y. , Iwata A.
Published: March 2014

To realize a high precision monolithic A/D and D/A converter, new error correction technology labeled LEGS (Linearity Error Correction by Digital Code Shift) that utilizes fully digital processing and a two stage weighted capacitor array is proposed. This technology has the advantage that it provides a significant reduction in required tolerance for weighting network components as well as a number of highly precise analog circuits. This paper describes the basic correction approach, its effectiveness, and a 14-bit accuracy A/D and D/A converter configuration based on this correction technology.
Very Wide-Band Silicon Bipolar Monolithic Amplifiers
Authors: Ohara Mamoru , Kamoto Tsutomu , Sakai Tetsushi
Published: March 2014

We have developed very wide-band monolithic amplifiers, using an advanced silicon bipolar process called SST-2 which made it possible to lower base resistance and parasitic capacitance. Analog ICs, such as AGC and post amplifiers, for repeater circuits of a high speed optical fiber transmission system were fabricated, and the following excellent characteristics were obtained.

(1) The gain and 3 dB down bandwidth of the post amplifier are 15 dB and 1.4 GHz, respectively.

(2) The maximum gain, 3 dB down bandwidth and dynamic range of the AGC amplifier are 28 dB, 630 MHz and 30 dB, respectively.
Process Parameter Control in Optical Lithography
Authors: Antognetti Paolo , Fasce Claudio , Oldham William
Published: March 2014

Today in projection lithography the loss in useful resolution stems primarily from the problem of process control. Unavoidable variations in process parameters produce either unacceptable variations in resist linewidth, or result in “unresolved” features-lines missing or spaces not cleared. In this paper simulation is used to perform quantitative studies on the sensitivity of critical dimensions of positive resist profiles with respect to variations in resist thickness T, illumination dose and development time t
dev. A modified version of the simulation program SAMPLE was used.1) The results obtained show that:
1) In most cases exposure and development time trade off with little effect on linewidth control;
2) Greater linewidth control may be achieved at the expense of minimum linewidth;
3) The use of post-exposure bake generally improves linewidth control, and, significantly, resolution on aluminum substrates with steps;
4) Linewidth control and practical resolution are drastically increased by planarization and elimination of reflections; a combination of both techniques can extend lithography to the sub-micron regime.
(Invited) Controlled Oxygen Doping in Silicon
Authors: Watanabe M. , Usami T. , Takasu S. , Matsuo S. , Toji E.
Published: March 2014

Oxygen concentration in as-grown silicon crystals was controlled by doping oxygen intentionally. Oxygen concentration depended linearly on the surface area of fused quartz pieces placed at the bottom of Si3N4 crucible which is made by CVD using SiCl4+NH3→Si3N4 reaction.
The Use of Selective Annealing for Growing Very Large Grains in Silicon on Insulator Films
Authors: Colinge J. P. , Demoulin E. , Bensahel D. , Auvert G.
Published: March 2014

The selective annealing technique (laser annealing under patterned antireflecting coating) has been successfully applied to the growth of very large (20 µm × 3000 µm) silicon single crystals. The grain boundary location is controlled by a conventional lithography step, and the grains obtained have a nearly perfect rectangular shape.
Comparison of Defect Formation in InGaAsP/InP and GaAlAs/GaAs
Authors: Ueda Osamu , Komiya Satoshi , Yamakoshi Shigenobu , Umebu Itsuo , Akita Kenzo
Published: March 2014

Crystal defects in InGaAsP/InP and GaAlAs/GaAs, induced by carrier injection and those by heavy doping were investigated by transmission electron microscopy, scanning electron microscopy and energy dispersive X-ray spectroscopy. Recombination-enhanced dislocation glide motion and climb motion often occurred in GaAlAs/GaAs DH LED's, but did not occur in InGaAsP/InP DH LED's. Furthermore, faulted loops were often observed in heavily doped GaAlAs crystals. However, in heavily doped InGaAsP LPE crystals (λ=1.3 µm), no loops were observed, and only non-structural precipitate-like defects were observed. The difference in the occurrence of dislocation glide motion and climb motion between these two materials could be well explained by considering the generation of faulted loops and dislocation loops in heavily doped crystals.
Effect of Nonuniformity in Temperature Distribution in a Stripe-Geometry Double-Heterostructure Laser
Authors: Hsieh H. C. , Lee G. Y.
Published: March 2014

The effect of nonuniformity in temperature distribution on the lateral mode guiding in a stripe-geometry double-heterostructure laser is investigated theoretically with the aid of a mathematical model which properly takes into account lateral current spreading, carrier diffusion, two-dimensional heat diffusion, and the variations of gain and refractive index parallel to the junction planes. The effective dielectric constant method, with parabolic approximation, was used in solving the resulting two-dimensional wave equation. Calculated results, which are generally in reasonably good agreement with existing experimental data, show that lateral thermal guiding may exist, in addition to gain-guiding for CW operation.
N+ Self-Aligned MESFET for GaAs LSIs
Authors: Yamasaki Kimiyoshi , Asai Kazuyoshi , Kurumada Katsuhiko
Published: March 2014

The SAINT (Self-Aligned Implantation for N+-layer Technology) procers can embed n
+-
layers with very low resistance at a controlled distance from Schottky gate. It has been experimentally ascertained that the SAINT has feasibility for GaAs LSIs with advantages of gain, speed, uniformity and stability. An optimum n
+-gate spacing in view of resistance-capacitance trade-off is found by combination of experiments and two-dimensional simulation. Guiding principles for the submicron gate are quantitatively discussed with results of the simulation.
Implantation into an AlGaAs/GaAs Heterostructure
Authors: Nishi Hidetoshi , Inada Tsuguo , Saito Junji , Ishikawa Tomonori , Hiyamizu Satoshi
Published: March 2014

Experimental results obtained for the implantation into MBE grown AlGaAs/GaAs heterostructures are reported in this paper. The electrical activation of implanted Si atoms takes place at an annealing temerature as low as 625°C in GaAs. In AlGaAs, it requires temperatures higher than 700°C, probably due to a higher density of defects remaining there than in GaAs. It is also clearly shown by Shubnikov-de Haas measurement that two-dimensional electron gas (2DEG) accumulates at the interface of low-dose Al implanted AlGaAs/GaAs heterostructure after annealing at 700°C, which indicates that implantation doping can be applied to AlGaAs/GaAs heterostructure for practical use while maintaining the essentiaal transport properties of 2DEG at the interface.
(Invited) Silicon TFTs for Flat Panel Displays
Authors: Morin François
Published: March 2014

A general investigation of flat panel displays, leads to the conclusion that an electrooptic transducer (liquid crystal for instance) operates in optimized conditions when directly driven by an active matrix system. Such a matrix can be fabricated by different procedures, but one of the most promising is the a-Si TFT technology. a-Si TFT seems quite suitable for LC driving, nevertheless polysilicon TFT should be preferred for fast peripheral addressing circuits. Two basic TFT processes are proposed, using a-Si and SiO2 films deposited on glass by the glow discharge technique. In the first process, silicon was deposited at 300°C instead of 500°C in the second. Only in this last case silicon could be easily recrystallized to get polysilicon TFT on glass. In this paper, the major attention was focused on amorphous Si TFT. Static and dynamic characteristics are presented putting forward the predominant role of traps, and a LC switching simulation is shown. Finally a large area circuit is proposed and the relevant problems discussed.
A Screen Printed CdS/CuInSe2 Solar Cell
Authors: Garcia Francisco J. , Tomar Maharaj S.
Published: March 2014

We report here the initial results of polycrystalline, 1 cm2, CdS/CuInSe2 solar cell, where both materials are successibely deposited by screen printing and sintering of pastes which contain the semiconductors. Indium chloride is used as adopant in the CdS paste. Typically these cells produce energy conversion efficiencies of around 3%, under 80 mW/cm2 ELH illumination. These preliminary results indicate the possibility of using ternary I-III-VI2 semiconductors as the absorber material in solar cells produced by the low cost technique of screen printing.
Novel Gate-Protection Devices for MOSFET's
Authors: Yoshida Isao , Okabe Takeaki , Ashikawa Kazutoshi , Ootaka Shigeo
Published: March 2014

Novel gate-protection devices for vertical-type power MOSFET's are developed utilizing a poly-Si film on an insulator. It is shown experimentally that, a breakdown voltage higher than 20 V, a leakage current of about 0.1 A/cm2, and a destructive breaking strength more than 300 V satisfy specifications for gate-protection devices. Power MOSFET's with the gate-protection device show remarkably reduced gate short characteristics against a simulated static discharge.
These latch-up free, gate-protection devices should prove very useful for every type of MOS device.
Compatible High and Low Voltage CMOS Devices Using SIMOX Technology
Authors: Akiya Masahiro , Nakashima Sadao , Kato Kotaro
Published: March 2014

New type high and low voltage CMOS buried channel devices are described, which are applied to a current mirror and an operational amplifier using SIMOX technology. In the MOS current mirrors, a 0.5% matching error rate was obtained in a 10 µA drain current without any compensation circuits. In the two stage operational amplifier, an open loop voltage gain of 60 dB was obtained with a ±5 V supply.
Experimental Investigation of an Acoustic Method to Estimate Fish Abundance Using Culture Nets
Authors: Furusawa Masahiko , Ishii Ken , Miyanohana Yoichi , Maniwa Yoshinobu
Published: March 2014

Using an acoustic method fish abundance in many culture nets has been measured and the results statistically analyzed. The acoustic system consists of two parts, an echo-integrator which gives distribution density and a specially designed sectorscanning sonar which provides distribution volume. By matching the measured numbers to actual ones, parameters concerning the target strength of fish and the attenuation by schooling fish are derived. These parameters are compared with actual observations.
Multichannel Transducers
Authors: Kojima Tadashi , Takahata Kazuo , Kasai Makoto
Published: March 2014

By affixing λ/4, 1.5λ/4, 3λ/4 or similar high-impedance acoustic plates to piezoelectric vibrators, high-sensitivity transducers with multiple channels and usable in liquid acoustic media were developed. The trial-manufacture of such transducers is described and an analysis of their operation is presented.
An Optical Fiber Hydrophone Using Polarization-Maintaining Fiber
Authors: Takahashi Sumio , Kikuchi Toshiaki , Okura Koji
Published: March 2014

The stability of output signal of a heterodyne optical fiber hydrophone using polarization-maintaining fiber is investigated. Using polarization-maintaining fiber, fluctuations of frequency-modulated beat signal decrease and the stability of demodulated output signal increases. Measured acoustic sensitivity of the polarization-maintaining fiber is 3.8×10-16 radµPa, while that of a conventional single-mode fiber is 1.2×10-15 rad/µPa.
Finite-Element Analysis of Periodic Waveguides for Acoustic Waves
Authors: Koshiba Masanori , Mitobe Seiichi , Suzuki Michio
Published: March 2014

A numerical approach based on the finite-element method is described for the analysis of periodic waveguides for acoustic waves. The validity of the method is confirmed by comparing the numerical results for the dispersion curves of horizontal shear (SH) surface wave propagation along a corrugated surface of an isotropic material with the experimental results. We also demonstrate the application of this approach by investigating the propagation characteristics of SH surface waves on corrugated layered surfaces of isotropic materials and of SH surface waves propagating under a metallic grating on a surface of a hexagonal piezoelectric crystal.
Group Carrier Supply Ceramic Filter
Authors: Inoue Takeshi , Kagaya Isao , Takahashi Sadayuki
Published: March 2014

A group carrier supply ceramic filter for use in an FDM carrier system was examined. For the filter, a ladder filter configuration composed of nine wire-mounted ceramic disk resonators and eight multilayer ceramic capacitors was adopted. Because of refinement of the filter design, only rough adjustment was fully sufficient for the frequency adjustment on the resonator. The filter exhibited analogous characteristics designed according to image parameter theory; both its temperature and aging characteristics were satisfactory. The stopband attenuation was more than 100 dB, due to suppression of spurious vibration. The filter size was reduced to 1/2 that of the usual quartz crystal filter.
SAW Convolver Using Curved Waveguide
Authors: Kitano Toshihiko , Nishikawa Katsuhiko
Published: March 2014

A SAW convolver with curved waveguide has been developed. This structure makes it possible to realize longer integration time in comparison with the conventional straight waveguide, in which the time extension is limited by the substrate size. A convolver with 29 µs integration time has been fabricated on a commercially available Y-cut LiNbO3 3'' wafer.
A Frequency Modulator Using a Lamb Wave Delay Line Oscillator
Authors: Toda Kohji , Mizutani Koichi
Published: March 2014

A Lamb wave device for frequency modulation is described which consists of two pairs of interdigital transducers and one electrode on a piezoelectric thin plate. Each of the transducers has the counter plate electrode on the opposite plate surface from the other. The oscillation frequency of the device varies linearly with the amplitude of an electrical signal applied to the central electrode. The operation principle for a frequency modulator is presented with confirming experimental results, including the voltage-frequency relation and the frequency characteristic.
Ultrasonic Imaging by Impulse Ultrasound
Authors: Okuyama Daitaro , Yoshida Yasuo
Published: March 2014

An impulsive ultrasound wave as membrane radiated from a transmitter, a thick piezoceramic transducer, is used for ultrasonic imaging. The transmitter is fixed and a probe type hydrophone with tiny piezoceramic transducer moves just a few millimeters from the radiation surface. An object is set very close to or put onto the radiator surface. The image is characterized by the amplitude and the transit-time of the penetrating wave through the object. A coded ultrasonic pulse train is also used to make ultrasonic images.
Synthetic Aperture Acoustic B-Scope Imaging Using the FFT
Authors: Nagai Keinosuke
Published: March 2014

A new numerical image-reconstruction method for the acoustic B-scope is proposed and the point spread function of such imaging system is obtained experimentally.
Recently the synthetic aperture method has been applied to acoustic B-scope imaging to improve its transversal resolution. This report presents another synthetic aperture method which involves calculations in the Fourier domain. The new method results in a better transversal resolution and side-lobe-reduction than the conventional synthetic aperture method.
Excitation of Surface Acoustic Waves Using Electron Acoustic Microscope
Authors: Yamanouchi Kazuhiko , Kudo Satoshi , Wagatsuma Yasuo
Published: March 2014

A focused, modulated electron beam can generate acoustic bulk waves and surface acoustic waves (SAW) at the surface of a front specimen. By conventional electron acoustic microscope the acoustic bulk waves are detected by a piezoelectric transducer at the rear surface. In this paper, acoustic surface waves which are effectively excited by electron beams are detected at the surface of the specimen. This technique gives better imaging than the bulk wave detection.
Propagation Properties of Ultrasound in Acoustic Microscopy through a Double-Layered Specimen Consisting of Thin Biological Tissue and Its Holder
Authors: Tanaka Motonao , Ohkawai Hiroaki , Chubachi Noriyoshi , Kushibiki Jun-ichi , Sannomiya Toshio
Published: March 2014

In transmission mode SAM, a biological tissue section to be examined is usually mounted on a polyester film holder to compose a double-layered specimen. In this paper, a one dimensional acoustic model for double layers composed of the mounting holder and a tissue section is investigated to discuss the propagation properties through the specimen quantitatively. It has been basically clarified that variations of brightness in the amplitude image correspond to those in acoustic absorption and that variations of brightness in the phase image correspond to those in sound speed in the tissue section.
Characterization of Ferroelastics by Scanning Acoustic Microscopy
Authors: Kojima Seiji
Published: March 2014

Ferroelastic crystals have been studied by SAM. The fringe patterns of the acoustic image around the domain boundary of NdP5O14 have been investigated at the operating frequencies of 200 MHz and 420 MHz. The wavelength λR of the leaky Rayleigh wave propagated perpendicular to the boundary has been determined from the null spacing of the V(z) curve measured by utilizing a cylindrical acoustic lens. It is confirmed that the space of the fringe is equal to λR/2. The discontinuity angle at a domain boundary of NdP5O14 has been determined from another interference fringe due to the inclination around the boundary.
Spectrum of Echo Scattered by Inclined Plane
Authors: Ueda Mitsuhiro , Tabei Makoto , Tsuji Masanobu , Imaizumi Hiroyuki
Published: March 2014

In this paper a spectrum of an echo scattered by an inclined flat surface is analyzed theoretically using a mathematical description of the echo signal based on a discrete expression of scatterers. The analysis shows that the spectrum can be characterized by two parameters, a normalized inclination angle and a Fresnel number, and is proportional to the frequency of ultrasonic waves hyperbolically. Theoretically estimated spectra are compared with those obtained experimentally with rather good agreement.
Surface Waves on Liquid Helium
Authors: Iino Masaaki , Suzuki Masaru , Ikushima Akira J. , Okuda Yuichi
Published: March 2014

Three types of surface waves on liquid He were observed with high precision by a new method using a capacitive technique and phase locked loop. This method is not accompanied by any energy dissipation and is consequently suitable for experiments at ultralow temperatures. We demonstrate measurement of the capillary wave velocity to obtain the surface tension of bulk liquid He.
Magnetophonon Resonance in n–InP
Authors: Nakashima Takashi , Hamaguchi Chihiro , Komeno Jyunji , Ozeki Masashi
Published: March 2014

Magnetophonon oscillations have been measured in the transverse magnetoresistance of high purity epitaxial n–InP using a magnetic field modulation technique. Resonance peaks up to N=9 are observed at temperatures between 100 and 250 K. The band edge effective mass is estimated to be 0.0815±0.0005 m at 110 k and 0.078±0.0005 m at 240 K. The temperature dependence of the effective mass is discussed using Kane's 3 band model and the momentum matrix element is determined to be P2=16.3 [eV].
Measurement of Cylindrical Flaws using Pitch-Catch Method
Authors: Umeda Akira , Hida Namiteru
Published: March 2014

This paper is concerned with the localization and size estimation of cylindrical flaws which are included in materials with flat surfaces. A pair of longitudinal wave probes is used for localization; for sizing, three transducers are used. Simulation and experiments demonstrated that localization is possible even when scanning is limited because of the geometrical configuration of a specimen. The validity of flaw sizing was also shown by experiments. The possibility of size estimation of inner flaws even under the condition of limited scanning is demonstrated.