Dip Area Research Articles

Transonic Flutter Dips of the AGARD 445.6 Wing

The AGARD 445.6 configuration is the most popular validation test case for transonic flutter predictions, but the actual extent of truly nonlinear transonic flow for this case is unclear, due to the sparsity of the experimental data and the thin profile of the wing. This work utilizes a combination of mesh adaptation and the linearized frequency-domain method to obtain high-quality viscous and inviscid flutter predictions; these solutions show a double flutter dip through the transonic Mach range driven by complex shock growth across the wing. A single experimental flutter point lies in this flutter dip area, which is not enough to assess the accuracy of these transonic flutter predictions. Modeling the boundary layer of the wind tunnel wall (as opposed to the commonly assumed symmetry wall assumption) has a very large impact on the predicted flutter boundary, though the size of the boundary layer during the original experiment is uncertain.

Rapid and high-precision displacement sensing based on the multiple mode dip areas in a SNAP microresonator.

Whispering gallery mode (WGM) microresonators offer significant potential for precise displacement measurement owing to their compact size, ultrahigh sensitivity, and rapid response. However, conventional WGM displacement sensors are prone to noise interference, resulting in accuracy loss, while the demodulation process for displacement often exhibits prolonged duration. To address these limitations, this study proposes a rapid and high-precision displacement sensing method based on the dip areas of multiple resonant modes in a surface nanoscale axial photonics microresonator. By employing a neural network to fit the nonlinear relationship between displacement and the areas of multiple resonant dips, we achieve displacement prediction with an accuracy better than 0.03µm over a range of 200µm. In comparison to alternative sensing approaches, this method exhibits resilience to temperature variations, and its sensing performance remains comparable to that in a noise-free environment as long as the signal-to-noise ratio is greater than 25dB. Furthermore, the extraction of the dip area enables significantly enhanced speed in displacement measurement, providing an effective solution for achieving rapid and highly accurate displacement sensing.

A case study on control technology of surrounding rock of a large section chamber under a 1200-m deep goaf in Xingdong coal mine, China

The drainage system chamber with a net section of 68.3 m2 requires excavation under a 1200-m deep goaf, which is determined by geological conditions of production containing the mining layout and excavation system, hydrogeology, and actual water gushing at −980 mining level dip area of Xingdong coal mine. The chamber and its surrounding rock influence area are arranged in the large-range stress-released zone of the floor of 2127 goaf to effectively improve the basic stress environment of the chamber's surrounding rock and to eliminate or weaken the influence of deep high stress and rock mass rheological properties on the continuous large deformation of the surrounding rock. However, the surrounding rock of the chamber is completely in the plastic zone. Thus, it will remain subject to more severe support problems. In view of the control problem of the surrounding rock of the large section chamber under the 1200-m deep goaf, this paper proposes a comprehensive control technology using the strong anchor bolt (cable) support, pouring of thick reinforced concrete wall, and full section pressure-regulating grouting behind the wall. It also clarifies the supporting mechanism on the basis of the pressure relief of the chamber's surrounding rock. Engineering practice shows that the large section chamber has not been renovated, and the maximum deformation of the surrounding rock is only 50 mm in over four years since the completion of construction. Thus, this technology has achieved a long-term effective control with no refurbishment after supporting the large section chamber under the 1200-m deep goaf. Furthermore, it enriches the control theory and technology for the surrounding rock of deep roadways.

Baseline Systolic versus Diastolic Blood Pressure Dip and Subsequent Visual Field Progression in Normal-Tension Glaucoma

To investigate the impact of systolic and diastolic blood pressure (DBP) dip at baseline on subsequent visual field (VF) progression in eyes with normal-tension glaucoma (NTG). Prospective cohort study. This study included 119 eyes of 119 newly diagnosed NTG patients followed up for at least 2 years (average, 40.4±16.9 months). All participants underwent baseline 24-hour ambulatory blood pressure (BP) monitoring and measurements of intraocular pressure (IOP) and at least 5 serial VF examinations. Participants were followed up as outpatients at 4- to 6-month intervals. Visual field progression was defined according to Early Manifest Glaucoma Trial criteria. The associations of VF progression with systolic BP (SBP) and DBP measured during the day and at night and other clinical variables were analyzed. Factors associated with VF progression over time. During follow-up, 41 eyes (34%) showed VF progression. In the multivariate Cox regression model, lower nighttime trough DBP (hazard ratio, 0.953; P= 0.023) and greater nighttime DBP dip area (time multiplied by nighttime DBP > 10 mmHg less than mean daytime DBP; hazard ratio, 1.017; P= 0.003) at baseline were significant predictors of subsequent VF progression. None of the SBP parameters was associated with VF progression. Nocturnal DBP dip showed a greater association with VF progression than SBP dip. Nocturnal trough DBP and DBP dip area at baseline are significant predictors of subsequent VF progression in NTG. Nocturnal DBP dip may be more relevant to future VF progression than SBP dip in NTG eyes.

Seismic Attribute Analysis for Reservoir Description and Characterization of M-Field, Douala Sub-Basin, Cameroon

Complexity of discontinuous reservoir units occurring within the shale-rich N’kapa Formation and the limitation of well-articulated interpretations deduced from 2D seismic data, led to a new approach of interpretation of the 3D seismic data of M-Field located offshore Douala Sub-Basin, Cameroon. The study aimed at determining the subsurface distribution of the delineated reservoir units in terms of geology, structures, stratigraphic architecture as well as the lateral and vertical distribution of each of the reservoir units across the field.Well log signatures were analyzed and interpreted to identify hydrocarbon bearing sands, which were subsequently mapped to the 3D seismic record using the generated 1D synthetic seismogram to tie the well information to the seismic volume. The delineated hydrocarbon bearing sand bodies were mapped as horizons on the 3D seismic record in addition to subsurface structural mapping to generate subsurface depth structure maps. Further still, amplitude variation surface seismic attribute analyses aid the delineation of geometry of depositional channels across the M-Field. Two horizons ( X 1 and Y 1 ) were interpreted and used to generate surfaces attribute maps. The M-Field reservoirs present stratigraphic architecture which suggests levees or confined channel sands deposit as the dominant channel deposit. X 1 and Y 1 are stratigraphic trappedhydrocarbon systems, however, while X 1 is located up-dip, Y 1 is situated on a monoclinic slope in the down dip area of X 1 , such that Y 1 stratigraphically seats on X 1 but eroded around X 1. The high amplitude associated with the delineated erosional surface likely results due to difference in acoustic properties across the interface owing todifference in age and composition of the two units. This suggests that the delineated reservoirs are two different units which are not correlateable as earlier postulate.

Simulating the effect of rake angle on narrow opener performance with the discrete element method

Narrow openers are widely used in Australia to place seed and fertiliser into furrows under no-tillage seeding operations, but excessive soil disturbance often limits their performance. The discrete element method (DEM) and a hysteretic spring contact model can be used to model soil-tool interactions, although previous work has been limited in its evaluation of soil disturbance. A new approach was used to evaluate soil disturbance in DEM simulations using a voidage grid binning technique to identify loosened soil after tillage and therefore paralleling soil bin and field testing methodologies. The effect of opener rake angle (35–90°) was simulated and compared to previous soil bin studies in a sandy loam soil predicting furrow profile parameters loosened area, ridge height, dip area, furrow backfill and lateral soil throw with relative errors of 9%, 16%, 14%, 0.8%, and 9%, respectively. Soil layer mixing trends also followed those measured in soil bin experiments-low rake angle openers moving deep soil up the furrow profile and maximising the furrow mixing effect. Additionally, predicted soil failure (critical depth and forward rupture ratio m) and tillage force rake trends followed those expected from classic empirical based soil mechanics studies. DEM predicted approximately a twofold draught penalty with increasing rake angle as well as a vertical force transition at 71°–closely matching trends consistently reported in literature. The approach followed demonstrated an improved potential for DEM simulations to optimise the performance of narrow openers.

The hydrocarbon trap distribution patterns of the simple dip area of a continental basin: A case study from the western slope of the Songliao basin, China

Simple dip areas of continental sedimentary basins feature stratal overlap, gentle changes in slope, uniform dip angles, and minimal fault development. Locating hydrocarbon traps in these environments therefore presents a difficult challenge. This paper analyzes reservoir sand body and hydrocarbon trap development and their distributions within the gently dipping western area of the Songliao basin and discusses the determinants influencing the distribution of reservoir sand bodies and oil and gas bearing zones. Sand bodies within the simple east-dipping western basin margin exhibit thin singular layering, extensive planar distribution, and frequent interbedding with mudstone layers. In the homoclinal slope areas that lack significant fault development, sand bodies served as important hydrocarbon migration pathways. Spatial shifts in the paleosedimentary system caused by basin subsidence and late stage tectonism can help constrain the search for hydrocarbon traps. The spatial patterns of the depositional system influenced the distribution of different types of traps. Southerly prograding delta lobes were subsequently tilted to the east, creating sand bodies that form up-dip, wedge-out lithologic–stratigraphic traps along their western edge. Some of the delta lobes are folded or cut by faults along their peripheral edges, making structural traps and combination traps, the primary types in this region. The delta lobes in the western provenance system, however, dip in a direction parallel to that of sediment supply. Most subaqueous distributary channel sand bodies are continuous into the western source area and lack seal conditions. Lenticular lithologic traps are therefore found only along the outer edges of delta lobes and the adjacent shallow lacustrine environments.

Occurrence Features of Coalbed Methane in Inclined Coal Seam of Junggar Basin, Xinjiang

Junggar Basin is located in north Xinjiang and it has a huge amount of coalbed methane resources with less exploration and mining. The most vital characteristic in junggar basin is coal dip angel and gas content varies a lot in different areas. This paper reveals the relationship between gas content and coal seam dip angel, bigger the coal seam dip angel lower the gas content. The target area of CBM exploration and mining in junggar basin is HEGSH-STH area, HEGSHX area, BSMY-JJM area,LJM area, KLMY area, HSTLG area and XZJQ area. Gas content is mainly influenced by tectonic movement in junggar basin, it is low in complex structure area and high in simple structure area. Inclination of the coal seam stands for the complexity of the structure in junggar basin, the structure is complex when the coal seam is steep, it is simple when the coal seam is flat. The result can be used as a new method for coalbed methane exploration and development in inclined coal seam areas, small coal dip area should be chosen as the high gas content target.

Voltage Profile Analysis during Fault with STATCOM

This paper deals with comparative study of voltage and angle stability analysis with and without STATCOM. This paper makes the assumption that under voltage is caused by a Single phase to ground fault. Single phase to ground fault is applied in IEEE 57 bus system for analysis the effected voltage dip area in IEEE 57 bus system. The effect of fault on voltage profile and angle of IEEE 57 bus system has been analyzed with and without STATCOM. The studies are performed based on MATLAB software package tool box.

Coherent operation of photon subtraction and addition for squeezed thermal states: analysis of nonclassicality and decoherence

We study nonclassical properties of the optical field when photon subtraction/addition coherent operation ta+ra† (|t|2+|r|2=1) acts on a squeezed thermal state (STS) by examining its quadrature squeezing, sub-Poissonian statistics, and negativity of the Wigner function. The degree of squeezing of the coherent operated squeezed thermal state (COSTS) becomes weaker. The Mandel Q parameter decreases with r and quickly becomes negative, which implies sub-Poissonian statistics. Both the negative dip and negative area of the Wigner function increase with r for small squeezing values of κ. Decoherence of the COSTS in an amplitude-damping channel is studied by the time evolution of the Wigner function. The length of time that this nonclassical field preserves its partial negativity of the Wigner function can be modulated by the coherent operation. All these results indicate that the nonclassicality of the STS is sensitive to the coherent operation.

Electrical resistivity dip in Sb x V y Mo z O t phases

Electrical resistivity dips have been discovered in the temperature range 100–500 K both in the SbVO4.96 matrix and the Sb x V y Mo z O t phases for 10 mol% solubility of MoO3 in SbVO5. As the Sb content increases and simultaneously the V content decreases, the value of the resistivity at the dip, ρ d, decreases and shifts the dip to higher temperatures. The magnetic measurements showed a spontaneous magnetization and parasitic magnetism of the solid solutions under study. Characteristic for parasitic magnetism is a small value of the magnetic moment, here 0.014 μ B/f.u. at 4.2 K and at a magnetic field of 14 T as well as a small value of the mass susceptibility, here 10−5 cm3/g. The value of the Néel temperature, T N ≤ 8 K, and the Curie–Weiss temperature, θ CW ≤ −208 K, indicate a collinear antiferromagnetic (AFM) order. We suggest that neither the magnetism nor the Mo-content can be correlated with the resistivity anomalies. Therefore, these effects may rather be interpreted in terms of a small-polaron gas in the resistivity dip area. Alternatively, they could mark a lattice/electronic entropy-driven incomplete metal–insulator transition.

ガス抜き座毎のガス抜き量の計測結果について 沿層ボーリングによる地山ガス抜き量の計測 （第１報）

Continuous measurement on gas drainage was carried out at 22 drilling sites of No.1 and No.3 slope area in Minami-Oyubari coal mine. In this coal mine, methane drainage method from seam-road using each drilling site where 40-60 boreholes were drilled as gas drainage area has been developed.The results obtained are as follows.1) Patterns of gas drainage at each drilling site can be divided into three types according to geological conditions.2) With the exception of one example, it is recognized that cumulative gas drainage volume was in proportion to the peak value of gas drainage rate.3) Cumulative gas drainage volume, cumulative gas drainage volume per coal reserve within the boring area of fan-shape and cumulative gas drainage volume per boring meter related to No.1 slope area were different from these related to No.3 slope area. These values of No.1 slope area were respectively 3.1, 3.7 and 2.4 times compared with No.3 slope area.4) With gas drainage at each drilling site of No.3 dip area, the peak value of gas drainage rate at drilling sites with faults was about 2.0 than this value at drilling sites without faults.5) Relationships between boring length per 1m2 of gas drainage and cumulative gas drainage per coal reserve divided according to geological conditions are recognized.

Heart rate and blood pressure response and metabolic changes in the sheep fetus following reduction of uterine blood flow.

The cardiovascular and metabolic responses during acute fetal hypoxia were studied in 7 pregnant sheep near term. Complete reduction of uterine flow (UBF) for 180 s was performed in 13 experiments by inflating a balloon positioned in the maternal aorta. Fetal heart rate (FHR), systolic and diastolic blood pressure (BP) and fetal arterial oxygen saturation (SO2) were measured continuously. Blood samples were taken at short intervals and analyzed for pH, PCO2, PO2, SO2, base excess and lactate. Following the reduction of UBF, FHR began to rise after 4.7 +/- 14.4 (SD)s and fell after 31.3 s paralleled by the rise of the BP after 23.2 +/- 8.2 (SD)s. The fall of FHR was not related to the SO2 at control, but to the decline of the SO2 by 10-15%. There was no critical limit of SO2 at which the FHR started to fall and the BP began to rise. The rise of the FHR after UBF had been released was significantly correlated to the rise of SO2. Lactate production during hypoxia was related to the slope of the SO2 decline, i.e., to the fetal O2 consumption. The total metabolic response during hypoxia and recovery given by the pH area was correlated to the SO2 at control. No correlation between dip area of FHR and PH area could be established.

Dip area in fetal heart rate and its relationship to acid-base-observations of fetus and mother during labor

The relationship between dip area (DA) of fetal heart rate (FHR) and the acid base status of fetus and mother during the first and second stage of labor were studied on 39 women at term. The observations reveal a significant correlation between the fall in fetal base excess (BE) and the measured DA: deltaBE = 0.01 - 0.143 DA (2alpha less than 0.01). There is no difference in the correlation of these parameters between the first and the second stage of labor despite the fact of a greater fall in BE and a greater DA per time compared to the first:BE meq/1/10min. 0.14 (SD 0.26) and 0.76 (SD 0.62); DA cm2/10 min. 0.99 (SD 1.19) and 4.28 (SD 3.06), respectively. With increasing DA the variance of the fall of fetal BE (S2BE) rose also: DA of 0-5 cm2: S2BE 0.66; DA greater than 15.1cm2:S2BE 3.76. With the fall in fetal BE there was also a fall in maternal BE, more pronounced during the second stage of labor:-BEF=0.38.DELTA BEM-0.70(2alphaless than 0.01). The fraction of the fall in fetal BE per DA increased with the fall in maternal BE (2alpha less than 0.05). This correlation reveals that there might be a slight influence of maternal BE on fetal BE. The present observation shows that measuring DA serves only as an approach to predict fetal condition during labor. It therefore should be combined with fetal scalp blood sampling. The influence of maternal BE on fetal BE seems to be only of less importance.

Quantitative relationships between slowing of the fetal heart rate and changes in base-excess in the second stage of labor.

The partial pressure of oxygen in the blood of the scalp and that of the umbilical artery of the fetus is lowered during the first and second stage xpJE labor, if there is a slowing of the heart rate in conjunction with uterine contractions (CALDEYRO-BARCIA et al. [2]; KUNZEL [4]). In animal experiments the reduction of uterine blood flow was shown to be a cause of this deceleration (JUNGE, KUNZEL, KLOCK [3]). Since the duration of the reduced blood flow corresponds well to the duration of the deceleration and hypoxia, it might be assumed that the dip area is an indication of the hypoxia and the resulting metabolic acidosis. This is even more probable since TIPTON and SHELLEY [6] have shown a definite relationship between the dip area and clinical Parameters. We have attempted to find out whether there is a quantitative relationship between the dip areas measured before birth and the metabolic changes in the blood of the fetus so that an increase in the deficit in the fetal blood can be estimated more precisely. The examinations showed a good relationship between such a dip area and the increased base excess in the fetal blood.

Neutron Resonance Spectroscopy. XIV. Potassium

Results are presented of high-resolution transmission measurements using pure natural K metal samples. The measured total $\ensuremath{\sigma}$ vs $E$ to 400 keV is given, and resonance parameter evaluations are given for 65 resonances below 200 keV. The isosopte assignments, $A=39 or 41$, are mainly based on recent unpublished measurements of Good and Harvey at the Oak Ridge electron linear accelerator using separated K isotope samples. Values of level strengths, $\mathrm{ag}{\ensuremath{\Gamma}}_{n}$, are mainly based on transmission dip area analysis, which with evidence from the resonance shape and peak cross sections permits assignment of $l$ and $J$ for most resonances, and $A$ for many of the resonances not identified in the separated isotope measurements. We obtain for the $s$ and $p$ strength functions: $10^{4}S_{0}=({0.66}_{\ensuremath{-}0.30}^{+0.63}),({0.78}_{\ensuremath{-}0.41}^{+1.08})$, and $10^{4}S_{1}=({1.8}_{\ensuremath{-}0.5}^{+0.7}) \mathrm{and} ({2.4}_{\ensuremath{-}0.8}^{+1.3})$ for $^{39}\mathrm{K}$ and $^{41}\mathrm{K}$, respectively.

An index of fetal welfare in labour.

SummaryAn index of fetal welfare in labour has been devised based upon the fetal basal heart rate, the dip area (Shelley and Tipton, 1971) and the presence or absence of meconium. This index appears to surpass other methods of predicting fetal outcome in labour.

Dip area. A quantitative measure of fetal heart rate patterns.

SummaryAnalysis of fetal heart rate records has shown that the frequency, duration and amplitude of transient episodes of fetal bradycardia, regardless of their relationship to uterine activity, are factors of great importance in assessing fetal condition. Dip area is a quantitative measure of these factors; it is easily communicated and avoids the present confusion of classification and nomenclature.

Effect of compound nucleus on blocking phenomena for energetic charged particles

The change of the dip area in the blocking pattern for energetic charged particles due to the formation of compound nuclei is calculated. A numerical example is given for the {111} planar blocking of protons in germanium.

Measurement of recoil-free fractions in studies of the Mössbauer effect

This paper discusses the techniques of measurement of recoil-free fractions ƒ of resonance gamma rays. A theoretical analysis extends the validity of the resonance dip area method, to permit relative ƒ measurements to be made on emission lines of arbitrary shape. The method is also applicable to relative ƒ′ measurements on thin absorbers. Some forms of instrumental broadening do not affect the result. A discussion on background intensity measurements includes some techniques for making precise background corrections. Absolute ƒ measurements are discussed in terms of a very wide absorption line, which can be considered to approach the ideal of a “black” resonance absorber. A mixture of fluoroferrates, having a composite line width of more than 1.4 mm/sec, has been developed. The preparation of nearly black absorbers by compounding the mixture with iron enriched in Fe 57, is described in a detailed recipe. The absorbers are so nearly ideal that many ƒ measurements can be made simply, comparing intensities transmitted by a stationary absorber with the corrected intensity transmitted at high Doppler shifts. These absorbers have been used to measure the ƒ of 14.4 keV gamma rays of Fe 57 in Cu, Pt, and Be hosts at room temperature. The results are ƒ( Cu) = 0.175 ± 0.021, ƒ( Pt) = 0.736 ± 0.023 ; ƒ( Be ∥ to c axis) = 0.805 ± 0.028; ƒ( Be ⊥ to c axis) = 0.809 ± 0.028 . Relative ƒ measurements, made with a potassium ferrocyanide absorber, are in agreement with the ratios of the absolute ƒ values.