一种基于IF模型侧抑制神经网络群的PITS学习算法

构建了一种基于IF模型的侧抑制神经网络群,用以实现位置定位.采用基于H-H模型简化的IF模型构造神经网络群并基于概率密度分布进行位置定位.在神经网络群学习过程中,运用PITS(progressive interactive training scheme)方法进行参数学习,利用信息中心(IC)储存每次训练的结果,在保证输出收敛的情况下,比较跟踪结果的误差函数给出权值调整公式进行自学习.实验结果表明:基于IF模型构建的神经网络群可以实现位置定位.采用H-H模型简化的IF模型提高了学习效率和定位速度;运用PITS算法进行参数学习提高了定位精度.

Fractal Characteristic of Pits Distribution on 304 Stainless Steel Corroded Surface and Its Application in Corrosion Diagnosis

Electrochemical techniques and fractal theory were employed to study the corrosion behaviors and pits distribution characteristics on the corroded surfaces of 304 stainless steel exposed in FeCl3 solution. Fractal features of pits distribution over the corroded surfaces were observed and described by the fractal dimension. A 5-8-2 back-propagation （BP） artificial neural network model for the diagnoses of the pitting corrosion rate and pits deepness of 304 stainless steel under various conditions was developed by considering the fractal dimension as a key parameter for describing the pitting corrosion characteristics. The predicted results are well in agreement with the experimental data of pitting corrosion rate and pit deepness. The max relative errors between their experimental and simulation data are 6.69% and 4.62%, respectively.

On the genesis of granite pits on top of the Shigujian Peak of the Dayangshan Mountain in Jinyun County,Zhejiang Province

On top of Shigujian Peak(1477 m a.s.l.) of the Dayangshan Mountain in Jinyun County, Zhejiang Province, large amounts of granite pits with diameters ranging from several dozens of centimeters to around one meter and depth from 10 cm to 45 cm are found on rock surface.These pits mainly appear on the NE and SE sides, and their drainage mouths are in the same direction.The identification results through micropolariscope and X-ray fluorescence spectrometer reveal that bedrock of pits is from middle to fine-grained moyite being apt to be weathered and modified.In Dayangshan region the annual mean temperature is 9.2℃ and annual precipitation is over 1700 mm.On the one hand, there always experiences a period of periglacial action with temperature oscillating near 0℃ for 4 months, i.e., from December to March next year.As a consequence, the freezing-thawing cycles may be remarkable to disintegrate the bedrock.On the other hand, the windward slope of Shigujian Peak meets typhoon of over force 10 on the Beaufort scale in summer, therefore, the blowing makes suspending sands or pebbles grind in swirling form.Based on field investigation and periglacial geomorphic theory, the pits on top of Shigujian Peak are attributed to freez-ing-thawing of periglacial action.Meanwhile, storm and strong wind accelerate the process.Observation shows that both the actions are still undergoing and variant directions of wind are the main cause for making different shapes of the pits.Because the top of Shigujian is 1500 m lower than the present snow line, some scholars considered that"glacial pothole"formed in the Quaternary is hard to work, even though in the Last Glacial Maximum(LGM).

Space-time principles of reducing stripping in furrow pits

The lower slope of furrow pits has following special features: small extent of weathering destruction, short time of production blasting damage, good arching effect of lower slope with small curvature radius, and good bottom effect of a pit end for transferring and bearing initial horizontal stresses in lower slope. The new principles provided theoretical basis for convex slope in furrow pits to reduce stripping. Similar phenomena and examples are supplied simultaneously.

Carrier transport via V-shaped pits in InGaN/GaN MQW solar cells

Carrier transport via the V-shaped pits （V-pits） in InGaN/GaN multiple-quantum-well （MQW） solar cells is numer- ically investigated. By simulations, it is found that the V-pits can act as effective escape paths for the photo-generated carriers. Due to the thin barrier thickness and low indium composition of the MQW on V-pit sidewall, the carriers entered the sidewall QWs can easily escape and contribute to the photocurrent. This forms a parallel escape route for the carries generated in the fiat quantum wells. As the barrier thickness of the fiat MQW increases, more carriers would transport via the V-pits. Furthermore, it is found that the V-pits may reduce the recombination losses of carriers due to their screening effect to the dislocations. These discoveries are not only helpful for understanding the carrier transport mechanism in the InGaN/GaN MQW, but also important in design of the structure of solar cells.

THE PITS PROPERTY OF ENTIRE FUNCTIONS DEFINED BY DIRICHLET SERIES

The value distribution of entire functions defined by Dirichlet series are studied in this present article.It is proved that entire functions defined by Dirichlet series have the pits property,which improve the relative results on lacunary Taylor series obtained by Littlewood J.E.and Offord A.C.

Light-extraction efficiency and forward voltage in GaN-based light-emitting diodes with different patterns of V-shaped pits

We present a new method of making a textured V-pit surface for improving the light extraction efficiency in GaN- based light-emitting diodes and compare it with the usual low-temperature method for p-GaN V-pits. Three types of GaNbased light-emitting diodes （LEDs） with surface V-pits in different densities and regions were grown by metal-organic chemical vapor deposition. We achieved the highest output power and lowest forward voltage values with the p-InGaN V-pit LED. The V-pits enhanced the light output power values by 1.45 times the values of the conventional LED owing to an enhancement of the light scattering probability and an effective reduction of Mg-acceptor activation energy. Moreover, this new technique effectively solved the higher forward voltage problem of the usual V-pit LED.

Effect of Mg-Preflow for p-AlGaN Electron Blocking Layer on the Electroluminescence of Green LEDs with V-Shaped Pits

In GaN-based green light-emitting diodes（LEDs） with and without Mg-preflow before the growth of p-Al GaN electron blocking layer（EBL） are investigated experimentally.A higher Mg doping concentration is achieved in the EBL after Mg-preflow treatment,effectively alleviating the commonly observed efficiency collapse and electrons overflowing at cryogenic temperatures.However,unexpected decline in quantum efficiency is observed after Mg-preflow treatment at room temperature.Our conclusions are drawn such that the efficiency decline is probably the result of different emission positions.Higher Mg doping concentration in the EBL after Mg-preflow treatment will make it easier for a hole to be injected into multiple quantum wells with emission closer to pGaN side through the（8-plane rather than the V-shape pits,which is not favorable to luminous efficiency due to the preferred occurrence of accumulated strain relaxation and structural defects in upper QWs closer to p-GaN.Within this framework,apparently disparate experimental observations regarding electroluminescence properties,in this work,are well reconciled.

Biodiesel Production from Oils Extracted from Date Pits

Biodiesel production had received a considerable attention as a green, non-toxic and renewable alternative to petroleum diesel. To avoid using vegetable oils, which are expensive and compete with food, as feedstock, waste oils have been proposed. However, these waste materials contain a large amount of free fatty acids that complicates the production process. In this work, biodiesel production using an alternative feedstock;namely oils from date-pits, has been investigated. These oils have the same favorable features of straight oils, and at the same time are considered waste, since they are extracted from a waste material. The yield of oils extracted using n-hexane in a Soxhlet apparatus was compared to that of oils extracted using methanol-chloroform solvent mixture. The extracted oils were then converted to biodiesel via transesterification with methanol in presence of Novozym&#174435 or Eversa&#174Transform. The highest oils extraction yield of 11.7%, per dry weight sample, was obtained using Soxhlet extraction apparatus compared to 8.9% using methanol-chloroform mixture. The highest biodiesel production yield was 30% of the oil used, achieved after 6 hours using Novozym&#174435 at 40°C, 5:1 methanol to oil molar ratio and 10wt% enzyme loading. By using a chemical alkaline catalyst, NaOH, at the same conditions, the yield was 27%.

Effect of Distance of Sanitary Pits on the Microbial and Heavy Metal Levels in Hand Dug Well Water Samples Consumed by People Living in Akwuke, Enugu South Local Government Area of Enugu State

Studies were carried out to assess the effect of distance of sanitary pits on the microbial and heavy metal levels in hand dug well water samples consumed by people living in Akwuke, Enugu South Local government area of Enugu State, using standard biochemical and spectrophotometric analysis. The well water samples were digested with aqua-regia and four heavy metals (Pb, Cd, Cu and Zn) were assayed in the well water samples at sampling distances of 3, 6 and 10 m respectively from the sanitary pits. The range of mean bacterial counts (cfu/g) for the four detected pathogenic bacteria; S. aureus, Klebsiella pnemeoniae, Echerichia coli and Salmonella enteritidis were 83 - 3730, 510 - 870, 50 - 2535 and 240 - 3420 Cfu/g at sampling distances of 3, 6 and 10 m respectively from the sanitary pits. The mean bacteria counts of the four detected pathogenic organisms in the well water sample at sampling distances of 3 and 6 m respectively from the sanitary pits were above the WHO recommended threshold limits for a safe drinking water. The mean bacterial counts of Salmonella enteritidis in the well water samples of sampling distance of 10 m from the sanitary pits was above the WHO recommended permissible limits. At sampling distances of 3, 6 and 10 m from the sanitary pits, the mean range of Pb, Cd, Cu and Zn in the well water samples were, 0.03 - 0.3, 0.02 - 0.05, 0.46 - 1.71 and 1.63 - 7.03 μg/g respectively. The mean levels of Pb and Cd in the well water samples at sampling distances of 3 and 6 m respectively from the sanitary pits were above their respective WHO recommended threshold limits. The mean heavy metals (Cd, Pb, Cu and Zn) in the well water samples at sampling distances of 3, 6, and 10 m respectively from the sanitary pits were statistically significant at p < 0.05.

Effect of Distance of Sanitary Pits on the Physicochemical Properties of Hand Dug Well Water Samples Consumed by People Living in Akwuke Community, Enugu South Local Government Area of Enugu State

Studies were carried out to evaluate the effect of distance of sanitary pits on the physicochemical properties of hand-dug well water samples consumed by people living in Akwuke community, Enugu South Local Government Area of Enugu State, using standard analytical procedures and instrumentation. The mean range of pH, turbidity, electrical conductivity, total dissolved solids, nitrate and sulphate in the well water samples at the determined sampling distances of 3, 6 and 10 m from the sanitary pits were 5.9 - 7.24, 1.92 - 6.63 NTU, 122.03 - 303.91 μs/cm, 100.00 - 261.90 mg/L, 1.21 - 4.68 mg/L and 28.89 - 49/61 mg/L respectively. The investigated mean physicochemical parameters of the well water samples were generally observed to increase with decrease in the distance of the well water samples from the sanitary pits. The levels of the determined physicochemical parameter of the well water samples at sampling distances of 3, 6, and 10 m respectively from the sanitary pits were statistically significant. The mean pH values of the well water samples at sampling distances of 3 and 6 m respectively from the sanitary pits were below the WHO recommended threshold limits for safe drinking water. Additionally, the mean values of turbidity and total dissolved solids of the well water samples at a sampling distance of 3 m from the sanitary pits were above the WHO permissible limits. The pH, turbidity and total dissolved solids are some of the most important parameters used in assessing the quality of any water source, therefore, the poor physicochemical properties of well water samples at a sampling distance of 3 m from the sanitary pits could put at severe health risk consumption of this water over a prolonged time. Siting well water at a reasonable far distance (above 10 m) for sanitary pits especially in communities with severe water scarcity would definitely help guarantee access to safe drinking water by rural as well as urban dwellers in Nigeria.

Enfocus Pitstop Professional 7：预检报告升级

Enfocus将在IPEX2006展会上预展它的Pitstop Professional 7。这是该公司最畅销的Pitstop Professional软件的最新版本，具有极高的生产力和实用性。Pitstop Professional 7的推出标志着Enfocus公司完成了将其所有程序并入Pitstop系列软件的过程。

Overburden management in open pits: options and limits in large limestone quarries

The management of overburden is an important task in open pit exploitations. Site topography and morphology as well as geological and geotechnical properties of natural and remoulded materials are the most important factors affecting the disposal phase. Economic and environmental requirements must be followed in order to achieve the best reclamation results, keeping into account site constraints such as slope stability, hauling and dumping issues, and interactions with groundwater. This paper deals with the above mentioned issues, illustrating a rational approach applied on the case of a large limestone quarry where the thickness of the overburden is relevant and the spoil material has to be dumped in a flooded pit. The proposed multidisciplinary approach led to the selection of most suitable methods for excavation, transportation and disposal. The selection was based on a detailed laboratory and site characterisation that defined favorable and adverse factors to be considered during the preliminary study of a large quarrying project.

Observation of etch pits in Fe-36wt%Ni Invar alloy

To indirectly investigate the dislocation behavior of Fe-36wt%Ni Invar alloy by the etch pit method, polished Invar specimens were etched by a solution containing 4 g copper sulfate, 20 mL hydrochloric acid, and 20 mL deionized water for 2 min. Etch pits in the etched surfaces were observed. All the etch pits in one specific grain exhibited similar shapes, which are closely related to the grain orienta-tions. These etch pits were characterized as dislocation etch pits. It was observed that etch pits arranged along grain boundaries, gathered at grain tips and strip-like etch pit clusters passed through a number of grains in the pure Invar specimens. After the addition of a small amount of alloying elements, the identification of a single dislocation etch pit is challenging compared with the pure Invar alloy. Thus, the observation of etch pits facilitates the investigation on the dislocation behavior of the pure Invar alloy. In addition, alloying elements may affect the densities and sizes of etch pits.

Settlement Prediction for Buildings Surrounding Foundation Pits Based on a Stationary Auto-regression Model

To ensure the safety of buildings surrounding foundation pits, a study was made on a settlement monitoring and trend prediction method. A statistical testing method for analyzing the stability of a settlement monitoring datum has been discussed. According to a comprehensive survey, data of 16 stages at operating control point, were verified by a standard t test to determine the stability of the operating control point. A stationary auto-regression model, AR(p), used for the observation point settlement prediction has been investigated. Given the 16 stages of the settlement data at an observation point, the applicability of this model was analyzed. Settlement of last four stages was predicted using the stationary auto-regression model AR (1); the maximum difference between predicted and measured values was 0.6 mm, indicating good prediction results of the model. Hence, this model can be applied to settlement predictions for buildings surrounding foundation pits.

Environmental records of snow pits in Yuzhufeng Glacier and Xiao Dongkemadi Glacier in the Tibetan Plateau

The contents and distribution characteristics of ions, n-alkanes, and polycyclic aromatic hydrocarbons in snow pits on the Yuzhufcng （YZF） Glacier and the Xiao Dongkernadi （XDKMD） Glacier are studied. Parameter characteristics and correlation coefficients between ions and two organic compounds are used to explore the possible sources of these chemical compositions. The results indicated that both glaciers are influenced by west wind circulation, but the contents of ions, n-alkanes, and polycyclic aromatic hydrocarbons in the YZF Glacier are higher than in the XDKMD Glacier because of differences in geographical position. The ratios of ∑nC21^-/∑nC22^＋ and CPI values （CPI： carbon preference index） indicate that the n-alkanes from natural sources in these two glaciers are mainly derived from higher plants, whereas the contribution from lower organisms was small, also, n-alkanes from anthropogenic sources in the YZF Glacier are higher than in the XDKMD Glacier. The ratios of LPAHs/HPAHs and （Fly＋Pyr）/（BghiP＋INP） indicate that the polycyclic aromatic hydrocarbons in these two glaciers are mainly derived from low temperature combustion of coal and biomass, and, in the XDKMD Glacier, partially from the vehicle exhaust.

Role of Pits in Corrosion Fatigue of Offshore Structural Steel

From the corrosion fatigue test under intermit- tent wetting condition for offshore structural steel of A537 cl.l and data analysis,some results associ- ated with the role of pits in fatigue process have been discussed.

Determination of the Stable Slope Configuration of Oval-Shaped Furrow Pits

The space effects of oval-shaped furrow pit slopes were analyzed by the elastic mechanics principle.The interaction of limit equilibrium slope angle,friction coefficient,cohesion and horizontal radius of oval-shaped furrow pits has been derived.The oval trumpet-like rock mass is homogeneous and elastic while only loaded by its dead weight.The interaction indicates that the deeper an oval-shaped furrow pit is excavated,the greater the limit equilibrium slope angle.Both the theory base for reducing stripping waste rock in an oval-shaped furrow pit and the basic way to determine the configuration of a stable slope were developed from the mentioned interaction.The theory includes the preceding principles of stability analysis of slopes.Compared with the configuration determined by traditional theory of slope stability,a great quantity of stripping waste rock can be reduced by that determined in this paper under stable conditions.

Neonatal pre-auricular pits/sinuses: Survey of management strategies by pediatric otolaryngologists

Background: Neonatal preauricular pit/sinus is a benign embryologic remnant of the first or second branchial arches. The estimated incidence in the US is 1 to 9/1000 newborns, higher in East Asian babies. Most remain asymptomatic throughout life. Inflammatory complications include discharge of squamous debris, cellulitis, or frank abscess. The purpose of this study was to survey pediatric otolaryngologists in the United States and Canada about management strategies for asymptomatic and symptomatic preauricular pits/sinuses. Study Design: A 15-item structured questionnaire covering questions on demographics, professional experience, and medical and surgical management of congenital preauricular pits/sinuses were sent by e-mail and selectively by regular mail to 273 members of the American Society of Pediatric Otolaryngology. Results: 175 of 273 responses (64%) were evaluable. 85% of respondents would simply observe cases of asymptomatic preauricular pit/sinus. Regarding further evaluation, 122 respondents (70%) would not recommend anything other than routine neonatal hearing screen, without need for repeat hearing tests in the first two years of life;34 (19%) would also get BAER hearing test and a renal ultrasound. If a sinus drains sebaceous material intermittently, 65% of the surveyed pediatric otolaryngologists would recommend excision. Ninety nine percent of pediatric ENT respondents would excise a recurrently infected preauricular sinus. Conclusion: Watchful waiting, without requirement of periodic hearing tests in the first 24 months of life is certainly acceptable for management of neonatal asymptomatic preauricular pit/sinus. There is universal agreement that recurrently infected preauricular sinuses should be referred to a pediatric otolaryngologist for surgical excision of the fistulous tract.

Pits and adatoms at the interface of 1-ML C_(84)/Ag(111)

We prepare a well-defined C84 monolayer on the surface of Ag （111） and study the geometric structure by scanning tunneling microscopy （STM）. The C84 molecules form a nearly close-packed incommensurate R30° lattice. The lattice is long-distance ordered with numerous local disorders. The monolayer exhibits complex bright/dim contrast; the largest height difference between the molecules can be greater than 0.4 nm. Annealing the monolayer at 380 ℃ can desorb part of the molecules, but more than sixty percent molecules stay on the Ag （111） surface even after the sample has been annealed at 650 ℃. Our analyses reveal that the 7-atom pits form beneath many molecules. Some other molecules sit at the 1-atom pits. Ag adatoms （those removed substrate atoms, accompanying the pit formation） play a very important role in this system. The adatoms can either stabilize or destabilize the monolayer, depending on the distribution manner of the adatoms at the interface. The distribution manner is determined by the co-play of the following factors： the dimension of the interstitial regions of the C84 overlayer, the number of the adatoms, and the long-distance migration of part adatoms.