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The deep surrounding rock under true triaxial stress is easy to break at the new excavation face, which will induce engineering disasters to threaten personnel and equipment. Many studies h...

In this paper, we build a generalized field-aware factorization machine (GFFM) based on FFM, which stores different feature embeddings in multiple files separately instead of one single file. By making use of the corresponding location relationship between the field index and feature index, GFFM can significantly reduce the computation time. Also, features in GFFM are subdivided into dynamic ones and static ones. When modeling, the temporal variation of dynamic features such as fashion trends and user behavior preferences are considered to establish an accurate dynamic model based on the time window. We further propose DGFFM which uses the wide & deep framework to jointly train GFFM and DenseNet, aiming to combine the benefits of traditional machine learning methods including their faster learning speed on low-rank features and ability to extract high dimensional features. DGFFM add extra first-order identity features into the FM/FFM related models for the first time by adopting the multi-storage pattern designed in this paper. Experimental results on four real-world datasets demonstrate that GFFM can obtain higher accuracy and computational efficiency compared with the state-of-the-art methods used in recommendation and CTR tasks, and DGFFM can achieve an even higher prediction accuracy than recent DNN models.

Ecological resilience is characterized by the recovery capacity of forest ecosystem from a status affected by external disturbance to a stable status, which is one of the important targets for sustainable development of forests. Ecological resilience is sensitive to external factors, such as climate change, forest fire, and silvicutural management at large scales. Understanding the effects of those factors on ecological resilience is important for forest ecosystem management. In this study, we calculated ecological resilience with indicators including forest structure, composition and function. We used a landscape model LANDIS PRO to evaluate the effects of climate change, climate-induced fire, and silvicultural management on ecological resilience in boreal forests. We also evaluated whether the current thinning treatment could be implemented under the scenarios of climate change. The results showed that the initialized stand density and basal area from the year 2000 could represent the real forest landscape in year 2000, with no significant difference between the simulated landscape and the forest inventory data in the year 2010 at landscape scale. The results of simulated fire disturbance were consistent with the results from the field inventories in burned areas. The fire module parameters set adequately represented the current fire regimes in model simulation. The ecological resilience could increase by 15.7%-40.8% at landscape scale when fire intensity increased by 30%, whereas the ecological resilience decreased by 4.4%-24.6% when fire intensity increased by 200%. At the short and medium term, the effects of increased fire on forest ecological resilience were greater than that of climate change. Compared to the current base scenario, forest ecological resilience under B1 climate with fire intensity increased by 30% scenario and A2 climate with fire intensity increased by 200% scenario fluctuated in the ranges of -15.9%-38.9% and -60.4%-34.8% in the whole simulation period at landscape scale. Compared to no harvesting scenario, the current thinning strategy would decrease the ecological resilience at landscape scale under both B1 and A2 scenarios in all simulated periods. Under the scenario of B1 climate with 30% increases of fire intensity, no silvicultural management would be needed in the whole simulation period at landscape scale, whereas medium and high intensity of silvicultural management were suggested under the scenario of A2 climate with 200% increase of fire intensity.生态弹性是森林生态系统在遭受外在扰动后恢复到稳定状态的能力,是森林资源可持续发展的重要目标之一,且森林生态弹性对诸如气候变化、林火和营林措施等外部因子的影响较为敏感.探究这些外部因子对森林生态弹性的影响在未来森林生态系统管理方面有重要意义.本研究首先从森林组成、结构和功能等方面选取指标因子并估算了森林生态弹性值,然后运用LANDIS PRO模型,模拟气候变化、林火干扰和营林措施等对寒温带典型森林生态弹性的影响,并探讨了当前抚育采伐方案在未来气候下的可持续性.结果表明: 模型初始化的2000年林分密度和胸高断面积与2000年真实景观较为吻合,模拟的2010年森林景观与野外调查数据无明显差异,基于当前林火干扰状况的模拟结果与火烧迹地调查数据基本匹配,说明林火模块能很好地模拟当前研究区林火发生状况.林火干扰增加30%将会使该区模拟期内景观水平上森林生态弹性提高15.7%～40.8%,而林火干扰增加200%则会降低该区4.4%～24.6%的森林生态弹性.短期和中期林火干扰增加对森林生态弹性的影响大于气候变化的影响.与当前预案相比,B1气候(林火增加30%预案)和A2气候(林火增加200%预案)对整个模拟阶段景观尺度森林生态弹性的影响分别处于-15.9%～38.9%和-60.4%～34.8%范围内.与无采伐预案相比,B1和A2气候下在整个模拟时期内若继续实施当前抚育采伐方案,将不利于景观水平森林生态弹性的提高.在B1气候(林火增加30%预案)下,在各模拟时期内无需实施任何营林措施;而在A2气候(林火增加200%预案)下,建议实施中、高强度种植的营林措施以提升景观水平森林生态弹性.

In this paper, the shell’s strength and stiffness is calculated according to the theory of elastic mechanics and elastic-plastic mechanics theory.And the analysis of the ANSYS software verify the reliability of the theoretical calculation . Using ANSYS parameter design language (APDL) and the optimized design module of ANSYS,the author studies Material nonlinear static analysis ,and establish the parametric analysis program.

By molecular dynamics method, the tensile processes of nano-single crystal copper with the type I crack under different temperature were simulated, and the effect of different temperature to crack propagation mechanism was analyzed. The results indicate that the temperature has significant effect on crack propagation mechanism of nano-single crystal copper. While the crack is the intrinsic brittle cleavage extension under low temperature and room temperature, the twin crystal is not easily to generate; whereas, dislocation climb caused twin crystal belt appears near the crack tip under high temperature. With load increasing, the length and the width of twin crystals belt increase gradually, and the existence of the twin crystal belt causes the crack branch change to the extending direction.

By FEAt method, the tensile processes of single crystal copper with the type I crack at temperature of 293K were simulated, and the effect of different initial crack lengths to crack propagation mechanism was analyzed. The results indicate that the different initial crack lengths have significant effect on crack propagation mechanism. With the increase of crack length, the critical stress of crack propagation was significantly reduced, the dislocation walls were easy to appear, and mesh staggered of the crack branch along the cleavage plane was more pronounced.

The geological characteristics of coalbed methane from the research carried out in Liupanshui is based on analysis of faults, folds, roof and floor lithology, and depth of coal seam gas content, combined with the assessment of CBM resources calculated through buried depth scope, average coal seam thickness, and gas content, organized by the Ministry of Land and Resources in 2006, which launched the “national new round of coalbed methane re-sources evaluation” project to evaluate the coalbed methane resources in the standard category and divided coal-bed methane resources into I, II and III Category of three resources categories. With this method on the other syncline to resources assessment, the area below 1 000 m is named as I Category resources. And with the depth increasing, resources level decreases.

Based on the field inventory data, the aboveground deadwood debris carbon storage under different fire severities was analyzed in Huzhong forest region of Great Xing' an Mountains. The results showed that the fire severity had a significant effect on aboveground deadwood debris carbon storage. The deadwood debris carbon storage was in the order of high-severitylow-severityunburned in Larix gmelinii stands, and mixed conifer-broadleaf stands ( L. gmelinii and Betula platyphylla), and in the order of high severityunburnedlow-severity in B. platyphylla stands. Fire disturbance significantly changed the component percentage of the deadwood debris carbon storage. The component percentage of snags increased and litter decreased with the increasing fire severity. Logs and stumps did not change significantly with the increasing fire severity. The spatial variation of deadwood debris carbon storage in forests burned with low-severity fire was higher than that in unburned forests. The spatial variation of deadwood debris carbon storage with high-severity fires was lowest. This spatial variation needed to be accounted when calculating forest deadwood debris carbon storage.

In this paper we investigate the consistency problem for spatial relationships in content-based image database systems. We use the mathematically simple matrix representation approach to present an efficient (i.e., polynomial-time) algorithm for consistency checking of spatial relationships in an image. ¶ It is shown that, there exists an efficient algorithm to detect whether, given a set $SR$ of absolute spatial relationships, the maximal set of $SR$ under $\cal R$ contains one pair of contradictory spatial relationships. The time required by it is at most a constant multiple of the time to compute the transitive reduction of a graph or to compute the transitive closure of a graph or to perform Boolean matrix multiplication, and thus is always bounded by time complexity $O(n^{3})$ (and space complexity $O(n^{2})$), where $n $ is the number of all involved objects. As a corollary, this detection algorithm can completely answer whether a given set of three-dimensional absolute spatial relationships is consistent.

Spatial reasoning is an important component in pictorial retrieval systems. There are two approaches to handling spatial relationships: the well-known one is to use algorithms on which most earlier work such as (13, 17, 21) is based, and the recent one (30) is to construct deductive rules that allow spatial relationships to be deduced. Sistla et al. (30) developed a system of rules R on reasoning about basic spatial relationships that are of common interest in pictorial databases. In this paper, we consider the following two problems with that system of rules R: the deduction problem (that is, to deduce new spatial relationships from a given set F of spatial relationships) and the reduction problem (that is, to eliminate redundant spatial relationships from F. We use the mathematically simple matrix representation approach to show that these two prob- lems can be solved by efficient (i.e., polynomial-time) algorithms. The time required by both of them is at most a constant multiple of the time to compute the transitive reduction of a directed graph with n vertices or to compute the transitive closure of a directed graph with n vertices or to perform n × n Boolean matrix multiplication, and thus is always bounded by time complexity O(n 3 ) (and space complexity O(n 2 )), where n is the number of all involved objects.

In this paper we present a very general approach to indexing and retrieval of images in image database systems. We allow dierent ways of indexing and matching for objects in an image, and integrate them with our existing approach of the generalized extended pseudo-2D string and generalized combined 2D string representation of the image to formulate a more general framework for iconic indexing and retrieval of images. Image retrieval is then discussed, and the query processing of image retrieval consists of both matching of objects and matching of spatial relationships. This suggestion for general-purpose image database systems is particularly suitable for building huge, heterogeneous and distributed image databases. 1. Introduction. Image database systems have been very active over the past 20 years. With the explosive interest for the last 10 years in multimedia systems, content-based image retrieval has attracted the attention of researchers across sev- eral disciplines (7), including computer vision, pattern recognition, human-computer interaction, and image databases. Applications that use image databases include oce

An image stored in image database systems is assumed to be associated with some content-based meta-data about that image, that is, information about objects in the image and absolute/relative spatial relationships among them. An image query for such an image database system can generally be handled in two ways: exact picture matching and approximate picture matching. We address the approximate picture matching problem of central interest in this paper, and present a stepwise approximation of intractable spatial constraints in an image query. Especially, this stepwise approximation may be pre-processed on an image query before an advanced picture matching algorithm is invoked. We then work out details of the stepwise approximation algorithm by analyzing, one by one, all possible 16 cases for results of the object matching step. Our analysis turns out that only 13 cases are valid, while the other 3 cases are identified impossible for finding an exact picture-matching between a query picture and a database picture. The worst-case running time complexity is given for each of them. In order to reduce the number of database pictures being matched by a user query, we also provide two suggestions to help enhance the effectiveness of image retrieval at the additional time cost.

This paper was mainly to solve how to accurately and visually simulate the toxic gas diffusion process. ArcGIS Engine drawing methods and key technologies were used, and gas leak emergencies based on Gaussian plume model was selected as a typical scene of emergency evacuation simulation system, dynamic simulation of gas diffusion based on t was implemented, and three key parameters, leakage source strength Q, wind speed V, surface roughness Z0, that affect results of gas diffusion were briefly analyzed and researched. The results show that simulation system can simulate dynamic diffusion processes after leak of toxic gas, and can quickly and accurately draw and calculate regional distribution of equal concentration about three areas at any time after leakage of toxic gas. The results of simulation can have a good assistant decision function on prediction and assessment of toxic gas leakage accident scene.

In this paper we propose a unified iconic indexing, the generalized combined 2D string representation, for images in image databases. Each 2D image is modelled as a generalized extended pseudo-symbolic picture, which has the GEP-2D string representation. We present an efficient algorithm to generate the GEP-2D string representation for each 2D image. We also show how to maintain the complete information about the absolute spatial relationships in the image. Our proposed iconic indexing combines both the GEP-2D string representation and the usual 2D string representation to capture absolute and relative spatial relationships in the image. The result is better representation of spatial relationships in image databases. These results extend our earlier work on a large class of 2D scenes, the extended pseudo-symbolic pictures. Picture retrieval by generalized combined 2D strings is discussed. Our approach can also be easily formulated for 3D images.

A real image is assumed to be associated with some content-based meta-data about that image (i.e., information about objects in the image and spatial relationships among them). Recently Zhang and Yau have addressed the approximate picture matching problem, and have presented a stepwise approximation of intractable spatial constraints in an image query. In particular, in contrast with very few cases done in earlier related works, Zhang-Yau's algorthmic analysis shows that there are all possible 16 cases for results of the object matching step of image retrieval, and 13 out of these 16 cases are valid for the stepwise approximation of spatial constraints while the only other 3 cases are identified impossible for finding an exact picture-matching between a query picture and a databse picture. In this paper, Zhang and Yau have successfully used the stepwise approximation method to work out a simliarity measure between a query image and a database image, for image retrieval. The proposed similiarity measure utlizes the simliarity measures previously developed, by Gudivada and Raghavan (1995) and El-Kwae and Kabuka (1999), for the scenario of the single occurrence of each object in both query and databse images, and extends to cover all 13 valid cases.

In this chapter we describe the generalized combined 2D string representation for images and multimedia documents in visual databases. Each 2D image is modelled as a generalized extended pseudo-symbolic picture (GEP) represented by the GEP-2D string representation. We present an efficient algorithm to generate the GEP-2D string representation for each 2D image. This iconic indexing scheme combines both the GEP-2D string representation and the usual 2D string representation to capture absolute and relative spatial relationships in the image. Application to multimedia document retrieval by generalized combined 2D strings is discussed.

In this paper we model each 2D image as a generalized extended pseudo-symbolic picture based on the absolute spatial relationships in the image. Each generalized extended pseudo-symbolic picture can then be represented by a GEP-2D string. We combine GEP-2D strings and usual 2D strings into generalized combined 2D strings to represent 2D images in order to capture both the absolute and relative spatial relationships in the image. Then we address how to maintain the complete information about the absolute spatial relationships in the image. Picture retrieval by generalized combined 2D strings is discussed.© (1996) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.