有關於平面上"凸集分割的最適長度假說"的進展

Experimental and discrete element methods were used to investigate the effects of distance between two preexisting cracks, bridge area (The length of the bridge area) and its angularities on the shear behaviour of bridge area. A punchthrough shear test was used to model the gypsum (concrete like) cracks under shear loading. Gypsum samples (concrete like) with dimension of 120 mm × 120 mm × 50 mm were prepared in the laboratory. Within the specimen model and near its four corners, four vertical notches were provided. Three different configuration systems were prepared for notches; i.e., paralell and in plane, inside echelon and outside echelon configuration systems, respectively. In these configurations, the length of cracks were taken as 2 cm, 4 cm and 6 cm based on the cracks configuration systems. Then, 9 specimens with different lengths of the bridge area and bridge area angles were prepared. Assuming a plane strain condition, special rectangular models were prepared with dimensions of 100 mm × 100 mm. similar to those for cracks configuration systems in the experimental tests i.e., 9 models with different lengths of the bridge area and bridge area angularities were prepared. The axial load was applied to the punch through the central portion of the model. This testing showed that the failure process was mostly governed by the lengths of the bridge area and bridge area angularities. The shear strengths of the specimens were related to the fracture pattern and failure mechanism of the discontinuities. It was shown that the shear behaviour of discontinuities is related to the number of the induced tensile cracks which are increased by increasing the lengths of the bridge area. The strength of samples decreases by increasing the crack length. Also, the outside echelon crack configuration system has the maximum value of strength while the inside echelon crack configuration system has the minimum value of specimen's tensile strength. The failure pattern and failure strength are similar in both methods i.e., the experimental testing and the numerical simulation methods.

The classroom action research was carried out in order to : (1) make students easier in understanding geometrical formulas; (2) raise the students’ achievement about geometrical formula understanding and its application especially in the case of plane area. : (3) motivate the students to understand geometrical formulas; and (4) make the teaching-learning of understanding geometrical formulas would be more effective. The research was carried out at the fith grade of state elementary school called Terbantaman II in Depok Sleman Yogyakarta. The Research was carried out in three cycles with each sycle consisting of planning, actuating , observing and reflecting. The research data were collected by instruments namely the achievement test, observation and interview. Quantitative data were analysed by descriptive statistics; that was by searching for the mean and by a test of difference, where as qualitative data were analysed by an interpretative descriptive. The research finding showed that the teaching of the plane area formulas of rectangulars and triangles by realistic approach could raise the students’ eagerness and motivation in learning , understanding as well as applying the plane area. It could be concluded that the teaching method applied could raise students’ achievement in learning the plane area formula especially rectangulars and triangels. In othe words, the teaching of geometrical formulas by realistic approach could raise the students’ understanding about geometrical formulas. Key words: Understanding geometrical formulas, realistic approach, and the elementary school.

The area of parameterized approximation seeks to combine approximation and parameterized algorithms to obtain, e.g., (1+epsilon)-approximations in f(k,epsilon)n^O(1) time where k is some parameter of the input. The goal is to overcome lower bounds from either of the areas. We obtain the following results on parameterized approximability: - In the maximum independent set of rectangles problem (MISR) we are given a collection of n axis parallel rectangles in the plane. Our goal is to select a maximum-cardinality subset of pairwise non-overlapping rectangles. This problem is NP-hard and also W[1]-hard [Marx, ESA'05]. The best-known polynomial-time approximation factor is O(log log n) [Chalermsook and Chuzhoy, SODA'09] and it admits a QPTAS [Adamaszek and Wiese, FOCS'13; Chuzhoy and Ene, FOCS'16]. Here we present a parameterized approximation scheme (PAS) for MISR, i.e. an algorithm that, for any given constant epsilon>0 and integer k>0, in time f(k,epsilon)n^g(epsilon), either outputs a solution of size at least k/(1+epsilon), or declares that the optimum solution has size less than k. - In the (2-dimensional) geometric knapsack problem (2DK) we are given an axis-aligned square knapsack and a collection of axis-aligned rectangles in the plane (items). Our goal is to translate a maximum cardinality subset of items into the knapsack so that the selected items do not overlap. In the version of 2DK with rotations (2DKR), we are allowed to rotate items by 90 degrees. Both variants are NP-hard, and the best-known polynomial-time approximation factor is 2+epsilon [Jansen and Zhang, SODA'04]. These problems admit a QPTAS for polynomially bounded item sizes [Adamaszek and Wiese, SODA'15]. We show that both variants are W[1]-hard. Furthermore, we present a PAS for 2DKR. For all considered problems, getting time f(k,epsilon)n^O(1), rather than f(k,epsilon)n^g(epsilon), would give FPT time f'(k)n^O(1) exact algorithms by setting epsilon=1/(k+1), contradicting W[1]-hardness. Instead, for each fixed epsilon>0, our PASs give (1+epsilon)-approximate solutions in FPT time. For both MISR and 2DKR our techniques also give rise to preprocessing algorithms that take n^g(epsilon) time and return a subset of at most k^g(epsilon) rectangles/items that contains a solution of size at least k/(1+epsilon) if a solution of size k exists. This is a special case of the recently introduced notion of a polynomial-size approximate kernelization scheme [Lokshtanov et al., STOC'17].

Reinforcing cement-based materials by nanomaterials has attracted extensive attention over the past decades. It has been reported that the mechanical properties of cement-based materials can be greatly improved by incorporating a small amount of nanomaterials. However, experimental and theoretical works have all focused on the enhancement of cement-based materials subjected to static loading. To the author’s knowledge, no studies have reported on the mechanical properties of nanomaterial- reinforced cement-based composites under high strain rate loadings. This study investigates the reinforcing effect of graphene oxide (GO) on cement mortar under high strain loadings. GO is an emerging nano-scale candidate for enhancing cement-based materials, which is valued for its two-dimensional geometry, superior mechanical properties and large surface area. Tensile splitting and compression tests were conducted on GO-reinforced cement mortar under both static and high strain rate loadings. The high strain rate testing was performed using a Split Hopkinson Pressure Bar (SHPB) apparatus. Static experiments showed that incorporation of GO (of 0.02 wt% of cement) improved the tensile splitting and compression strength of plain cement mortar by 8.9% and 10.8%, respectively, and there was little difference between the 0.02 wt% and 0.04 wt% GO addition. The SHPB tests showed that the reinforcing effect of GO under high strain rate is directly related to the number of cracks. In tensile splitting tests, because the major crack is always localized in the centre of the specimen regardless of the strain rate, the reinforcing effects of GO on cement mortar were the same for different strain rates. In compression tests, however, because the cracks were diffused and there were more cracks under high strain rates, the reinforcing effect of GO was also more significant under higher strain rates. To understand the reinforcing mechanisms of the nanomaterials, the key is to determine the interaction properties between the nano-scale reinforcements and the cement matrix. However, understanding of the governing forces in the reinforcement’s pull-out behaviour at such a small scale is still very limited. The present study is the first to identify the governing force during the pull-out of atomically thin two dimensional (2D) nanosheets (e.g. graphene and its derivative GO) and to develop corresponding theoretical models. In molecular dynamic (MD) simulations, friction was found to make negligible contribution to the pull-out force because of the lack of asperities on atomically thin materials (ATM). The pull-out force was revealed to be governed by a “crack plane adhesion”. Unlike frictional pull-out, crack plane adhesion produces a pull-out force independent of the embedded length of ATM. The magnitude of pull-out force and its affecting factors were investigated by MD simulations. On the basis of crack plane adhesion, the relations between the pull-out force and the pull-out displacement for ATMs was formulated. Furthermore, a new theoretical model was developed to predict the crack bridging stress (σB) of 2D ATMs. The magnitude of maximum σB was estimated to be 3MPa for 0.2 wt% of GO in cement matrix, which was used in the finite element simulations as discussed herein. The fundamental theory and new model proposed here serve as theoretical support for understanding and development of ATM-reinforced composite materials. Finite element simulations for static and SHPB compression tests were conducted using a micromechanical model, the microplane model. First, the microplane model was examined by comparative study with the commonly used concrete damaged plasticity model. Then finite element simulation models of static and SHPB compression tests were built in ABAQUS. For simulation of the static test, by including the calculated crack bridging stress into microplane model, the experimental compressive strength of GO-reinforced cement mortar could be accurately simulated, which validated the calculation of the crack bridging stress by the proposed model in Chapter 4 and the effectiveness of the microplane model to simulate the static behaviour of GO-reinforced cement-based composites. For simulation of the SHPB test, the microplane model with a logarithmic relation between the dynamic increase factor (DIF) and the strain rate to account for the strain rate effect worked for the simulations of plain cement mortar samples. However, for simulation of the GO-reinforced mortar samples, the simulation results give a significant underestimation compared with the experimental results under higher strain rates.

The Wireless Mesh Network (WMN) is a cost-effective solution for backbone networks in both metropolitan and rural areas and can be used as temporary broadband access for emergent and tactic purposes. Without the need of wires, WMNs are easy to deploy and reconstruct to satisfy the dynamic needs. The IEEE 802.16 mesh CDS-mode network is a candidate of next-generation WMNs, which provides the “collision-free” property unique to traditional IEEE 802.11 based WMNs. In this dissertation, we propose several schemes for this new network to enhance its scheduling efficiency on the control plane and its QoS support on the data plane. In addition, we also point out the issues of network initialization of this network on random topologies and propose a scheme to solve these issues. The performances of our proposed schemes are evaluated using both analyses and simulations. Our analytical and numerical results show that our proposed schemes can significantly enhance the performance of the IEEE 802.16 mesh CDS-mode network and benefits upper-layer applications.

This paper examines the kinematical characteristics of the collapse-debris flow in red beds. It presents an evaluation method about spatial prediction of the collapse-debris flow in red beds. It takes the Kangsu collapse in red beds as an example. It uses the aerial photography of the unmanned aerial vehicle and the field geological survey, and combines them with the engineering geological elements of the collapse study area. It analyses the formation mechanism and the failure types of the collapse. The research shows that the collapse is the crack-type collapse. The collapse is mainly controlled by the combination of lithology of dangerous rock mass and structural plane of slope body. The hazard mode is given as follows: Firstly, rocks have the different weathering resistance under the conditions of wind and other external forces. Secondly, under the action of freezing and thawing, the rock mass structure is destroyed. Thirdly, when the unloading fracture zone is expanded further, the bottom of dangerous rock mass can be in an empty state. At last, under the action of gravity, the collapse occurs unsteadily and impacts to the slope surface to form debris flow. And the DAN-W model is used to simulate the motion process of the collapse-debris flow. The calculation results show that the duration of the collapse-debris flow movement is about 50 s, the average thickness about accumulation body reaches 2 m and the maximum speed is 11.5 m·s-1. And the longest impact distance is 315 m. The calculated results are in good agreement with the actual situation. It proves that DAN-W model can be used to analyze the dynamic hazard effects of the collapse-debris flow in red beds area. The paper providesareference for the analysis of the formation characteristics and movement effects of similar potential collapse-debris flow hazards in red beds.

An diagnostic imaging apparatus for imaging information changing with time and displaying it in real time, composed of an ultrasonic probe ( 2 ), having piezoelectric elements arranged in an array form that transmit ultrasonic waves to a target object ( 1 ) and acquires a reflection signal from the target object; a body movement measuring unit ( 12 ) that constitutes a two-dimensional ultrasonic image using the reflection signal acquired by the ultrasonic probe, sets, in the image plane, a plurality of measuring areas used for measuring the body movement of the target object, and measures the body movement and deformation amounts in the measuring areas; and an image accumulating (subtracting) unit for accumulating or subtracting images using body movement measured by the body movement measurement unit.

Background and Purpose: Knee osteoarthritis (OA) is characterized by a progressive loss of the articular cartilage, increasing the amount of friction in the joint, resulting in pain and decreases in mobility and function. Additionally, it has been demonstrated that frontal plane lower extremity (LE) malalignment (e.g., varus, valgus) is associated with onset and progression of OA. Previous studies showed that static loading of 50% body weight at the knee results in more cartilage deformation in those with knee OA compared to healthy controls. As walking produces forces in the knee that are 2-3 times body weight, it may result in greater cartilage deformation. The purpose of our study was to compare the acute effects of walking on the femoral cartilage deformation between individuals with and without knee OA and determine whether LE alignment is associated with greater cartilage deformation. Subjects: 10 subjects without OA (5 females and 5 males; 55.0 ± 1.8 yrs; 78.8 ± 14.0 kg; 1.8 ± 0.2 m) and 9 subjects with OA were recruited (4 females and 5 males; 55.6 ± 4.5 yrs; 97.4 ± 15.0 kg; 1.7 ± 0.1 m). Methods: Each subject underwent X-ray and MRI assessment. For X-ray assessment, persons with Kellgren/Lawrence grades 2-3 were assigned to the OA group whereas subjects with grades 0-1 were assigned to the control group. During MRI assessment, 3T, frontal-plane MRI was obtained before and immediately after 30 minutes of treadmill walking at 3-4 mph. LE alignment was obtained by measuring the angle between the long axes of femur and tibia using a goniometer. To obtain cartilage deformation post-walking, the medial and lateral femoral cartilage of the weight-bearing areas were segmented on subjects’ MRI. Cartilage thickness was quantified by computing the perpendicular distance between opposing voxels defining the edges of the femoral cartilage. Cartilage volume was quantified by multiplying the segmented area by slice thickness. Independent t-tests were used to compare cartilage deformation (i.e., percent changes in medial and lateral cartilage thickness/volume) in response to walking between the 2 groups. Pearson correlation coefficients were used to assess the association between cartilage deformation and LE alignment of all subjects. Results: Independent t-tests revealed no significant difference in percent change of cartilage thickness between OA group and control group in medial (p=0.873) or lateral (p=0.688) femur. Additionally, there was no difference in percent change of cartilage volume between the two groups in medial (p=0.159) or lateral (p=0.327) femur. Pearson correlation coefficient analyses revealed a significant correlation between reductions in lateral femoral cartilage thickness and increased knee valgus alignment (p=0.030).

Knowledge of the orientation of horizontal in situ stresses is important to some areas of oil and gas field development plans. Borehole breakouts observed in image logs and drilling-induced fractures are the main parameters for the determination of the stresses’ directions in situ. In this work, the orientations of borehole breakouts were investigated as a function of depth in oil wells A and B in Lali oilfield, in the Southwest of Iran. Borehole breakouts were detected from FMI logs. By the statistical analysis of the borehole breakouts’ orientation in the foregoing two wells, it was found that, while a mean orientation of minimum horizontal stress in well A is NE-SW, the azimuth of breakout in well B is different with a mean azimuth of 312<strong>˚</strong>±10<strong>˚</strong>. The result reveals that the orientation must be different in these two wells due to some geological abnormality. Therefore, accurate and reliable geomechanical analyses are crucial steps toward minimizing the costs of drilling and completion programs and mitigating borehole instability problems.

IntroductionThere is an increasing interest in the role of hyperplastic processes of endometrium in the “implantation window” disturbance and unsuccessful implantation rate. The endometrium represents a barrier to implantation except under appropriate and defined hormonal conditions.There is no doubt that endometrium has an important role for embryo implantation at early stages of development. Successful implantation requires a functionally normal embryo at the blastocyst stage and receptive endometrium, while the communication between them is also vital.Endometrium shows dynamic and cyclic morphological changes throughout the follicular phase and in the secretory phase. The progesterone-driven differentiative changes in the endometrial epithelium lead to the ‘opening’ of the “window of receptivity” for blastocyst implantation. Morphologically, progesterone-dependent apical cellular protrusions known as pinopods (uterodomes) become visible by scanning electron microscopy on 20th–21st days of human menstrual cycle and then are lost.Materials and methodsA total of 180 endometrial specimens from women with simple hyperplasia (I gr.), endometrial polyps (II gr.) and asynchronous endometrium (III gr.) have been examined by scanning electron microscopy. Biopsies were obtained from fundus of the uterus and processed for light and scanning electron microscopy. Tissues for light microscopy were fixed in 1,25% glutardialdehyde, embedded in paraffin, sectioned and stained with hematoxylin and eosin.ResultsIn I group with simple hyperplasia the ratio of glands and stroma is now increased. Most or all of the endometrial glands are more or less cystically dilated and lined by pseudostratified, highly proliferating epithelium with enlarged, elongated, nuclei in scanty, basophilic cytoplasm. Mitoses are frequent in theepithelium.II group shows endometrial polyps with proliferation of stromal cells incorporating a non-neoplastic glandular component. They were pedunculated with a central fibrovascular core which, when visible in the plane of the section, will be a characteristic diagnostic sign.The hyperplastic polyps contained areas of simple hyperplasia without atypia.In the III group morphology of the deficient secretory phase with coordinated true delay was evaluated and there were no significant changes in ciliated cells quality and quantity. We revealed only “implantation window” disturbance as delay in pinopodes formation or absence of uterodomes.Present study revealed isolated pathological changes of ciliated cells and its conjunction with abnormalities in pinopodes formation (“implantation window”) in women with simple hyperplasia (I group) and polyps (II group) in compare to endometrium of III group.DiscussionWe observed that significant increasing of ciliated cells quantity, cilliar hyperplasia and irregular distribution in women with simple hyperplasia of endometrium can cause breaking of embryo implantation (apposition and attachment) even in case of regular pinopodes formation.

Introduction: Uncertainty regarding the diagnostic evaluation, intervention and prognosis always foiuma reality of medical practice and can reach very high levels in situations of multiple chronic morbidity. The uniqueness of each person with multiple morbidity is one of the most difficult and interesting challenges of day-to-day general practice. The approach to this problem, due to complexity and near absence of clinical research and production of evidence requires the use of tools to facilitate clinical reasoning and decision. Concept: A conceptual mapping follows its own methodology, which is similar in different areas. The map of health problems to a patient is a graphical representation in two dimensions. The idea that led to its development came to the authors a few years ago in response to a practical need for day-to-day. Reflected an evolution of the classical approach of linear list of problems, which is a component of the method developed by Lawrence Weed, for a systemic approach that seeks to study and understand the relationships and linkages between the various problems that coexist in the same person. Looking represent two dimensions, in the same plane, different problems and their possible interrelationships. Visa help address more clearly all the different issues each time (or query) can be placed in the care of patients with multiple morbidity. The map serves as an auxiliary cognitive ideas amplifier, enabling a reflective approach and a systemic understanding of the health problems of each person as an alternative to traditional linear model. Discussion: The map is a graphical representation problems containing elements of two-dimensional dynamic representation that aims to support the cognitive process. The main limitations of this method are its length in the query context, and may be used in specific situations more complex as, for example, when making points situation of patients with multiple morbidity and summaries using flowcharts. Like all systems of record omits the emotional dimension and the temporal dimension.

This study aims to: (1) improve students' understanding of the concept of plane figure areas and how to teach the concept in elementary schools, and (2) investigate students' responses to the learning model. This study employed the action research model using the qualitative approach. The qualitative data were analyzed using the interpretative qualitative technique and the quantitative data were analyzed using the descriptive statistics. The research subjects were all students in Class Q of Semester III 011 PGSO UPP II, consisting of 42 students. The learning process using the· constructivism approach through this action research comprised three cycles; the first cycle consisted of one meeting, the second cycle two meetings, and· the third cycle one meeting. In the first cycle, the results were still disappointing; the average score was only 54. In the second cycle the average score was 67 and in the third cycle the average score was 79. Similarly, in the first cycle students' responses and classroom management were still out of control. In the second cycle they were also still beyond expectation. However, in the third cycle stud·ents' responses and enthusiasms were good as expected. The results of the final test at the end of the action were higher than the criteria. In addition, students' learning varieties were good. The learning process employing the constructivism approach can-be used as a learning alternative especially in understanding mathematical ·concepts in elementary schools

Urban soil pollution has become a major concern in megacities around the world. Due to their non-degradable characteristic, toxic metals are among the most notorious pollutants. In this study determination of total and bioavailable fraction of toxic metals Ni, Cu, Cr, Zn, Co, Cd, Pb and Mn, in surface soils of district 16th in Tehran municipality is considered. Furthermore, metals uptake potential of a variety of endemic plants is also investigated. Forty one surface soil samples and eleven composite leaf samples were collected within the study area in winter 2015. Except for Cd and Pb, other toxic metals showed generally lower concentrations in comparison with shale and mean earth crust values. Intensified traffic load within the district may be considered as the main reason for such augmented concentrations. The order of bioavailable fraction from total metal concentrations detected to be as: Zn(2.78%) > Cd(2.71%) > Co(1.92%) > Mn(1.79%) > Cu(1.59%) > Pb(.89%) > Ni(.7%) > Cr(.4%). Concentration of different metals in leaf samples revealed that berry, eucalyptus, plane and acacia are more capable in comparison with others in translocating toxic metals from soil. Paying more attention to pollution removal capability of urban plants may play a key role in sustainable municipal management of megacities like Tehran.

Effects of age on the speed of hyoid bone movement during swallowing

(2001). Solution of a Calculus Problem on Minimal Volume. The American Mathematical Monthly: Vol. 108, No. 3, pp. 217-221.