Experimental study on cracking behaviour of moulded gypsum containing two non-parallel overlapping flaws under uniaxial compression

Failure of rock mass that is subjected to compressive loads occurs from initiation, propagation, and linkage of new cracks from preexisting fissures. Our research investigates the cracking behaviour and coalescence process in a brittle material with two non-parallel overlapping flaws using a high-speed camera. The coalescence tensile crack and tensile wing cracks were the first cracks to occur from the preexisting flaws. The initiation stresses of the primary cracks at the two tips of each flaw were simultaneous and decreased with reduced flaw inclination angle. The following types of coalescence cracks were identified between the flaws: primary tensile coalescence crack, tensile crack linkage, shear crack linkage, mixed tensile-shear crack, and indirect crack coalescence. Coalescence through tensile linkage occurred mostly at pre-peak stress. In contrast, coalescence through shear or mixed tensile-shear cracks occurred at higher stress. Overall, this study indicates that the geometry of preexisting flaws affect crack initiation and coalescence behaviour.

Imperfect Emma:An Analysis of Emma's Character Flaws

Emma is the heroine of one of the novels written by Jane Austen(1775-1817) who is among the most widely read writers in English literature.In the novel,also named Emma,Austen portrayed Emma as a young,pretty and smart gentlewoman,yet she was not a perfect or flawless character.She dose not seem to have any sense of her own limitations.Her self-conceit and meddling nature are two of her most fatal character flaws.In this article,we will give a detailed analysis of Emma's flaws supported by various incidents as the novel progresses.We will also find out the two major factors that contribute to develop these character flaws,which are the negative effects caused on her by people very close to her and also the society of her time.

Tragic Flaws of the Protagonists——Hamlet and Gatsby

Hamlet is the most discussed of Shakespeare's tragedies, while The Great Gatsby is the masterpiece of Fitzgerald. It is true that the tragic flaws of the protagonists would be a key factor driving the development of the plots. In these two dramas, the flaws of the protagonists leaded to their tragic endings which are related to their own characteristics of the protagonists. And the ends of the stories are with the tragedies.

Flaws in the Field of Digital Security in the Workplace: Case of Companies in Burkina Faso

Digital in the daily life of companies undeniably leads them to use services and applications of all kinds. Companies in their permanent quest for the exchange of information devote themselves to the use of the Internet which nowadays constitutes an open door for the birth of several types of faults, some of which are unknown to certain digital professionals in the field. Corporate. The purpose of this research is to show the probable existence of digital security flaws in the daily activities carried out by companies in Burkina Faso. In companies in Burkina Faso, we seem to see a way of working that does not respect the standards and safety standards prescribed by ISO 27001. We seem to see a way of working based on the result of the gain and not on the securities measures and integrity of critical data, data confidentiality, management and prevention of possible security risks related to their activities. We seem to be witnessing in companies the immanent presence of faults which could be the work of the users of the system, of the infrastructure used which is outdated or badly configured, of software anomalies linked to programming errors, and to poor implementation of the security policy within the companies. This research is important because it exposes the handicaps that companies have in terms of digital security. The expected result is to bring out existing flaws that are not taken seriously by IT staff and propose possible solutions to overcome these security risks.

An Analysis of the Flaws in the Spanish Tragedy

The Spanish Tragedy, written by Thomas Kyd in the late 1580 s, was the grandfather of all revenge tragedies. It established a new genre named revenge tragedy in English theater. Its well-developed characters, timeless themes, dramatic intrigue and pioneering adoption of blank verse enabled it to be viewed as a classic of London theater. Yet it also has received criticisms over the past centuries. Based on Aristotle's opinion of a perfect tragedy in"Poetics", this paper aims to point out the flaws of the play from five perspectives: the fate of Hieronimo, the cause of it, Bel-imperia's sudden love for Horatio, subplot concerning Villuppo and Alexandro, the discovery and the diction.

Admitting Flaws

In the mid-1980’s researchers at Cleveland State University made a startling discovery. They conducted an experiment by creating two fictitious job candidates—David and John.Thecandidates had identical resumes and letters of reference.The only difference was that John’s letterincluded the sentence“Sometimes,John can be difficult to get along with.”They showed the re-

Image Processing Technology of Flaws within Infrared Transmitting Glasses

We investigated image processing algorithms of the original infrared glass flaw image. Using the Laplacian edge enhancement following LSD （Line Segment Detector） algorithm, we can get a good flaw image very consistent with the original one. This study is very helpful to further enhance the infrared glass flaw inspection technique.

Euler Characteristic Scheme of Globally Searching for Flaws in Surface Modeling

This paper presents a new scheme of flaw searching in surface modeling based on Euler Characteristic. This scheme can be applied to surface construction or reconstruction in computer. It is referred to as Euler Accompanying Test (EAT) algorithm in this paper. Two propositions in algebraic topology are presented, which are the foundation of the EAT algorithm. As the modeling is the first step for rendering in the animation and visualization, or computer-aided design (CAD) in related applications, the flaws can bring some serious problems in the final image or product, such as an artificial sense in animation rendering or a mistaken product in industry. To verify the EAT progressive procedure, a three-dimensional (3D) stamp model is constructed. The modeling process is accompanied by the EAT procedure. The EAT scheme is verified as the flaws in the stamp model are found and modified.

Experimental investigations on the cracking and mechanical responses of PMMA samples with two 3D embedded elliptic flaws under uniaxial compression

In this paper,the cracking and mechanical responses are studied for the Polymethylmethacrylate(PMMA)sample with two three-dimensional embedded coplanar elliptic flaws subjected to uniaxial compression.The experimental results indicate that both the peak stress and crack initiation stress first decrease and then increase with increasing flaw angle,and they increase linearly with increasing flaw spacing.Moreover,five crack modes occur in these tested samples,including the coplanar secondary cracks,wing cracks,petal cracks,anti-wing cracks,and vertical giant cracks.The growth length of wing cracks is approximately equal to the length of the long axis of preexisting flaw.However,the maximum width is roughly equal to half the length of the long axis of pre-existing elliptic flaw.The final failure modes include the splitting failure induced by wing cracks and vertical giant cracks,and the mixed tensile-shear failure induced by coplanar secondary cracks and wing cracks.

The methodology flaws in Hinman's acupuncture clinical trial, Part Ⅰ: Design and results interpretation

In the October 2014 edition of JAMA, Dr. Hinman and her colleagues published an acupuncture clinical trial entitled Acupuncture for Chronic Knee Pain： A Randomized Clinical Trial＂ and concluded that in patients older than 50 years with moderate or severe chronic knee pain, neither laser nor needle acupuncture conferred benefit over sham for pain or function. Our findings do not support acupuncture for these patients[1].

The methodology flaws in Hinman's acupuncture clinical trial, Part Ⅱ: Zelen design and effectiveness dilutions

In the October 2014 publication of JAMA, Dr. Hinman and colleagues published the study “Acupuncture for Chronic Knee Pain： A Randomized Clinical Trial,” which concluded that in patients older than 50 years with moderate or severe chronic knee pain, neither laser nor needle acupuncture conferred benefit over sham for pain or function. Our findings do not support acupuncture for these patients.

Effect of loading direction on interaction of two pre-existing open and closed flaws in a rock-like brittle material

Investigations of the growth,interaction,and coalescence of cracks are important because they help to provide tools for the more realistic modeling of rock masses containing low persistence discontinuities and better estimations of the strength and stiffness of a rock material.Understanding the coalescence mechanism is useful for justifying the mechanism of continental crustal deformation,evaluating the structural failure of slopes with rock bridges,and analyzing the stability of tunnels when a mode I or mix mode failure mechanism is involved.The evaluation of crack growth can provide valuable information about the mechanism for the formation of new geological structures,and the formation,evolution,and growth of faults.This paper reports the results of diametrical compression tests on rocklike disk-shaped specimens.Each specimen contained two pre-existing open or closed flaws.The growth,interaction,and coalescence of the pre-existing flaws were investigated both physically and numerically.A hybrid bonded particle-finite element system was used in the numerical simulation.The results of the physical and numerical studies were in good agreement.In particular,the induced crack patterns showed close agreement in the physical and numerical tests.Digital microscope image processing was used in the physical tests to study the dislocations along the initial flaws.It was shown that wing crack formation was responsible for the failure of the specimen when flaws were inclined with respect to the loading direction.The crack growth and linkage were shown to be affected by the friction between faces of the flaws.In addition,the slip distributions at the flaws surfaces were illustrated and examined to understand the crack propagation mechanism.The effects of the flaws on the disk failure loads were assessed both numerically and experimentally as well.

The methodology flaws in Hinman's acupuncture clinical trial, Part Ⅲ: Sample size calculation

In the October 2014 publication of JAMA,Dr.Hinman and colleagues published the study＂Acupuncture for Chronic Knee Pain：A Randomized Clinical Trial,＂in which the authors concluded that＂in patients older than50 years with moderate or severe chronic knee pain,neither laser nor needle acupuncture conferred benefi t over sham for pain or function.Our fi ndings do not support acupuncture[1]

I-DCGAN and TOPSIS-IFP:A simulation generation model for radiographic flaw detection images in light alloy castings and an algorithm for quality evaluation of generated images

The intelligent detection technology driven by X-ray images and deep learning represents the forefront of advanced techniques and development trends in flaw detection and automated evaluation of light alloy castings.However,the efficacy of deep learning models hinges upon a substantial abundance of flaw samples.The existing research on X-ray image augmentation for flaw detection suffers from shortcomings such as poor diversity of flaw samples and low reliability of quality evaluation.To this end,a novel approach was put forward,which involves the creation of the Interpolation-Deep Convolutional Generative Adversarial Network(I-DCGAN)for flaw detection image generation and a comprehensive evaluation algorithm named TOPSIS-IFP.I-DCGAN enables the generation of high-resolution,diverse simulated images with multiple appearances,achieving an improvement in sample diversity and quality while maintaining a relatively lower computational complexity.TOPSIS-IFP facilitates multi-dimensional quality evaluation,including aspects such as diversity,authenticity,image distribution difference,and image distortion degree.The results indicate that the X-ray radiographic images of magnesium and aluminum alloy castings achieve optimal performance when trained up to the 800th and 600th epochs,respectively.The TOPSIS-IFP value reaches 78.7%and 73.8%similarity to the ideal solution,respectively.Compared to single index evaluation,the TOPSIS-IFP algorithm achieves higher-quality simulated images at the optimal training epoch.This approach successfully mitigates the issue of unreliable quality associated with single index evaluation.The image generation and comprehensive quality evaluation method developed in this paper provides a novel approach for image augmentation in flaw recognition,holding significant importance for enhancing the robustness of subsequent flaw recognition networks.

Fixing Flaws in the Law

China’s top legislature has adopted a draft amendment to the Law on Lawyers that will make it easier for lawyers to meet criminal suspects and obtain evidenceA change to China’s 11-year-old Law on Lawyers is set to empow- er the country’s legal profession. The amendment to the law,which will come into effect on June 1 next year,will allow individuals to open a law firm,improve access to clients and enable lawyers to build a case more easily. Lawyers in China have traditionally lacked power and this has hampered devel- opment of the industry.The amendment could change this and lead to rapid growth in the profession.

Damage evolution and crack propagation in rocks with dual elliptic flaws in compression

To give an insight into the understanding of damage evolution and crack propagation in rocks,a series of uniaxial and biaxial compression numerical tests are carried out.The investigations show that damage evolution occurs firstly in the weak rock,the area around the flaw and the area between the flaw and the neighboring rock layer.Cracks mostly generate as tensile cracks under uniaxial compression and shear cracks under biaxial compression.Crack patterns are classified and divided.The relationship between the accumulated lateral displacement and the short radius（b）is fitted,and the equation of crack path is also established.

Analysis of stress and failure in rock specimens with closed and open flaws on the surface

The influence of closed and open surface flaws on the stress distribution and failure in rock specimens is investigated.Heterogeneous finite element models are developed to simulate the compression tests on flawed rock specimens.The simulated specimens include those with closed flaws and those with open flaws on the surface.Systematic analyses are conducted to investigate the influences of the flaw inclination,friction coefficient and the confining stress on failure behavior.Numerical results show significant differences in the stress,displacement,and failure behavior of the closed and open flaws when they are subjected to pure compression;however,their behaviors under shear and tensile loads are similar.According to the results,when compression is the dominant mode of stress applied to the flaw surface,an open flaw may play a destressing role in the rock and relocate the stress concentration and failure zones.The presented results in this article suggest that failure at the rock surface may be managed in a favorable manner by fabricating open flaws on the rock surface.The insights gained from this research can be helpful in managing failure at the boundaries of rock structures.

Lom： Discovering Logic Flaws Within MongoDB-based Web Applications

Logic flaws within web applications will allow malicious operations to be triggered towards back-end database. Existing approaches to identifying logic flaws of database accesses are strongly tied to structured query language （SQL） statement construction and cannot be applied to the new generation of web applications that use not only structured query language （NoSQL） databases as the storage tier. In this paper, we present Lom, a black-box approach for discovering many categories of logic flaws within MongoDB- based web applications. Our approach introduces a MongoDB operation model to support new features of MongoDB and models the application logic as a mealy finite state machine. During the testing phase, test inputs which emulate state violation attacks are constructed for identifying logic flaws at each application state. We apply Lom to several MongoDB-based web applications and demonstrate its effectiveness.

Mechanical response and microscopic damage mechanism of pre-flawed sandstone subjected to monotonic and multilevel cyclic loading:A laboratory-scale investigation

This study aims to investigate the mechanical response and acoustic emission(AE)characteristic of pre-flawed sandstone under both monotonic and multilevel constant-amplitude cyclic loads.Specifically,we explored how coplanar flaw angle and load type impact the strength and deformation behavior and microscopic damage mechanism.Results indicated that being fluctuated before rising with increasing fissure angle under monotonic loading,the peak strength of the specimen first increased slowly and then steeply under cyclic loading.The effect of multilevel cyclic loading on the mechanical parameters was more significant.For a single fatigue stage,the specimen underwent greater deformation in early cycles,which subsequently stabilized.Similar variation pattern was also reflected by AE count/energy/b-value.Crack behaviors were dominated by the fissure angle and load type and medium-scale crack accounted for 74.83%–86.44%of total crack.Compared with monotonic loading,crack distribution of specimen under cyclic loading was more complicated.Meanwhile,a simple model was proposed to describe the damage evolution of sandstone under cyclic loading.Finally,SEM images revealed that the microstructures at the fracture were mainly composed of intergranular fracture,and percentage of transgranular fracture jumped under cyclic loading due to the rapid release of elastic energy caused by high loading rate.

基于奇异熵的钢球表面缺陷特征提取研究

为评价钢球表面缺陷,应用小波分析、奇异值分解和信息熵相结合的方法提取钢球表面特征,基于奇异熵定义钢球表面图像特征参数,计算4种典型钢球表面缺陷图像的特征参数.结果表明:特征参数能反映图像的纹理特征,钢球表面损伤愈大,纹理愈复杂,其特征参数也愈大,特征参数可用于钢球表面缺陷的识别. Abstract： The character of steel ball surface is extracted to estimate its surface flaws by means of wavelet analysis,singular value decomposition and information entropy. The character parameter of steel ball surface image is defined based on the singular entropy. The character parameters of four typical steel ball surface flaw images are ealculated. It is shown that the character parameter describe the texture character of image, larger surface flaw, more complex surface texture and bigger character parameters. Therefore the character parameters can be used to identify steel ball surface flaws.