The impact of poor cementing casing damage: A numerical simulation study

A good knowledge of the parameters causing casing damage is critically important due to vital role of casing during the life of a well. Cement sheath, which fills in the gap between the casing and wellbore wall, has a profound effect on the resistance of the casing against applied loads. Most of the empirical equations proposed to estimate the collapse resistance of casing ignore the effects of the cement sheath on collapse resistance and rather assume uniform loading on the casing. This paper aims to use numerical modeling to show how a bad cementing job may lead to casing damage. Two separate cases were simulated where the differences between good and bad cementation on casing resistance were studied. In both cases, the same values of stresses were applied at the outer boundary of the models. The results revealed that a good cementing job can provide a perfect sheath against the tangential stress induced by far-field stresses and reduce the chance of casing to be damaged

Investigation of Crack Resistance in Single Walled Carbon Nanotube Reinforced Polymer Composites Based on FEM

Carbon nanotube (CNT) is considered as a new generation of material possessing superior mechanical, thermal and electrical properties. The applications of CNT, especially in composite materials, i.e. carbon nanotube reinforced polymer have received great attention and interest in recent years. To characterize the influence of CNT on the stress intensity factor of nanocomposites, three fracture modes (opening, shearing and tearing) are considered. The stress intensity factor of nanocomposites is evaluated using a representative volume element (RVE) based on the continuum mechanics and finite element method (FEM). Inter-atomic interactions of CNT are simulated by beam elements in the finite element (FE) model. Non-linear springbased line elements are employed to simulate the van der Waals (vdW) bonds. In all fracture modes, the stress intensity factor was determined for pure matrix and matrix reinforced with single-walled carbon nanotube (SWCNT). Numerical results indicate that the load carrying capacities of the CNTs in a matrix are evident. Addition of CNTs in a matrix can increase the stiffness of the composite. Finally, the results showed that utilizing of SWCNT decreased the stress intensity factor and improved crack resistance

Elastic moduli of carbon nanotubes with new geometry based on FEM

In this paper, the elastic moduli of elliptic single walled carbon nanotubes (ESWCNTs) are described. A three-dimensional finite element (FE) model for such carbon nanotubes is proposed. The covalent bonds are simulated by beam elements in the FE model. The elastic moduli of beam elements are ascertained from a linkage between molecular and continuum mechanics. The deformations of the FE model are subsequently used to predict the elastic moduli of ESWCNTs. In order to demonstrate the FE performance, the influence of length, chirality, diameter and cross sectional aspect ratios on the elastic moduli (Young’s modulus and shear modulus) of ESWCNTs is investigated. It is found that the cross sectional aspect ratio of ESWCNTs significantly affects the elastic moduli. With increasing cross sectional aspect ratio, the Young’s modulus and shear modulus decrease. As a result, every change in geometry operates as a defect and decreases the elastic moduli. With increasing the length, Young’s modulus increases and the shear modulus decreases

Exploring the role of R&D collaborations and non-patent IP policies in government technology transfer performance: Evidence from U.S. federal agencies (1999-2016).

Around the world, governments make substantial investments in public sector research and development (R&D) entities and activities to generate major scientific and technical advances that may catalyze long-term economic growth. Institutions ranging from the Chinese Academy of Sciences to the French National Centre for Scientific Research to the Helmholtz Association of German Research Centers conduct basic and applied R&D to create commercially valuable knowledge that supports the innovation goals of their respective government sponsors. Globally, the single largest public sector R&D sponsor is the U.S. federal government. In 2019 alone, the U.S. government allocated over $14.9 billion to federally funded research and development centers (FFRDCs), also known as national labs. However, little is known about how federal agencies' utilization of FFRDCs, their modes of R&D collaboration, and their adoption of non-patent intellectual property (IP) policies (copyright protection and materials transfer agreements) affect agency-level performance in technology transfer. In particular, the lack of standardized metrics for quantitatively evaluating government entities' effectiveness in managing innovation is a critical unresolved issue. We address this issue by conducting exploratory empirical analyses of federal agencies' innovation management activities using both supply-side (filing ratio, transfer rate, and licensing success rate) and demand-side (licensing income and portfolio exclusivity) outcome metrics. We find economically significant effects of external R&D collaborations and non-patent IP policies on the technology transfer performance of 10 major federal executive branch agencies (fiscal years 1999-2016). We discuss the scholarly, managerial, and policy implications for ongoing and future evaluations of technology transfer at federal labs. We offer new insights and guidance on how critical differences in federal agencies' interpretation and implementation of their R&D management practices in pursuit of their respective missions affect their technology transfer performance outcomes. We generalize key findings to address the broader innovation processes of public sector R&D entities worldwide

The Psychometric Properties of Gilliam Autism Rating Scale (GARS)

The purpose of this research was to determaine the psychometric properties of Gilliam Autism Rating Scale (GARS) among Autistic Children and Adolescents in Isfahan. The Statistical population of the study was all Autistic Children and Adolescents (3-18 years), out of which 100 were selected randomly as the statistical sample. Data were collected by administering GARS. Content and face validity of the scale were confirmed by psychology experts. For estimating concurrent validity the correlation between GARS and CARS was 0.80. Its reliability was 0.89 through Chronbach's alpha. The sample was compared with normal children through discriminant analysis. The cut-off point was 52, sensitivity was 99 and specificity was 100 percent. Findings showed that GARS is a valid scale for measuring autism.With regard to its proper validity and reliability, this scale can be used in psychotherapy and research centers. Also, results showed that there was no significant correlation between age and autism symptoms and there was no significant difference between boys and girls in autism symptoms

Electronic control of H⁺ current in a bioprotonic device with Gramicidin A and Alamethicin

In biological systems, intercellular communication is mediated by membrane proteins and ion channels that regulate traffic of ions and small molecules across cell membranes. A bioelectronic device with ion channels that control ionic flow across a supported lipid bilayer (SLB) should therefore be ideal for interfacing with biological systems. Here, we demonstrate a biotic-abiotic bioprotonic device with Pd contacts that regulates proton (H+) flow across an SLB incorporating the ion channels Gramicidin A (gA) and Alamethicin (ALM). We model the device characteristics using the Goldman-Hodgkin-Katz (GHK) solution to the Nernst-Planck equation for transport across the membrane. We derive the permeability for an SLB integrating gA and ALM and demonstrate pH control as a function of applied voltage and membrane permeability. This work opens the door to integrating more complex H+ channels at the Pd contact interface to produce responsive biotic-abiotic devices with increased functionality

Taking electrons out of bioelectronics: Bioprotonic memories, transistors, and enzyme logic

The ability of bioelectronic devices to conduct protons and other ions opens up opportunities to interface with biology. In this research highlight, we report on our recent efforts in bioprotonic devices. These devices monitor and modulate a current of protons with an applied voltage. Voltage-controlled proton flow mimics semiconductor devices with complementary transistors or biological behaviors such as synaptic-like memories and enzyme logic