An Alternative Formulation for Modeling Self-Excited Vibrations of Drillstring with PDC Bits

This work describes an alternative formulation of a system of nonlinear state-dependent delay differential equations (SDDDEs) that governs the coupled axial and torsional vibrations of a 2 DOF drillstring model considering a Polycrystalline Diamond Compact (PDC) bit with realistic cutter layout. Such considerations result in up to 100 state-dependent delays due to the regenerative effect of the drilling process, which renders the computational efficiency of conventional solution strategies unacceptable. The regeneration of the rock surface, associated with the bit motion history, can be described using the bit trajectory function, the evolution of which is governed by a partial differential equation (PDE). Thus the original system of SDDDEs can be replaced by a nonlinear coupled system of a PDE and ordinary differential equations (ODEs). Via the application of the Galerkin method, this system of PDE-ODEs is transformed into a system of coupled ODEs, which can be readily solved. The algorithm is further extended to a linear stability analysis for the bit dynamics. The resulting stability boundaries are verified with time-domain simulations. The reported algorithm could, in principle, be applied to a more realistic drillstring model, which may lead to an in-depth understanding of the mitigation of self-excited vibrations through PDC bit designs.

A Mughal Treatise on Essence and Existence

This article presents an annotated translation of The Equivalence between Giving and Receiving (al-Taswiya bayna al-ifāda wa-l-qabūl), a short Arabic treatise on essence (dhāt) and existence (wujūd) composed by the South Asian philosopher-Sufi Shaykh Muḥibb Allāh Ilāhābādī (996–1058/1587–1648). Although modern scholarship has habitually referred to Muḥibb Allāh as an ardent defender of the doctrine of waḥdat al-wujūd (“unity of existence”) associated with the figure of Ibn al-ʿArabī, such generalized formulations fail to do justice to the uniqueness of Muḥibb Allāh’s intellectual contributions. Most authors who had set out to provide a philosophical defense of Ibn al-ʿArabī’s teachings – including the well-known likes of Ṣadr al-Dīn al-Qūnawī, ʿAfīf al-Dīn al-Tilimsānī, ʿAbd al-Razzāq Kāshānī, Dāwud al-Qayṣarī, ʿAbd al-Raḥmān Jāmī, Mullā Ṣadrā, and so on – had tended to prioritize a philosophically utilizable formulation of wujūd or “existence.” Muḥibb Allāh, in notable contrast, favors a presentation of the divine Reality in terms of “pure essence/quiddity” (dhāt/māhiyya maḥḍa), at times going to considerable lengths to uphold his alternative formulation. Such a strategy of argumentation is uncommon amongst philosophical defenders of Ibn al-ʿArabī, the distinctiveness of which is further enhanced by Muḥibb Allāh’s peculiar mode of disputation, which straddles the line between metaphysics and natural philosophy/physics. The Taswiya occasioned at least sixteen commentaries and refutations; this translation benefits from consulting the earliest of these, composed by Mullā Maḥmūd al-Jawnpūrī (d. 1062/1652) and Khwāja Khwurd (d. 1073/1663), as well as three later commentaries by Ḥabīb Allāh Paṭnaʾī (d. 1140/1728). Most significantly, this translation makes extensive use of Muḥibb Allāh’s own Persian auto-commentary, the Sharḥ-i taswiya, which is a critical aid for deciphering the author’s at times opaque manner of expression and argumentation.

Selective Metal Coordination in Antifouling Coatings

<p>Marine biofouling is the accumulation of biological material (e.g. microorganisms, soft- and hard-fouling organisms) on the surface of an object submerged in seawater, and it remains a worldwide problem for shipping industries. The fouling of ship hulls results in a reduction of speed and manoeuvrability due to frictional drag, as well as increased fuel consumption and accelerated corrosion, and the exorbitant expenses and losses of efficiency attributed to biofouling have prompted the development of antifouling coatings. Current antifouling paints use copper as a biocidal agent, but copper-based paints are increasingly being banned due to environmental concerns about the non-target effects of leached copper. This project aims to circumvent these concerns and tightening regulations via a revolutionary concept: the development of marine antifouling paints that incorporate Cu(II)-selective ligands to draw the biocidal ingredient (i.e. Cu(II)) from seawater. A multistage strategy emerged for the development of this technology. First, criteria were established for the project’s ideal ligand, and ligands were synthesised or selected based on these criteria. Second, the ligands were incorporated in coatings through covalent modification of the paint binder or additives. Third, methodology was developed and implemented to test each coating’s ability to coordinate and retain Cu(II), as well as its subsequent ability to prevent microfouling by marine bacteria. The suitability of two ligand classes was assessed: acylhydrazones and tetraaza macrocycles, specifically cyclen. Unlike the acylhydrazones, cyclen met the established criteria and was initially evaluated as a curing agent and/or surface-modifier in a two-pack epoxy system with resin Epikote™ 235. However, the Cu(II)-loading by these coatings was relatively low, being at most ~0.05% w/w, and the modification of silica, a common paint additive, with cyclen was explored as an alternative formulation route. The method for the functionalisation of silica with cyclen was optimised, and the maximum Cu(II)-loading achieved by the product was 2.60% w/w. The cyclen-functionalised silica was incorporated on the surface of an epoxy coating, and a bacterial adherence assay was developed to assess the cellular attachment of marine bacterium Vibrio harveyi to this coating, which was found to be undeterred. Yet, the development of the strategy and testing methodology by which the project’s goals may be achieved provides a solid foundation for future work.</p>

Selective Metal Coordination in Antifouling Coatings

<p>Marine biofouling is the accumulation of biological material (e.g. microorganisms, soft- and hard-fouling organisms) on the surface of an object submerged in seawater, and it remains a worldwide problem for shipping industries. The fouling of ship hulls results in a reduction of speed and manoeuvrability due to frictional drag, as well as increased fuel consumption and accelerated corrosion, and the exorbitant expenses and losses of efficiency attributed to biofouling have prompted the development of antifouling coatings. Current antifouling paints use copper as a biocidal agent, but copper-based paints are increasingly being banned due to environmental concerns about the non-target effects of leached copper. This project aims to circumvent these concerns and tightening regulations via a revolutionary concept: the development of marine antifouling paints that incorporate Cu(II)-selective ligands to draw the biocidal ingredient (i.e. Cu(II)) from seawater. A multistage strategy emerged for the development of this technology. First, criteria were established for the project’s ideal ligand, and ligands were synthesised or selected based on these criteria. Second, the ligands were incorporated in coatings through covalent modification of the paint binder or additives. Third, methodology was developed and implemented to test each coating’s ability to coordinate and retain Cu(II), as well as its subsequent ability to prevent microfouling by marine bacteria. The suitability of two ligand classes was assessed: acylhydrazones and tetraaza macrocycles, specifically cyclen. Unlike the acylhydrazones, cyclen met the established criteria and was initially evaluated as a curing agent and/or surface-modifier in a two-pack epoxy system with resin Epikote™ 235. However, the Cu(II)-loading by these coatings was relatively low, being at most ~0.05% w/w, and the modification of silica, a common paint additive, with cyclen was explored as an alternative formulation route. The method for the functionalisation of silica with cyclen was optimised, and the maximum Cu(II)-loading achieved by the product was 2.60% w/w. The cyclen-functionalised silica was incorporated on the surface of an epoxy coating, and a bacterial adherence assay was developed to assess the cellular attachment of marine bacterium Vibrio harveyi to this coating, which was found to be undeterred. Yet, the development of the strategy and testing methodology by which the project’s goals may be achieved provides a solid foundation for future work.</p>

Adsorption Inhibitor Role in a Constant Salinity Surfactant-Polymer CSSP Flooding Design for an Offshore Field Application

A base chemical flooding formulation using alkaline-surfactant-polymer (ASP) has been developed for application in offshore environments. The formulation uses combination of conventional alkali (sodium carbonate) with amphoteric surfactant. The field is currently under waterflooding using sea water as injection water. However, since alkali is incompatible with divalent ions in sea water, an alternative formulation using seawater with no additional water treatment is also being developed and considered for application. The alternative formulation uses combination of alkyl propoxy sulfate (APS) and alkyl ethoxy sulfate (AES). Coreflood recovery performance of both formulations is similar. Without alkali, high surfactant adsorption becomes major concern for the alternative formulation. Thus, an adsorption inhibitor (AI) agent – polyacrylic acid type, is being considered as an additive to address this concern. While AI showed potential in reducing surfactant adsorption and improving oil recovery efficiency, it can also increase overall cost for the surfactant in sea water chemical formulation. Hence, the merit to apply AI was not clearly observed.

Simple deformation measures for discrete elastic rods and ribbons

The discrete elastic rod method (Bergou et al. 2008 ACM Trans. Graph . 27 , 63:1–63:12. ( doi:10.1145/1360612.1360662 )) is a numerical method for simulating slender elastic bodies. It works by representing the centreline as a polygonal chain, attaching two perpendicular directors to each segment and defining discrete stretching, bending and twisting deformation measures and a discrete strain energy. Here, we investigate an alternative formulation of this model based on a simpler definition of the discrete deformation measures. Both formulations are equally consistent with the continuous rod model. Simple formulae for the first and second gradients of the discrete deformation measures are derived, making it easy to calculate the Hessian of the discrete strain energy. A few numerical illustrations are given. The approach is also extended to inextensible ribbons described by the Wunderlich model, and both the developability constraint and the dependence of the energy on the strain gradients are handled naturally.

Formulation and evaluation of herbal ointment using leaves of Thuja orientalis l. Leaf extract

The study of diseases and their treatment are important part of our ancient time worldwide. The knowledge of medicinal plants must have been accumulated in the course of many centuries. Herbal plants are huge sources of neutraceuticals, prevent the different disease or maintain healthy life. Plant produces primary metabolites for their basic survival and secondary metabolites for their ecological, taxonomical and biochemical differentiation and diversity. Herbal medicine prepare different part of plant are used. Herbal drug is design as the alternative formulation for the external use in the form of ointment. For the clinical use the herbal ointment apply externally on human body. The main aims of this research are preparation of herbal ointment from the Thuja orientalis L.Plants used as antibacterial activity. Under this research work, it is design as herbal ointment with the help of Ethanolic extract of Thuja orientalis L. and determines the anti bacterial capacity on it. In vitro study the antibacterial activity of the Ethanolic extracts of dried leaves of Thuja orientalis L. are determine by using the Agar cup plate method versus different bacteria such as Staphylococcus aureus, Bacillus subtilis, Escherichia coli and Pseudomonas aeruginosa etc. By blending the Ethanolic extract of Thuja orientalis L.(10 % w/w) into aqueous cream we formulated herbal ointment. The emulsifying agent and simple ointment bases are added in above herbal ointment for increase the antibacterial effectiveness during in vitro evaluation. Thuja orientalis L. (Family Cupressaceae) are broadly used in traditional system of medicine throughout different part of India, China, Russia, Korea, Japan, India, Florida and Iran. It is used in the treatment of diarrhea, cough, cold, bronchitis, and upper part repertory infection. The current study deals with the determination of formulation and evaluation of herbal ointment using Thuja orientalis leave extract.

Probabilistic Storm Surge Estimation for Landfalling Hurricanes: Advancements in Computational Efficiency Using Quasi-Monte Carlo Techniques

During landfalling tropical storms, predictions of the expected storm surge are critical for guiding evacuation and emergency response/preparedness decisions, both at regional and national levels. Forecast errors related to storm track, intensity, and size impact these predictions and, thus, should be explicitly accounted for. The Probabilistic tropical storm Surge (P-Surge) model is the established approach from the National Weather Service (NWS) to achieve this objective. Historical forecast errors are utilized to specify probability distribution functions for different storm features, quantifying, ultimately, the uncertainty in the National Hurricane Center advisories. Surge statistics are estimated by using the predictions across a storm ensemble generated by sampling features from the aforementioned probability distribution functions. P-Surge relies, currently, on a full factorial sampling scheme to create this storm ensemble, combining representative values for each of the storm features. This work investigates an alternative formulation that can be viewed as a seamless extension to the current NHC framework, adopting a quasi-Monte Carlo (QMC) sampling implementation with ultimate goal to reduce the computational burden and provide surge predictions with the same degree of statistical reliability, while using a smaller number of sample storms. The definition of forecast errors adopted here directly follows published NWS practices, while different uncertainty levels are considered in the examined case studies, in order to offer a comprehensive validation. This validation, considering different historical storms, clearly demonstrates the advantages QMC can offer.

Absolute Value Variational Inclusions

In this paper, we consider a new system of absolute value variational inclusions. Some interesting and extensively problems such as absolute value equations, difference of monotone operators, absolute value complementarity problem and hemivariational inequalities as special case. It is shown that variational inclusions are equivalent to the fixed point problems. This alternative formulation is used to study the existence of a solution of the system of absolute value inclusions. New iterative methods are suggested and investigated using the resolvent equations, dynamical system and nonexpansive mappings techniques. Convergence analysis of these methods is investigated under monotonicity. Some special cases are discussed as applications of the main results.

Secure Rate Control and Statistical QoS Provisioning for Cloud-Based IoT Networks

The Internet of Things (IoT) facilitates physical things to detect, interact, and execute activities on-demand, enabling a variety of applications such as smart homes and smart cities. However, it also creates many potential risks related to data security and privacy vulnerabilities on the physical layer of cloud-based Internet of Things (IoT) networks. These can include different types of physical attacks such as interference, eavesdropping, and jamming. As a result, quality-of-service (QoS) provisioning gets difficult for cloud-based IoT. This paper investigates the statistical QoS provisioning of a four-node cloud-based IoT network under security, reliability, and latency constraints by relying on the effective capacity model to offer enhanced QoS for IoT networks. Alice and Bob are legitimate nodes trying to communicate with secrecy in the considered scenario, while an eavesdropper Eve overhears their communication. Meanwhile, a friendly jammer, which emits artificial noise, is used to degrade the wiretap channel. By taking advantage of their multiple antennas, Alice implements transmit antenna selection, while Bob and Eve perform maximum-ratio combining. We further assume that Bob decodes the artificial noise perfectly and thus removes its contribution by implementing perfect successive interference cancellation. A closed-form expression for an alternative formulation of the outage probability, conditioned upon the successful transmission of a message, is obtained by considering adaptive rate allocation in an ON-OFF transmission. The data arriving at Alice’s buffer are modeled by considering four different Markov sources to describe different IoT traffic patterns. Then, the problem of secure throughput maximization is addressed through particle swarm optimization by considering the security, latency, and reliability constraints. Our results evidence the considerable improvements on the delay violation probability by increasing the number of antennas at Bob under strict buffer constraints.