Zero Length Research Articles

CGDS near-bit geosteering drilling system and its first application in Niger

Abstract The Niger project is one of the important exploration and development cooperation projects of China National Petroleum Corporation in West Africa. The Dibeilla N-1 block of Agadem oilfield in Niger faces challenges such as frequent interlayers and susceptibility to encountering faults during drilling. According to the deployment requirements of the plan, the block will be developed using a mixed well network of horizontal and vertical wells, and the upper sand body will need to be developed using horizontal wells. The dogleg angle of the inclined wellbore should be controlled within 2∼4.5 (°)/30m, and the target thickness should be only 3m. Conventional guiding tools represented by MWD(Measurement While Drilling) cannot achieve effective and efficient reservoir identification and trajectory adjustment in thin oil layers due to their zero length of around 10 meters. Therefore, a geological guiding tool that can achieve near drill bit measurement is needed. Therefore, in order to successfully complete the horizontal section drilling and guidance engineering, maximize the drilling encounter rate of high-quality reservoirs, communicate favorable layers to achieve oil reservoir benefit development, it is decided to use CGDS(CNPC Geological Drilling System)near bit geological guidance tool to implement horizontal section drilling. The system is equipped with gamma, resistivity, and engineering parameter measurements at a distance of 3 meters from the drill bit, providing multiple basis for precise directional guidance of the formation. In the Dibeilla N-1 block of Niger, a total of 6 wells were applied, with an average reservoir drilling encounter rate of 85.38% and a mechanical drilling speed of 12.31 m/h. The first application of this system overseas has provided valuable experience for similar domestic work.

Multi-target automatic positioning based on angle and distance parallel measurement

Precisely and efficiently measuring three-dimensional coordinates of key points on large-scale components in the manufacturing process of aircraft and ships is critically essential. This study presents a multi-target automatic positioning method based on rapid angle and distance measurement in parallel. The measurement processes for angles and distances are decoupled and, when executed simultaneously, aims to enhance the measurement efficiency and automation compared with conventional metrology systems. A cooperative target is devised to realize the rotary-laser scanning angle measurement and absolute distance measurement in parallel. The method of multi-target rough positioning based on rotary-laser scanning and then the precise coordinate measurement method introducing absolute distance constraint are detailed. Especially for the distance measurement, we propose a method to determine the internal zero length and compensate for the distance error caused by mirror offset. A real-site experiment is implemented to verify the method's feasibility and demonstrate that the 3D coordinate measurement accuracy is better than 0.17 mm compared with laser tracker.

Numerical-Computational Model for Dynamic Nonlinear Analysis of Frames With Semi-Rigid Connection Considering the Damping Effect

Objective: the scope of this work is to present a numerical-computational model for transient dynamic nonlinear analysis of frames with geometric nonlinearity and semi-rigid connection. Methodology: the equation of motion, which describes the structural dynamical system, is solved by the a-Generalized direct integration method associated with the standard Newton-Raphson method. The structures are discretized through the co-rotational formulation of the Finite Element Method considering the Euler-Bernoulli beam theory. The semi-rigid connection of structural members (beam-column and beam-support) is simulated by a connection element with zero length, which is described in terms of axial, translational and rotational stiffness. Results and conclusion: From the numerical results of three structural systems (bi-fixed beam, L-shaped frame, and single-story frame) obtained with the free Scilab program, it is concluded that the definition of the type of connection is an important factor to be considered in the analysis of frames subjected to dynamic loads. Furthermore, structural damping, which is a measure of energy dissipation, drives the structure from a vibrating state to a resting state. Research implications: Structural Engineering has been designing systems that cannot be analyzed and dimensioned without dynamic effects being considered. lack of knowledge of the levels and characteristics of the dynamic response can lead to system failure during the application of repetitive loading due to accumulation of structural damage. In this sense, the numerical model can represent a valuable engineering tool when it comes to the dynamic analysis of plane metallic structures with geometric nonlinearity.

Tamper Detection Technique for Text Images based on Vowels and Unicode Zero Length Characters

Tamper Detection Technique for Text Images based on Vowels and Unicode Zero Length Characters

Measurement of Adsorption Properties at Different Scales: from Zero Length Column Experiments on Single Pellets to Breakthrough Curves

AbstractThe ZLC technique is a powerful technique for the measurement of diffusion in nanoporous materials using mg quantities of a sample. Questions remain on whether the measured properties are representative of larger samples. A methodology has been developed to carry out single pellet experiments to determine average properties and variability of equilibrium and kinetic properties. To demonstrate the approach, n‐pentane on HISIV3000 extrudates was used as the test system, which was shown to be macropore diffusion controlled. Results on nine pellets provided average values showing a perfect match to breakthrough column experiments with a sample two orders of magnitudes larger.

Size Effect on Diffusion and Catalytic Performance of Mordenite in Dimethyl Ether Carbonylation

The carbonylation of dimethyl ether (DME) to produce methyl acetate (MA) has a promising prospect in industry. Mordenite (MOR) has been widely studied due to its excellent catalytic activity and high MA selectivity; however, its microporous characteristic limits the intracrystalline diffusion that influences the activity and stability. Therefore, it becomes essential to clarify the relationship between catalytic activity and diffusion. In this study, a series of MOR samples with similar Si/Al contents and aspect ratios, but different sizes, were successfully synthesized by adjusting the synthesis parameters (Si/Al contents in gel, aging time, the amount of water, and alkalinity). Based on quantitative analysis of acid properties and catalyst evaluation, both the apparent turnover frequency of MA (TOFMA) and the stability decrease with the increase in particle size. Diffusion parameter measurements and kinetic analysis via zero length column methods show that the intracrystalline diffusion restriction becomes more serious with increasing particle size. The larger the MOR crystals with enhanced mass transfer limitation that undergo lower activity, the higher the selectivity of byproducts, as well as the faster their deactivation.

Novel Plastic Hinge Element for Seismic Performance Assessment of RC Bridge Columns with Lap Splices

This paper presents a nonlinear analysis procedure for evaluating the seismic performance of reinforced concrete (RC) bridge columns with lap splices using a novel plastic hinge element considering shear deformation. To accurately assess the inelastic behavior of RC bridge columns, reliable three-dimensional (3D) constitutive models are required. However, developing a 3D nonlinear material model is difficult and computationally intensive. In this study, to address these issues, a new plastic hinge element considering shear deformation for RC bridge columns is developed. The new plastic hinge element is based on the Timoshenko beam theory and utilizes two-noded zero length element with six degrees of freedom. The finite element model was implemented in a computer program named Reinforced Concrete Analysis in Higher Evaluation System Technology (RCAHEST) developed by the authors. The developed plastic hinge element for seismic performance assessment of RC bridge columns with lap splices was validated through comparison of the numerical and experimental results.

Shell-Core Structure in Commercial Pellets Detected Using the Zero Length Column Technique

Shell-Core Structure in Commercial Pellets Detected Using the Zero Length Column Technique

Considerations when determining Counter-diffusion constants in liquid phase catalytic reactions using the Zero Length column (ZLC) method

The confusion with diffusion: In heterogeneous catalysis often, the catalytic material is housed within a porous support structure. It is important therefore to determine whether this support structure exerts limiting behaviors. In this paper, desorption and diffusion effects are separated under reactions conditions, to provide accurate effective diffusion constants in swelling and gate-opening catalysts. • A Zero Length Column (ZLC) method was developed using liquid chromatography. • Diffusion in porous catalyst pellets as small as 5 mg can be directly characterised. • Reactant counter-diffusion coefficients were determined for the Heck reaction. • Clear differences in diffusion rates for reactants versus non-reactant species. A Zero Length Column (ZLC) method was developed using a liquid chromatographic system to calculate reactant counter-diffusion coefficients in porous, solvent swollen catalytic pellets and gate-opening support materials. Reactant diffusivities within these porous materials were determined at the reaction conditions of 80 °C and 0.3–0.75 mL min −1 . For all materials, molecules of a similar size to the pore apertures, or molecules with strong interactions with the material surfaces, catalysts, were observable by the ZLC method, with both micro and macropore diffusion observed. Differences between Pd(II) and Pd(0) forms of the EnCat30 catalyst were examined to determine the effects of catalytic deactivation. The deactivated catalyst showed iodobenzene macroporous diffusion constants similar to the relatively inert toluene molecules. Finally, pulse field gradient NMR was utilised to compare and validate ZLC diffusion measurements for solvent swollen reaction systems. This study presents much needed novel findings on diffusivity data for liquid phase catalytic systems.

Laccase immobilized on chitosan-polyacrylic acid microspheres as highly efficient biocatalyst for naphthol green B and indigo carmine degradation

Low cost and non-toxic microspheres constituted by different ratios of chitosan (Cs) and polyacrylic acid (PAA) were manufactured as carriers for laccase (Lc). The CsPAA microspheres characterization proved that the PAA content played an important role on the size, surface morphology and rheological properties, and modulated the enzyme immobilization. The immobilization of Lc involved a multi-step procedure in which the 1-ethyl-3-(3-dimethylaminopropyl carbodiimide hydrochloride (EDC) was used as “zero length” crosslinker. The product with the largest active enzyme amount (44.38 mg Lc/g dry support), and the best operational stability profile was 10CsPAALc3. Also, this product contained the lowest PAA concentration and had excellent rheological properties. Moreover, two current hazardous chemicals, indigo carmine (IC) and naphthol green B (NG), were used as model dyes in practical applications. The biocatalytic decomposition of NG and IC was 1.67 and 2.4 times faster for 10CsPAALc3 compared to the free enzyme. The kinetic profile revealed that the immobilized Lc was less prone to substrate, operational and thermal inactivation. For example, the thermal inactivation for 10CsPAALc3 decreased by approximately 25% when dyes were used as substrate and by 11.71% for ABTS, as compared with the free Lc. The recycling test showed that in 5 cycles the immobilized Lc preserves 81% with NG and respectively 72% for IC of initial activity. The results prove that the new immobilized product can be successfully used in indigoid and metal-complex dyes biodegradation.

Enhanced Adsorption and Mass Transfer of Hierarchically Porous Zr-MOF Nanoarchitectures toward Toxic Chemical Removal.

Zirconium-based metal-organic frameworks (Zr-MOFs) have shown tremendous prospects as highly efficient adsorbents against toxic chemicals under ambient conditions. Here, we report for the first time the enhanced toxic chemical adsorption and mass transfer properties of hierarchically porous Zr-MOF nanoarchitectures. A general and scalable sol-gel-based strategy combined with facile ambient pressure drying (APD) was utilized to construct MOF-808, MOF-808-NH2, and UiO-66-NH2 xerogel monoliths, denoted as G808, G808-NH2, and G66-NH2, respectively. The resulting Zr-MOF xerogels demonstrated 3D porous networks assembled by nanocrystal aggregates, with substantially higher mesoporosities than the precipitate analogues. Microbreakthrough tests on powders and tube breakthrough experiments on engineered granules were conducted at different relative humidities to comprehensively evaluate the NO2 adsorption capabilities. The Zr-MOF xerogels showed considerably better NO2 removal abilities than the precipitates, whether intrinsically or under simulated respirator canister/protection filter environment conditions. Multiple physicochemical characterizations were conducted to illuminate the NO2 filtration mechanisms. Analysis on adsorption kinetics and mass transfer patterns in Zr-MOF xerogels was further performed to visualize the underlying structure-activity relationship using the gravimetric uptake and zero length column methods with cyclohexane and acetaldehyde as probes. The results revealed that the synergy of hierarchical porosities and nanosized crystals could effectively expedite the intracrystalline diffusion for the G66-NH2 xerogel as well as alleviate the surface resistance for the G808-NH2 xerogel, which led to accelerated overall adsorption uptake and thus enhanced performance toward toxic chemical removal.

Analysis of CO2 kinetics in Na,Cs-Rho crystals using the zero length column: a case study for slow systems

Experimental measurements of systems with slow gas transport kinetics are generally considered a relatively easier task when compared to the challenges of measurements of very fast systems. On the other hand, when the transport process goes towards time constants of the order of several hours, not only the measurements, but also the analysis and interpretation of the data offer challenges which make the assessment of the correct time constant of the process non trivial. In this work we used the measurements of CO2 diffusion in Na,Cs-Rho crystals, carried out using the zero length column (ZLC) technique, as a case study for the use of the technique for very slow adsorption processes. The system, which has a time constant of the order of 8 h, shows the importance of using the partial loading approach for the determination of an unambiguous time constant from the analysis of the ZLC desorption curves. The traditional analysis is refined by using the nonlinear ZLC model to take into account the isotherm nonlinearity that results in a concentration dependent diffusivity. Finally, the method proposed by Cavalcante is used to confirm the 3-D diffusion path of the system.

Direct measurement of the mass transport coefficient of water in silica-gel using the zero length column technique

In all silica-gel adsorption processes driven by low-grade heat, the kinetics of adsorption of water on silica-gel is very important in order to optimize design and becomes an essential factor in ultra-low grade heat applications. A new approach for the determination of the mass transfer coefficient of water in commercial silica-gel is proposed and demonstrated with measurements on a single particle using the zero length column technique. Under equilibrium conditions the methodology offers the key advantage to acquire equilibrium isotherms with thousands of points in less than one day. This allows to obtain the relationship between vapour concentration and equilibrium adsorbed amount through numerical interpolation. At higher flowrates, the system operates under kinetic control therefore allowing the determination of the mass transfer coefficient. The novel approach calculates all the elements needed to obtain the mass transfer coefficient from the measured signals without the need to use a specific model. Adsorption and desorption experiments were carried out at different flowrates and three different temperatures. The kinetic responses can be used to determine an average mass transfer coefficient, which is consistent with literature values, but a complex behaviour is observed with surface diffusion as the main contribution to the transport process.

General Marginal Regression Models for the Joint Modeling of Event Frequency and Correlated Severities with Applications to Clinical Trials

In many clinical trials, information is collected on both the frequency of event occurrence and the severity of each event. For example, in evaluating a new anti-epileptic medication both the total number of seizures a patient has during the study period as well as the severity (e.g., mild, severe) of each seizure could be measured. In order to arrive at a full picture of drug or treatment performance, one needs to jointly model the number of events and their correlated ordinal severity measures. A separate analysis is not recommended as it is inefficient and can lead to what we define as “zero length bias” in estimates of treatment effect on severity. This paper proposes a general, likelihood based, marginal regression model for jointly modeling the number of events and their correlated ordinal severity measures. We describe parameter estimation issues and derive the Fisher information matrix for the joint model in order to obtain the asymptotic covariance matrix of the parameter estimates. A limited simulation study is conducted to examine the asymptotic properties of the maximum likelihood estimators. Using this joint model, we propose tests that incorporate information from both the number of events and their correlated ordinal severity measures. The methodology is illustrated with two examples from clinical trials: the first concerning a new drug treatment for epilepsy; the second evaluating the effect of a cholesterol lowering medication on coronary artery disease.

A Scalable Bidimensional Randomization Scheme for TLC 3D NAND Flash Memories.

Data randomization has been a widely adopted Flash Signal Processing technique for reducing or suppressing errors since the inception of mass storage platforms based on planar NAND Flash technology. However, the paradigm change represented by the 3D memory integration concept has complicated the randomization task due to the increased dimensions of the memory array, especially along the bitlines. In this work, we propose an easy to implement, cost effective, and fully scalable with memory dimensions, randomization scheme that guarantees optimal randomization along the wordline and the bitline dimensions. At the same time, we guarantee an upper bound on the maximum length of consecutive ones and zeros along the bitline to improve the memory reliability. Our method has been validated on commercial off-the-shelf TLC 3D NAND Flash memory with respect to the Raw Bit Error Rate metric extracted in different memory working conditions.

Compactification, T-duality and quantum erasers

Using T-duality, we will argue that a zero point length exists in the low-energy effective field theory of string theory on compactified extra dimensions. Furthermore, if we neglect all the oscillator modes, this zero point length would modify low quantum mechanical systems. As this zero length is fixed geometrically, it is important to analyze how it modifies purely quantum mechanical effects. Thus, we will analyze its effects on quantum erasers, because they are based on quantum effects like entanglement. It will be observed that the behavior of these quantum erasers gets modified by this zero point length. As the zero point length is fixed by the radius of compactification, we argue that these results demonstrate a deeper connection between geometry and quantum effects.

Buffered Coordination Modulation as a Means of Controlling Crystal Morphology and Molecular Diffusion in an Anisotropic Metal-Organic Framework.

Significant advances have been made in the synthesis of chemically selective environments within metal-organic frameworks, yet materials development and industrial implementation have been hindered by the inability to predictively control crystallite size and shape. One common strategy to control crystal growth is the inclusion of coordination modulators, which are molecular species designed to compete with the linker for metal coordination during synthesis. However, these modulators can simultaneously alter the pH of the reaction solution, an effect that can also significantly influence crystal morphology. Herein, noncoordinating buffers are used to independently control reaction pH during metal-organic framework synthesis, enabling direct interrogation of the role of the coordinating species on crystal growth. We demonstrate the efficacy of this strategy in the synthesis of low-dispersity single-crystals of the framework Co2(dobdc) (dobdc4-= 2,5-dioxido-1,4-benzenedicarboxylate) in a pH 7-buffered solution using cobalt(II) acetate as the metal source. Density functional theory calculations reveal that acetate competitively binds to Co during crystallization, and by using a series of cobalt(II) salts with carboxylate anions of varying coordination strength, it is possible to control crystal growth along the c-direction. Finally, we use zero length column chromatography to show that crystal morphology has a direct impact on guest diffusional path length for the industrially important hydrocarbon m-xylene. Together, these results provide molecular-level insight into the use of modulators in governing crystallite morphology and a powerful strategy for the control of molecular diffusion rates within metal-organic frameworks.

Accurate blank corrections for zero length column experiments

In this study we present a new methodology for correcting experimental Zero Length Column data, to account for contributions to the measured signal arising from extra-column volumes and the detector. The methodology considers the experimental setup as a series of mixing volumes with diffusive pockets whose contributions to the overall measured signal can be accurately described by simple model functions. The composite effect of the individual contributions is subsequently described through the method of convolution. It is shown that the model parameters are closely related to the physical characteristics of the setup components and as such they remain valid over a range of process conditions. The methodology is firstly validated through fitting to experimental experiments without adsorbent present. The inverse procedure of deconvolution can in turn be applied to experimental data with adsorbent, to yield corrected data which can readily be modelled using standard tools for equilibrium and kinetic analysis. A number of case studies is finally presented exemplifying the effect of applying accurate blank corrections, demonstrating also the application to a nonlinear adsorption system.

Dominant strategy implementability and zero length cycles

Necessary conditions for dominant strategy implementability of an allocation function on a restricted type space are identified when utilities are quasilinear and the set of alternatives is finite. For any one-person mechanism obtained by fixing the other individuals’ types, the geometry of the partition of the type space into subsets that are allocated the same alternative is used to identify situations in which it is necessary for all of the cycle lengths in the corresponding allocation graph to be zero. When all cycle lengths are zero, it is shown that the allocation function can be implemented by setting the payment for an alternative equal to the average length of the arcs that terminate at its node in the allocation graph.

The zero length column technique to measure adsorption equilibrium and kinetics: lessons learnt from 30 years of experience

The zero length column technique has been developed over the past 30 years as a versatile experimental method to measure adsorption equilibrium and kinetics. In this review we discuss in detail the theory that forms the basis for the technique in order to understand how to design and operate efficiently a system. Experimental checks that should be performed to ensure the correct interpretation of the dynamic response are presented and examples are used to identify how to avoid major errors in determining diffusion time constants. The review concludes with an overview of all experimental studies available in the literature to date and a set of recommendations that should help improve the standard in the reported equilibrium and kinetic properties.