Sticking Problems Research Articles

Shear-Type Borehole Wall Shifts Induced During Lost Circulations

Summary Borehole wall shifts during lost circulations are studied and parameter studies are conducted for evaluating the magnitude of the shifts under the following typical drilling conditions. slant-crack induced around vertical wells during lost circulations borehole wall shifts induced during the drilling of normal, thrust, and strike-slip fault areas borehole wall shifts induced for an inclined well because of a fracture induced perpendicular to the minimum in-situ stress Parameters varied are the frac size/wellbore size, frac angle, borehole pressure, and σh1,σH2,σv ratio. These analyses are significant for the following reasons: A new fracture model from a borehole is coded using a 3D-dual-boundary element method. This method allows different displacement and stress traction at the two fracture surfaces along a fracture plane around a borehole. Note that other boundary element methods for 3D nonplanar hydraulic fracture problems have been developed by another group, but these methods did not include a borehole (Yamamoto et al. 1999). Minor borehole wall shifts occur with small-scale fluid losses as observed with borehole imagers (Maury and Zurdo 1996). Although these minor shifts do not create drilling problems, the in-situ stresses may be evaluated from the borehole wall shift if the fractured area is identified by acoustic devices. The current model quantifies the relation between these shifts and other parameters (such as the geological properties and frac size and angle). Significant borehole wall shifts occur if a lost circulation is significant and the leakoff plane is inclined with respect to the principal in-situ stress direction. Some stuck pipe problems may be caused by shear type borehole wall shifts rather than by borehole breakouts or differential sticking problems.

Lime Chemical Bridging, Sticking, and Flow Problems Solved

This article reports on a situation at the Mahoning Valley Sanitary District where problems developed with the flow of lime from the concrete bulk storage bins to the main hopper that feeds the lime slurry machines. Large amounts of airborne lime dust developed as a consequence of the operators using a shovel to move the lime, and the plant's vacuum systems were inadequate to deal with the dust. As a result, the operators were experiencing injuries due to this situation. The article describes the installation of a liner in the concrete lime storage bins that allowed the lime to flow smoothly into the hopper opening. Also, a new air‐filtering system was installed to deal with the dust. Morale has increased because operators no longer spend time hoeing and can be given other tasks including working on plant machinery.

Comparison of residual stress measurement in thin films using surface micromachining method

Conductive, dielectric, semiconducting, piezoelectric and ferroelectric thin films are extensively used for MEMS/NEMS applications. One of the important parameters of thin films is residual stress. The residual stress can seriously affect the properties, performance and long-term stability of the films. Excessive compressive or tensile stress results in buckling, cracking, splintering and sticking problems. Stress measurement techniques are therefore essential for both process development and process monitoring. Many suggestions for stress measurement in thin films have been made over the past several decades. This paper is concentrated on the in situ stress measurement using surface micromachining techniques to determine the residual stress. The authors review and compare several types of stress measurement methods including buckling technique, rotating technique, micro strain gauge and long–short beam strain sensor.

PLASTIC YAM AND PLASTIC YAM STICKS – PERSPECTIVES ON INDIGENOUS TECHNICAL KNOWLEDGE AMONG JAMAICAN FARMERS

ABSTRACTYam farming in Jamaica has been one of the few success stories in agriculture since Independence in 1962. Production is entirely dominated by small farmers who have intensified production systems. Over the last decade yam farmers experienced a ‘yam stick problem’ due to the scarcity, poor quality and high prices of yam sticks. This paper focuses on the content and contextualisation of indigenous technical knowledge among yam farmers. The intrinsic dynamic nature of indigenous technical knowledge is revealed by showing how farmers have adapted their cultivation methods and have themselves innovated new ways of staking yams in efforts to solve the yam stick problem. In effect they have had to rely on their own indigenous knowledge base as a source of new ideas. We discuss a series of alternatives to traditional yam staking methods with a large sample of farmers, including both real and hypothetical examples of externally‐induced innovations. Farmers’ responses to these innovations are reported and analysed in the context of Briggs’ recent review of indigenous knowledge and development issues. Our research suggests that farmer innovation is a normal consequence of coping with farming problems. Further, farmers are not intrinsically unresponsive to externally‐induced innovations, which supports the view that ‘Western science’ and indigenous knowledge are not necessarily bipolar and mutually exclusive knowledge systems. We conclude that indigenous technical knowledge can provide a nexus for research in fostering partnerships with farmers, NGOs and planners in their search for sustainable solutions to the yam stick problem and broader aspects of rural development and resource management.

Surface free energy of non-stick coatings deposited using closed field unbalanced magnetron sputter ion plating

Semiconductor IC packaging molding dies require wear resistance, corrosion resistance and non-sticking (with a low surface free energy). The molding releasing capability and performance are directly associated with the surface free energy between the coating and product material. The serious sticking problem reduces productivity and reliability. Depositing TiN, TiMoS, ZrN, CrC, CrN, NiCr, NiCrN, CrTiAlN and CrNiTiAlN coatings using closed field unbalanced magnetron sputter ion plating, and characterizing their surface free energy are the main object in developing a non-stick coating system for semiconductor IC molding tools. The contact angle of water, diiodomethane and ethylene glycol on the coated surfaces were measured at temperature in 20 °C using a Dataphysics OCA-20 contact angle analyzer. The surface free energy of the coatings and their components (dispersion and polar) were calculated using the Owens–Wendt geometric mean approach. The surface roughness was investigated by atomic force microscopy (AFM). The adhesion force of these coatings was measured using direct tensile pull-off test apparatus. The experimental results showed that NiCrN, CrN and NiCrTiAlN coatings outperformed TiN, ZrN, NiCr, CiTiAlN, CrC and TiMoS coatings in terms of non-sticking, and thus have the potential as working layers for injection molding industrial equipment, especially in semiconductor IC packaging molding applications.

A microfluidic protease activity assay based on the detection of fluorescence polarization

This article describes a fluorescence polarization (FP)-based protease assay on a microfluidic device that is compatible with fast and reproducible analyses of protease activities. The optical systems were arranged for simultaneously measuring fluorescence intensities of vertical and horizontal polarization planes, and the binding of tetramethylrhodamine (TMR) labeled-biotin with streptavidin was utilized for optimizing FP detection in continuously flowing solutions within 74-μm wide, 12-μm deep microchannels of a glass chip. In developing off-chip FP-based assays for proteinase K, trypsin, papain and elastase, TMR conjugated-casein protein (TMR-α-casein) was employed as a universal substrate. After optimization of the hydrodynamic flow control to allow complete mixing of TMR-α-casein and short proteolysis time as possible, and of buffer composition to minimize protein sticking problems, the developed assay was transferred to the microfluidic chip by monitoring FP changes of TMR-α-casein in the main microchannel. The results indicate that the proposed device would serve as an integrated microfluidic platform with automated injection of reacting species, diffusion-controlled mixing, reaction and detection for protease activities without the need to separate the products.

Sol-Gel Coatings for High Precision Optical Molds

The demand for high precision molds for the mass production of optical components is increasing. This paper describes a new approach for manufacturing precision optical molds. Firstly, thin ceramic sol-gel ZrO 2-coatings were deposited onto pre-machined steel and nickel alloy molds. These coatings successfully solve the problem of sticking between the glass and the metal molds during high precision hot-pressing of glass lenses. Secondly, diamond machinable wear resistant sol-gel SiO 2-xC y-coatings were deposited onto pre-machined steel molds for injection molding. Mechanical coating properties like hardness, elastic modulus and density were measured as a function of the sol-gel processing parameters.

Corrosion behaviour of different hot rolled steels

The oxidation–corrosion behaviour of hot rolled alloys was examined by electrochemical impedance spectroscopy. The corrosion behaviour of the non-oxidised alloys was first determined in order to have a reference behaviour. Then, each alloy was oxidised for 1 and 3 days at 650 °C in air and its corrosion behaviour was also determined. For all the alloys, Fe 2O 3 was formed at the scale–gas interface. However, the Fe 2O 3 crystallographic structures varied as a function of the alloy composition. Differences in the corrosion behaviour are due to the thickness, the microstructure and the porosity of the scale. The new graphite chromium iron alloy (Hi-Cr + C) have an oxidation–corrosion behaviour close to the indefinite chill double paired (ICDP) one and is therefore thought to be a good candidate to replace the ICPD alloy. In the case of the high speed steel (HSS) alloy, the oxidation–corrosion kinetics are too slow to prevent sticking problems. The Co addition decreases the corrosion–oxidation rates for the non-oxidised and oxidised samples but this effect is limited in time.

Electrothermally Actuated Fabry–PÉrot Tunable Filter With a High Tuning Efficiency

We report on a electrothermally actuated Fabry-Pe/spl acute/rot wavelength tunable filter with a high tuning efficiency by using surface micromachining. To prevent a current flowing through the mirror, a Wheatstone bridge structure is introduced. Because the full wafer is monolithically grown and the electrodes are formed in a single step, the fabrication processes is simple and reproducible. As the current flows through the two parallel thermal actuators, the top mirror moves away from the bottom mirror so that a sticking problem does not occur. The maximum voltage for the 69-nm wavelength tuning by using a 5.2-/spl mu/m-thick filter structure is only 1.7 V and the high tuning efficiency of /spl sim/75 nm/mW is achieved.

Fabrication Process for Surface Micromachine with Small Sticking Problem by Use of Image Reversal Resist as Sacrificial Layer

A new process is developed for a surface micromachine fabrication with a small sticking problem. Electroplated Ni film is used as maicromachine material and a resist for the image reversal process is used as a sacrificial layer. The processes for the image reversal are carried out before making movable structures. The resist is developed after making movable structures. Movable structures are fixed by small resist columns when the development of the sacrificial layer resist is finished. Finally, the small columns are removed by O2 plasma. Cantilevers with long and wide beam are fabricated by the new process. The cantilever with 1000μm length and 100μm width beam can be fabricated without the sticking problem. The mechanical properties of the electroplated Ni film are examined. It is found that the mechanical properties of the electroplated Ni film is almost same as those of a bulk Ni.

Synthesis of Nanocrystalline Nd16Fe76B8 by Mechanical Alloying and Heat Treatment

The synthesis route for Nd 2 Fe 14 B by mechanical alloying (MA) and subsequent heat treatments was investigated. Elemental Nd, Fe and B powders were mechanically alloyed under Ar and two-stage H2/Ar atmospheres, using a high-energy magneto-mill equipped with rare-earth magnets for the controlled movement of 1″ϕ steel balls. Hydrogen was found to solve the sticking problems of alloying elements via the formation and fracturing of brittle Nd-hydride in the process. Neodymium surrounded by H2 rapidly forms Nd 2 H 5 with excess of H content in the beginning of MA, and the product dehydrogenates slightly in the successive milling up to 200 h in Ar. In Ar-atmospheric MA, on the contrary, amorphous state first results, which changes to a nanocrystalline Nd-rich phase. In both cases, part of α-Fe remains unreacted even after prolonged milling. The lowering and broadening of x-ray peaks reveal that nano-crystallization and/or amorphization proceeded in MA of the elemental powders. In subsequent annealing of as-milled powders, Nd 2 Fe 14 B phase starts to form at 500°C and at 700°C in Ar- and H2/Ar-milling, respectively. The Nd-hydride is thought to form passive laminates among the reactants and inhibit Fe-Nd counter-diffusion.

Influence of the structure of polysulphide additives on the shiftability of manual transmissions

AbstractThe shiftability of manual transmissions is known to be strongly affected by the nature of the transmission oil. When conventional sulphur—phosphorus (SP) additives are used in the oil, gear clashing, sticking, and other problems occur. As reported previously, these problems are caused mainly by the polysulphide used in the SP additives. This paper reports on a study of the effect of the structure of the polysulphide's hydrocarbon chain on the synchromesh characteristics. It is found that polysulphides with long hydrocarbon chains have high kinematic friction coefficients and low static friction coefficients. It is also shown that this phenomenon occurs because of the adsorption of the polysulphide on to the copper alloy of which the gear synchroniser ring is made. By using a polysulphide with a long hydrocarbon chain it is possible to develop transmission oils that have superior load‐carrying capacity and better shiftability even when compared with the latest transmission oils that contain metallic detergents.

Composite coating materials for the moulding of diffractive and refractive optical components of inorganic glasses

The application of glass moulding processes to the fabrication of microoptical components is up to now limited by the problem of sticking between the aggressive glass melts and the moulding tools. In order to prevent this problem, the moulding tools must be coated with anti-sticking, high temperature and oxidation resistant coatings. In the present investigation TiAlN/ZrN composite coatings with superlattice structures were deposited onto fused silica and silicon substrates by r.f.-magnetron sputtering. The influence of deposition parameters and of the superlattice period on residual film stress, oxidation behaviour and the behaviour in contact with hot inorganic glasses was investigated. Fused silica and silicon tool-substrates having optically functional structures generated by lithographic techniques were coated and deployed in moulding experiments performed at temperatures of 600 °C and higher. From the experimental investigations it was found that the oxidation resistance and also the behaviour in contact with hot melts of inorganic glasses were dependent on the superlattice period Λ. It could be observed in thermogravimetric analyses, which have been performed in pure oxygen atmosphere, that for a special superlattice period Λopt no oxidation takes place up to 700 °C. Such coatings could be applied in moulding experiments without reduction of the tools performance by sticking or corrosion in contact with the glass melts. Examples for first applications of the coatings in the moulding of components like micro lens arrays and phase grids from high quality optical glasses are presented.

Low temperature nanoimprint lithography using silicon nitride molds

Nanoimprint lithography has been performed at low temperatures using low stress chemical vapour deposited silicon nitride (Si x N y ) as a mold material, with no sticking problems and hence no need for a release agent or surfactant. Imprint temperature, and the effect of quenching have been investigated and it is found that temperatures as low as 50°C can be used successfully for imprint. Imprint profile due to resist overflow at these temperatures is discussed. Low temperature imprint is important for patterning substrates or polymer-based materials that are intolerant to high temperatures. A low temperature process could also be an advantage for alignment when the mold and substrate have different thermal expansion coefficients.

Synthesis of Cr3C2 coatings for tribological applications

PVD coatings such as TiN and CrN have been successfully applied to metal forming industries for their advanced wear resistance. Metal pick-up and sticking problems in certain deep drawing and plastic injection molding processes, however, demand more sophisticated tribological thin films. In this study, we evaluated chromium carbide coatings synthesized by PVD processes for potential applications in forming and molding operations. We deposited Cr3C2 thin films of 3 μm thickness using both cathodic arc evaporation and unbalanced magnetron sputtering to ensure superior adhesion strength at the film–substrate interface. Using X-ray diffraction (XRD), scanning electron microscopy (SEM)/electron desorption spectroscopy (EDS), Vicker's microhardness, and wear tests, we studied the influences of deposition parameters on microstructure and mechanical properties. Our results indicated that Cr3C2 outperforms hard chrome plating and CrN coatings in measures of sliding wear resistance and ease of mold release. We attributed Cr3C2's performance to its process-improved microhardness and low surface energy. In sum, we found Cr3C2 coatings to be highly promising for tribological applications at low-to-medium temperatures.

Problems of the nanoimprinting technique for nanometer scale pattern definition

We have tested nanoimprint lithography, a new and promising technique for nanometer-scale pattern definition. Preliminary experiments reveal that, besides severe sticking and adhesion problems, the problem of material transport is one inherent to this technique. There are clear indications that most of the effects found may be understood in terms of material transport. We performed experiments within a well defined pressure and temperature window which ranged from 60 to 100 bar and from 50 to 90 °C above the glass transition temperature of the poly(methylmethacrylate)-like polymer used. As a result, the quality of imprint is evaluated with respect to full area pattern transfer, based on a qualitative scanning electron microscope investigation of the fully imprinted area of 2 cm × 2 cm patterned with features of different size and shape. Optimum conditions for imprint quality are found around 100 bar and 90 °C above Tg for the specific polymer used. Although material transport will limit nanoimprint performance in general, it is found that periodic patterns and isolated or small area negative stamp relief patterns are most suitable for high quality nanoimprinting.

Application of extremely low viscosity methylcellulose (MC) for pellet film coating.

Pellet film coating has very limited applicability compared with tablet film coating, because of the problem of sticking during fluidized bed operation. We have prepared an extremely low viscosity methylcellulose (MC) (4 mPa.s), and examined its solution and film properties and its suitability for pellet film coating. MC lost its adhesiveness at a relatively high moisture content and pellet film coating could be achieved without agglomeration of the pellets within a reasonable operating time. The coated pellets were covered with a continuous film of MC, and drug release from the coated pellets was as rapid as that from the core. These findings suggest that MC (4 mPa.s) is applicable for pellet film coating in an aqueous system.

New approach to the old problem of muon sticking in µCF

A new approach is presented for evaluation of the muon “sticking probability” to helium in muon-catalyzed fusion reactions. Use of the “sudden approximation” is avoided. The probabilityΩ s of muon sticking to helium in the reaction dtµ → µ4He+n, calculated with the new method, agrees with previous results. Moreover, the energy and angular distributions for the emitted muon, as well as the dependence of ws on the energy radiated during the muon-catalyzed fusion event, have been evaluated.

Quasiclassical description of condensed systems by a complex order parameter

A quasiclassical description of condensed systems is given in terms of a complex order parameter ψ interacting with a gauge field Aμ. The order parameter ψ can relate as to the conserving as to the non-conserving number of corresponding particles. The electromagnetic field as well as the deformation field of the specific type may take a part of the gauge Aμ-field. The phenomenological Lagrangian of the model is constructed in the coordinate representation. The parameters of the Lagrangian are expressed in terms of the medium polarization function. The transition from the given ψ order parameter to the quasiclassical variables, ∣ψ∣2 and ∇S, where ψ = ∣ψ∣eiS, is performed for the general case of the non-conserving particle number. Equations obtained are formally analogous to the Navier-Stokes equation and to the continuity equation. The latter, however, consists of some particle source in the r.h.s. The principal question on the possibility of the description of systems with dissipation in terms of macroscopic ψ-function is raised and positively solved. The transition from the obtained equations for the macroscopic wave function to the hydrodynamical variables is also performed. The first and the second viscosities are expressed in terms of the medium polarization function. It is shown that the inhomogeneous phase (k ≠ 0) is described by anisotropic hydrodynamical equations. The hydrodynamical equations are reduced to more simple equations describing the relaxation of the new order parameters. As an example, the dynamics of the non-conserving order parameter in the homogeneous system, which undergoes the first order phase transition from the metastable state to the stable one, is considered in detail. The question how the weakly non-spherical overcritical germs acquire the spherical shape during their evolution is studied. It is shown that some essentially non-spherical initial configurations have significantly smaller critical size than the spherical ones and they conserve the shape during their growth to the new phase. The static inhomogeneous configurations of the one-axis systems and the configurations of the anisotropic three-dimensional lattices are studied. The dynamics of the first order phase transition to the inhomogeneous condensed state is considered. It is shown that this dynamics is essentially anisotropic. Different initial configurations have the distinct critical sizes and their evolution is characterized by the various velocities. Achieved dynamical description allows to understand the physical picture of the process of the monocrystal and the polycrystal growth. A possible description of the glassing and amorphouzation processes as the phase transitions from the lability region to some heterogenic inhomogeneous (k ≠ 0) state is discussed. The problem of the domain sticking in the polycrystals is considered. The dynamics of the process of the material aging is also discussed in the framework of the given model.

Cognitive Structure and Development in Nonhuman Primates

Contents: Part I:Introduction. Antinucci, The Comparative Approach to the Study of Cognition. F. Antinucci, The Theoretical Framework. Part II:Longitudinal Study of Cognitive Ontogeny: Birth to Stage 4. G. Spinozzi, F. Natale, Early Sensorimotor Development in Gorilla. P. Poti, Early Sensorimotor Development in Macaques. G. Spinozzi, Early Sensorimotor Development in Cebus. F. Antinucci, Systematic Comparison of Early Sensorimotor Development. Part III:Cognitive Domains. F. Natale, Stage 5 Object-Concept. F. Natale, F. Antinucci, Stage 6 Object-Concept and Representation. G. Spinozzi, P. Poti, Causality I: The Support Problem. F. Natale, Causality II: The Stick Problem. Part IV:Structure and Development of Logical Cognition. F. Antinucci, Introduction to the Study of Logic. F. Natale, Patterns of Object Manipulation. G. Spinozzi, Francesco Natale, Classification. P. Poti, F. Antinucci, Logical Operations. J. Langer, Comparison with the Human Child. Part V:Conclusion. F. Antinucci, On the Phylogeny of Human Cognition.