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This article explores the links between creative imagination and extraction in the Democratic Republic of the Congo (DRC). This question has an undeniable memorial dimension, for extraction, as a crucial point of entry into Congolese historical consciousness, allows for a multi-perspectivist examination of the way in which the memory of the past has been archived, experienced, and (mis) interpreted. As a key term to understand Congo's geopolitical position since colonial times, extraction offers a rich array of tropes and ideas to assess culture from the DRC and the Congolese diaspora. First, I reflect on the notions of extraction and extractivism; secondly, I analyse how they form the basis of Sammy Baloji's multimedia work in Mémoire (2006) and Mémoire/Kolwezi (2014); then, I turn to La Danse du vilain (2020) and Tram 83 (2014) by Fiston Mwanza Mujila, first to assess how extraction is employed in these novels, then to conduct a reflection on 'necropolitics', and reveal little-known aspects of diamond digging during the Mobutu era. I will also show that Baloji's and Mujila's creative trajectories have been enriched by dialogues with Filip De Boeck, the Belgian social anthropologist and specialist of the DRC. [ABSTRACT FROM AUTHOR]

One must always know the place and accept it as believable. But in most films the design conceit is that when characters are in a place, there is nowhere else they can be found at the moment. This article posits an exception: the 'elevator' plot device, in which every place may be multiplied in layers. Many films of the late 1990s and early 21st century recount a story of dimension-shifting or reality substitution. These 'Elevator films' invoke a connection between discrete spheres sharing a single space or a single moment. A character 'shifts', 'jumps', or 'ports' to a 'higher level', slipping through some highly technologized gateway to the hitherto unlocated. Distinct within the broader category of sci-fi, where travel is generally from one point to another point in this same, single universe, films, such as eXistenZ (1999) and The Matrix (1999) invoke evanescent worlds: a presence and placement unavailable to the waking senses (actual or extended by imagination from the actual). The elevator film suggests that dream domains exist as parts of waking reality, coterminous, and coextensive with the everyday albeit separated by a kind of organizational membrane of definition and containment penetrable through the sacred aperture. [ABSTRACT FROM AUTHOR]

The crown-post roof appeared in England in the second half of the thirteenth century and persisted until the early sixteenth century in the south-east of England. Rafter holes are found in these roofs near to the feet of the rafters on their lower faces. They are blind holes typically 75 mm to 100 mm deep by about 25 mm in diameter. Various theories have been put forward over the years to explain their function. This paper reviews the evidence found on the rafters and integrates it into a revision of one of the earlier theories which suggested that rafter holes formed part of a jig or templet. This jig was used to ensure that the collars were at the correct height relative to the crown plate (or collar purlin). These ideas have been applied in the prefabrication of a new crown-post roof. Evidence is also presented showing how the practice of using jigs to help prefabricate rafter cross-frames may also have been applied to some other roof types such as scissor-braced and side-purlin roofs, in south-east England. [ABSTRACT FROM AUTHOR]

Fine finishing of the inner surfaces of the cylindrical blind holed (CBH) components has a rising demand in the manufacturing industries to reduce their frictional characteristics and improve functional efficiency. So, an attempt has been made in the present work to develop a new magnetorheological finishing (MRF) process with a grinding wheel type single magnetic tool for fine finishing the CBH work part surfaces. The main novelty in the proposed work is the grinding wheel type magnetorheological finishing (GWMRF) tool designed with the V-shaped grooves to retain the magnetorheological polishing fluid more strongly. This is because of the edge effect which provides a higher magnetic flux concentration. Also, the present single GWMRF tool operates eccentrically so that different sizes of CBH surfaces can be finished. After the experimentation with the MRF process using optimized parameters, the roughness values reduce from 240 to 90 nm on the longitudinal and 60 from 230 nm on the flat end surfaces of the CBH workpiece utilizing the V-grooved GWMRF tool. The surface characteristics get enhanced significantly. Thus, the present developed process can find its usefulness in industries for fine finishing the CBH workpieces like molds, dies, etc. after the traditional grinding process. [ABSTRACT FROM AUTHOR]

The central Nigerian Nok Culture is known for its elaborate terracotta figurines and iron metallurgy of the first millennium BC. Since 2005, Goethe University Frankfurt has carried out comprehensive research on this otherwise hardly known cultural complex, focusing on chronology, the structure and function of sites and their reoccupation, environment and subsistence and the function of the enigmatic terracotta figurines. Initial excavations demonstrated that features are scarce and sometimes nearly invisible and that they usually display a mixture of cultural materials of different ages. With an area of 2617 m2, the site of Pangwari represents the largest excavation of the Frankfurt Nok project, geared to tackle the project's key questions. Application of detailed documentation and analysis methods reveals recurring site use between 1500 and 500 BC, a shift in site function and a spatial and temporal relationship between grave features, pits and a terracotta deposition. Canarium schweinfurthii and pearl millet were important constituents of Nok subsistence. Small-scale agriculture probably had only limited impact on the local vegetation, which was a mosaic of dry forests and woodlands. The present synopsis conveys the image of a Nok site, which started as a settlement in the second millennium BC and turned to ritual use around 800 BC. [ABSTRACT FROM AUTHOR]

In this paper, a novel technique has been developed by coupling the conventional finite element method (FEM) with the extended iso-geometric approach (XIGA) for modeling crack growth in engineering materials. The new proposed technique, named as the coupled FE-IGA technique, exploits the advantages of both the FEM and the XIGA. XIGA is used for the approximation of the displacement field in the region surrounding the crack surfaces, whereas the rest of the domain is discretized into conventional Lagrange finite elements. The transition elements are used to connect FEM portion of the domain with the XIGA region. The displacement approximations across the transition elements must preserve the continuity between XIGA and FEM solutions. The Ramp function approach is used for the approximation of the displacement field across the transition elements. The discontinuities such as cracks, holes, inclusions and other material interfaces are modeled independent of the mesh in coupled FE-IGA technique. The standard displacement approximations are enriched with appropriate enrichment functions, which introduce the effect of different discontinuities into the formulation. Finally, several numerical problems are solved by the coupled FE-IGA technique to demonstrate the capabilities of this novel approach in modeling fatigue crack growth in engineering materials. [ABSTRACT FROM AUTHOR]

The article focuses on work of the Portable Antiquities Scheme (PAS) has been highlighted in periodical since 2005. It mentions major functional categories such as currency, trade equipment and household fittings and PAS finds will be discussed in a short note by Alex Bliss. It also mentions small holes are surmounted by a small protruding trefoil.

Cavity volume is an important clinical index for the assessment of the healing process and effectiveness of treatment applied on chronic ulcers. Recently, 3D scanners have proven to effectively track ulcer's volume evolution. However, photogrammetry presents itself as a low cost and portable alternative. We conducted a comparative study between photogrammetric and 3D scanner-based volume estimation of small skin ulcers. A total of 24 cutaneous leishmaniasis ulcers' virtual models were generated using a commercial laser scanner and a full-HD portable camera. The reconstruction from videos was performed using open-source software (VisualSFM). The results revealed a similar performance when compared to 3D Scan-based volume estimation with a median deviation and percentile error of 33.68 mm3 and 21.10%, respectively. In addition, the method proved to effectively follow the same tendency in the assessment of healing ulcers when compared to the 3D-scanner. Moreover, when comparing the two virtual models trough residual differences after ICP registration the mean error and standard deviation was 0.36 ± 0.27 mm. [ABSTRACT FROM AUTHOR]

Space-averaged surface temperature distributions and overall Nusselt number measurements have been carried out to study the transient mixed convection heat transfer in a channel with two facing and symmetrically heated semicircular cavities. Effects of buoyancy, channel orientation, and channel aspect ratio on thermal behavior have been investigated from Re 500 to 1,500. Depending on the parametric set, steady, oscillatory, and irregular thermal regimes have been identified. The natural frequencies and time scales of the oscillatory regimes have been obtained using spectral analysis. Results show that with increase in channel aspect ratio, the heat transfer performance reduces for all inclination angles. [ABSTRACT FROM AUTHOR]

A small bowel prolapse through the vaginal introitus after a transvaginal instrumental gravid uterus perforation is a surgical emergency. To define the mechanisms of an irreversible, small bowel ischaemia due to small bowel prolapse through a vaginal introitus, ClinicalTrials.gov, PubMed, PubMed Central, and Google Scholar were searched. Out of the 81 articles screened, 28 cases of a small bowel evisceration through vaginal introitus were included. A small bowel obstruction severity grading was defined with risk factors; potential mechanisms of different severity grades after a transvaginal instrumental gravid uterine perforation with a vaginal evisceration. The duration of symptoms or a delay in the diagnosis did not change the incidence of the two most severe grades-mesenteric stripping and a small bowel degloving. Both obstruction types develop immediately during an instrumental abortion. The severity of obstruction does not influence the maternal outcome. [ABSTRACT FROM AUTHOR]

An efficient analytical model has been developed for predicting the electromagnetic (EM) field coupling to a lossless transmission line (TL) penetrating through cascaded multiple rectangular enclosure with hybrid apertures (apertures with and without conductive sheets coexist) excited by an external plane wave of oblique incidence. First, The EM field in the enclosure through apertures covered by conductive sheets is derived using the dyadic Green's function and the transfer impedance of the sheet. Then, the EM field in the enclosure through apertures without sheets is derived based on the Bethe's small holes theory and the mirror procedure. Finally, the electric current induced at the TL terminals is obtained combining the equivalent lumped-pi circuit model of the TL and the Agrawal's model. The analytical model has been successfully verified by the finite-difference time-domain (FDTD) method over the frequency range of 0.1 ~ 3 GHz, which consumes less time than numerical methods. [ABSTRACT FROM AUTHOR]

A simple method for estimation of the unloaded quality factor of single and double re-entrant cylindrical cavities was developed based on Wheeler's incremental inductance rule. The proposed approach was benchmarked for a Ka-band re-entrant cavity against 3D electromagnetic simulation using CST Studio and also with measurements. The analysis is general and unlike the approach of Fujisawa, it could be extended to analyze the re-entrant cavity comprising dissimilar materials. The effect of surface roughness on the quality factor of the cavity also could be estimated using the present analysis. [ABSTRACT FROM AUTHOR]

Edge-chipping, surface roughness and dimensional accuracy are crucial quality aspects of drilled holes in hard-to-cut material such as glass, ceramics and carbon fiber reinforced plastics. In this article, an experimental study was conducted to investigate the quality measures of holes produced by rotary ultrasonic drilling (RUD) and conventional drilling. Edge-chipping width at tool exit side, the surface roughness (Ra and Rz), out-of-roundness, cylindricity error and hole conicity were the main responses when drilling soda glass using diamond abrasive tools and a cutting fluid. Statistically designed experiments were carried out for rotary ultrasonic and conventional drilling (CD) at two levels of tool feed rate (0.6 and 6 mm/min), spindle speed (3,000 and 8,000 rpm) and tool particles-concentration. Analysis of variance was used to define the significant factors and their interactions and build models for predicting the responses. The results showed that reducing the chipping, surface roughness and roundness error. The normal tool concentration showed a substantial effect in improving the surface quality and reducing the hole-geometrical errors. [ABSTRACT FROM AUTHOR]

We present a scheme for generating entangled states of two qutrits, by using a 4-level system and a 3-level system coupled to a single cavity. Because of only employing resonant interactions, the entangled state can be fast created. This scheme is easy to implement in experiments since only a single cavity is needed and none of measurement, auxiliary system and identical system-cavity coupling constant is required. Furthermore, two-qutrit partially or maximally entangled states can be created by using this scheme. The proposal is quite general, which can be used to prepare entangled states of two qutrits in various physical systems, such as two natural or artificial atoms of the Λ-type or Δ-type three lowest levels, coupled to an optical or microwave cavity. [ABSTRACT FROM AUTHOR]

In this study, four novel film cooling hole designs, all based on cylindrical holes, are numerically evaluated, and compared with those of a simple cylindrical hole and a laterally-diffused shaped hole. Film cooling effectiveness and surrounding thermal and flow fields are documented for operation with various blowing ratios. It is shown that the two-stage cylindrical hole can improve film cooling effectiveness at higher blowing ratios. The primary hole with two secondary holes can enhance film cooling performance by creating anti-kidney vortex pairs that will weaken jet liftoff caused by the kidney vortex pair that is created by the primary hole. The tri-circular shaped hole provides better film cooling effectiveness values only near the hole, but worse at downstream positions. The two-stage structure for the tri-circular shaped hole provides better film coverage because it changes the flow structure inside the delivery channel and decreases jet penetration into the passage flow. [ABSTRACT FROM AUTHOR]

Orifice spillways are provided in Run-of-the-river diversion dams where management of sediment along with flood is the main issue. However, accommodating the spillway in a narrow gorge with very high discharges is another aspect. Multistage spillways are provided in such cases to overcome the space constraint. Such designs are hydraulically complex as there is interaction of flow at the junction of exit of the lower and upper spillways. Design of these structures cannot be standardised and depend on site-specific conditions. Extensive physical model studies are required for optimising the design. Siang Lower H. E. Project is a run-of-the-river scheme located on Siang River in East Siang district of Arunachal Pradesh. The spillway arrangement envisaged is unique, consists of two-tier spillway comprising overflow ogee spillway on the top tier and sluice spillway in bottom tier. A common energy dissipator in the form of stilling basin has been provided for both overflow and sluice spillways due to high tail water. The present paper describes the hydraulic model studies for Lower Siang H.E. Project, Arunachal Pradesh carried out on 1:55 scale 2-D sectional model for optimising the design of two tier spillway and energy dissipater arrangement. [ABSTRACT FROM AUTHOR]

Orifice spillways have been widely recognized as the most appropriate especially for run-of-the-river projects for handling both flood releases and flushing of sediments. The present paper discusses various important parameters to be considered in the design of an orifice spillway, evolution of orifice spillway, and structural design consideration. A need for physical and numerical model for modeling spillway flows has been identified. Literature review on physical and numerical model studies of orifice spillway has been reported. Central water and power research station has contributed in evolving the design of orifice spillway by conducting hydraulic model studies for more than 25 projects. However, no guidelines have been developed as the data was site-specific for each case. Based on the data, a need for further research is identified and discussed in detail. Roof profile is found to be an important hydraulic parameter as it affects the discharging capacity of the orifice spillway. However, design of roof profile has not been standardized so far. Hence, basic research studies were taken up to develop the design guidelines for roof profile using physical and numerical models. The important findings obtained from the basic research study have also been discussed in the present paper. An equation was developed to design the roof profile, which will be useful for the engineers at the initial stage of design of orifice spillway. [ABSTRACT FROM AUTHOR]

Objectives: Iatrogenic perforations are the most common cause of esophageal perforation. We present our experience mainly based on a non-operative treatment approach as well as long-term outcome in these patients. Materials and methods: Twenty-one patients were treated for iatrogenic esophageal perforation at Oslo University Hospital, Ullevål from February 2007 to March 2014. The etiology of perforation was dilation of benign stricture in eight patients, either dilation, stenting or stent removal in four with malignant stenosis, during diagnostic endoscopy in four, removal of foreign body in two and by other causes in three patients, respectively. After median 82 months, 10 patients alive (47.6%) were sent questionnaires about dysphagia, HRQoL and fatigue. Results: Median age at time of treatment was 66 years. Median in-hospital stay and mortality were 10.5 days and 4.8%, respectively. Initial treatment in 15 patients (71.4%) was non-surgical of whom one needed delayed debridement for pleural empyema. Initial treatment in six patients (28.6%) was surgical of whom three needed delayed stenting. Altogether 14 patients (66.7%) were stented. Eight (57.1%) had restenting. Median number of stents used was 1 (1–4). The stents were removed after median 36 days. The perforations healed after 2.5 months. After median 82 months, the patients reported reduced HRQoL. There was no significant difference regarding level of dysphagia and fatigue. Conclusions: We report satisfactorily short-term and long-term results of iatrogenic esophageal perforations. Mortality was low and HRQoL was deteriorated. Dysphagia and fatigue were comparable to a reference population. [ABSTRACT FROM AUTHOR]

The present work investigates the enhancement of heat transfer rate through staggered pin fins of different shapes with different perforation geometries, namely circular, diamond shaped and elliptical type. Three dimensional computational fluid dynamics simulation has been carried out to analyze the effects of fin geometry and dimension of perforation as well as the shape of fin to enhance heat transfer rate against pressure loss. Results show that the heat transfer rates of perforated fins up to certain perforation number and size are always greater than the solid ones and with the change of fin shape and perforation geometry heat transfer rate also improves significantly. On the other hand pressure drop through heat sink decreases not only with increasing perforation number but also with the size of perforation. Moreover, variation of pressure drop of perforated fins is influenced with fin geometry. [ABSTRACT FROM AUTHOR]

Perforated blockages with inclined impingement holes are one of the cooling methods that can be used in the trailing edge of gas turbine. This method has a high heat transfer enhancement as well as high frictional resistance. Numerical investigation has been conducted to make a deep insight into the flow fields and pressure distribution of this cooling structure. Split of high heat transfer region has been detected in the impingement region, which may enlarge the thermal stress of metal bulk. The pressure gradient and counter rotating vortex is found to be the mainspring of this phenomenon. Large total pressure dissipation is founded within the impingement chambers. [ABSTRACT FROM AUTHOR]

The quantitative identification of multiple internal cavities of one finite body has become a research focus in fields of both thermographic nondestructive testing and inverse heat transfer problem. At present, due to calculational complexities, little progress has been made in the identification of multiple cavities based on surface temperature measurements. In this study, a new method, based on the topology optimization, for the identification of multiple cavities in one finite body is proposed. A multiple measurements combination method is used to eliminate the effect of the low thermal signature of internal cavities on outer boundaries to obtain accurate identification results. By taking a square test-piece with different cavities as examples, the performance of the method is studied systematically. A series of numerical and experimental test cases have certified that the method has a very superior performance even under the influence of various factors. [ABSTRACT FROM AUTHOR]

In the field of engineering, understanding the flow characteristics of an orifice is key to accurately controlling pressure or flow; however, the transitional flow characteristics of the two-stage orifice has not been studied. The value of the discharge coefficient parameterizing the two-stage orifice flow equation is primarily based on that of the single classic orifice; however, this assumption leads to significant errors, because of the different numbers in the sudden contraction structure. Through theoretical derivation, the flow equations difference between the two-stage orifice and single classic orifice was compared and analyzed. Combing theoretical analysis, Computational Fluid Dynamics (CFD) simulation and experimental measurement, the transitional flow characteristics of the twostage orifice were investigated using mineral oil. The comparison results of the three parts are essentially consistent. In this paper, the discharge coefficient and the pressure drop over the twostage orifice were primarily focused on Reynolds numbers between 900 and 1700. In comparison with the single orifice, the results show that under the same dimensions (d = 3 mm), the discharge coefficient of the two-stage orifice is greater, and the transitional flow state of the two-stage orifice is different from that of the single orifice. Additionally, the pressure drop of the two-stage orifice is less than that of the single orifice under the same volume flow rate. The prestage cylindrical hole slows the changing trend of the flow field parameters, and the second-stage orifice with smaller diameter is mainly responsible for the pressure loss. The current research provides important support for accurate pressure and flow control of the two-stage orifice, and the role of the prestage cylindrical hole can also be a good reference in the structure design of micro-orifices. [ABSTRACT FROM AUTHOR]

The aim was to determine the impact of membrane properties and operating conditions upon predicted performance of osmotically driven actuators. An actuator fitted with a forward osmosis membrane was studied, and significantly we examined the reversibility of the actuation process. It was discovered that the actuation-retraction cycle could be repeated for over 60 cycles before salt concentration became similar on both sides of the membrane. The cycle length and number of operative cycles were shown to be a dependent on membrane properties. It was demonstrated that issue of long actuation time can be addressed using membranes with high water permeability. [ABSTRACT FROM AUTHOR]

An investigation of the hole cutting and drilling processes on woven carbon-fiber reinforced polymer sheets using abrasive waterjet (AWJ) is presented. The drilling process uses a stationary AWJ to impinge a target material to make a hole, while the cutting process requires an AWJ to penetrate the workpiece before moving in a circular path to cut a hole. It is found that the holes machined by both the processes exhibit similar geometrical features, where the diameter at the top is greater than at the bottom. It is further found that the holes from the drilling process have a better roundness than those from cutting process primarily due to the jet instability during cutting movement. Plausible trends of the hole characteristics (e.g., diameter and wall inclination) and defects (e.g., delamination) with respect to the process parameters are discussed. It is shown that water pressure is the major parameter affecting hole defects. The hole drilling process yields more severe defects than the cutting process because of the initial impact of the jet. Predictive models for machined hole diameter in both processes are developed. The model predictions are in good agreement with the experimental data under the corresponding conditions. [ABSTRACT FROM AUTHOR]

The present paper investigates low-velocity impact characteristics of AA1100 grade aluminium thin plate under blunt, hemispherical, ogive and conical shape impactors. AA1100 is ductile and therefore can undergo large plastic deformation and subsequent fracture and perforation. The effect of impactor shape on the contact force, absorbed energy dissipation, perforation and failure modes was studied. Johnson-Cook material model was used in numerical simulations with its material constants determined using experimental. The finite element solver ABAQUS/CAE is used to conduct the numerical study. The study is conducted using 2, 4, 6, 10, 14, 16, 18 and 22 J impact energy with velocity ranges 1.15-3.80 m/s. Results show that increase in the nose radius of impactors reduces the perforation time due to increment in contact force. Blunt impactor shows high impact resistance and hemispherical have acquired large energy absorption capacity followed by ogive and conical impactors. [ABSTRACT FROM AUTHOR]

Understanding the progressive failure of laminated composite plays an important role in the structural integrity analysis of a structure. Continuum damage mechanics-based approach is one of the powerful tools to analyze the failure of laminated composite structures. The present paper investigates the damage evolution and progression in laminated composites with a hole under flexural loading. The presence of high-stress concentrations along with the free edge stresses at the vicinity of the hole in laminated composite leads to complex failure mechanisms. The influence of the change in thickness and lamina configuration on the strength characteristics is presented. [ABSTRACT FROM AUTHOR]

Reaming is carried out after twist drilling to enlarge and finish the holes accurately. The experiments were carried out on mild-steel workpieces at different reaming conditions and the accuracy and surface finish values are very briefly compared with the results of earlier investigators. A detailed analysis of the harmonic contents of the axial and transverse profiles of the reamed holes was carried out to bring out the process characteristics. A preliminary study of the cutting forces in reaming based on the spectral analysis is also reported. [ABSTRACT FROM AUTHOR]

Boring Trepanning Association (BTA) drills are capable of machining holes having large length to diameter ratio in a single pass. The study of the accuracy and surface finish of holes produced would reveal quite useful information regarding the process. This paper deals with the experimental results obtained during BTA drilling on EN-9 steel for different machining conditions. The data presented here are mainly on size variation, straightness of axis, out of roundness and surface finish. A different approach has been followed to study the error on the straightness of axis. [ABSTRACT FROM AUTHOR]

Presents a methodology of predicting the maximum possible out-of-roundness of the hole produced in BTA deep hole machining as a function of certain machining parameters. Parametric analysis of the out-of-roundness index; Definition of an index describing the upper bound of the roundness index.

Experiments are described in which mild steel plates of 1/16 in. thickness were set on hardened and ground flat steel dies having central square-shouldered round holes, of diameter ranging from 1/16 to 1 1/4 in., and subjected to the shock wave resulting from the detonation of an underwater high explosive charge. Graphical results are presented showing the variation of the deformation of the plates due to cupping and to shear, with increasing charge size, and with varying hole diameter.
Results from records of the pressure wave arising from the detonation of the charge are provided, and attempts are made to correlate these with the predictions of established empirical formulae. [ABSTRACT FROM AUTHOR]

This article deals with the homogenization of the Poisson equation in a bounded domain of , d > 2, which is perforated by a random number of small spherical holes with random radii and positions. We show that for a class of stationary short-range correlated measures for the centres and radii of the holes, we recover in the homogenized limit an averaged analogue of the 'strange term' obtained by Cioranescu and Murat in the periodic case [D. Cioranescu and F. Murat, Un term étrange venu d'ailleurs (1986)]. We stress that we only require that the random radii have finite -moment, which is the minimal assumption in order to ensure that the average of the capacity of the balls is finite. Under this assumption, there are holes which overlap with probability one. However, we show that homogenization occurs and that the clustering holes do not have any effect in the resulting homogenized equation. [ABSTRACT FROM AUTHOR]

Deep or large aspect ratio microholes are needed in products made of aluminum alloys that find applications in space, automotive, and other sectors. In the present work, microholes of 500 µm diameter are produced by mechanical microdrilling. By following peck drilling strategy, microholes having aspect ratio of 6 are drilled in 3-mm thick aluminum 6061-T6 plates. Microdrills being slender and having low rigidity, breakage of these drills is a common occurrence. Hence it is necessary to analyze thrust force as well as torque obtained in microdrilling. For reliable measurement, the thrust force from a dynamometer and torque from a torque sensor is acquired simultaneously using a novel arrangement. For comparison, another set of experiments is also performed to produce 0.5-mm diameter blind holes by direct drilling and the results are further discussed. The causes for increase in forces at some peck steps during microdrilling of holes are explained using the signals and images acquired during the process. By having a threshold on the drilling torque, it is possible to control the microdrilling process and minimize the microdrill breakages. [ABSTRACT FROM AUTHOR]

Second-quantised creation and annihilation operators for fermionic particles anticommute, but the same is true for the creation and annihilation operators for holes. This introduces a symmetry into the quantum theory of fermions that is absent for bosons. In ab initio electronic structure theory, it is common to classify methods by the number of electrons for which the method returns exact results: for example Hartree-Fock theory is exact for one-electron systems, whereas coupled-cluster theory with single and double excitations is exact for two-electron systems. Here, we discuss the generalisation: methods based on approximate wavefunctions that are exact for n-particle systems are also exact for n-hole systems. Novel electron correlation methods that attempt to improve on the coupled-cluster framework sometimes retain this property, and sometimes lose it. Here, we argue for retaining particle-hole symmetry as a desirable design criterion of approximate electron correlation methods. Dispensing with it might lead to loss of n-representability of density matrices, and this in turn can lead to spurious long-range behaviour in the correlation energy. [ABSTRACT FROM AUTHOR]

A pressure relief technique has been proposed to reduce hydrostatic pressures by opening drainage holes around a water tank. This solution is evaluated by laboratory experiments and numerical parametric investigation. After seepage flow is allowed, the hydraulic head acting on the water tank is reduced due to seepage losses. The drainage holes should be opened on the base slab near the sidewalls, and at a certain height on the sidewalls. Given a fixed total opening area, the number of drainage holes with smaller diameter should be allowed near the edge of the water tank to increase the efficacy of the approach. The properties of the surrounding soil influence the results significantly, where a cushion layer with a higher hydraulic conductivity and a greater thickness is beneficial to the stability of the water tank, and a backfill layer with adequate thickness and hydraulic conductivity should be selected. An illustrative example is given in the end to demonstrate the advantage of the proposed antiflotation design strategy compared to the conventional enhanced self-weight method, and more economic design using less reinforcement and concrete can be achieved. [ABSTRACT FROM AUTHOR]

1. In commercial free-range systems for laying hens, popholes to the outdoor range are often installed on one side of the house only. In multi-tier systems, it is possible that some individuals fail to access the range due to internal barriers to movement. 2. Five commercial multi-tier flocks from different units were studied. For each flock, two different colour markers were used to distinguish 200 birds roosting near the popholes (NP-Roost) and 200 birds roosting far from the popholes (FP-Roost) at night. The following day, counts of marked birds on the range and inside the house were performed. 3. Significantly more NP-Roost birds were observed in all areas of the outdoor range than FP-Roost birds the next day. Distance of FP area from the popholes was very strongly positively correlated with effect size in the adjacent range area. 4. Additionally, in the indoor area far from the popholes (FP) more FP-Roost birds were observed the next day than NP-Roost birds. In the indoor area near to the popholes (NP) more NP-Roost birds were observed the next day than FP-Roost birds. 5. These results suggest that roosting location is associated with differential range use when popholes are only available on one side of the shed as birds that roosted far from the popholes used the range less. [ABSTRACT FROM AUTHOR]

High-grade highways are the foundation of regional economic development. How to monitor the deformation of high-grade highways under the influence of underground mining and guarantee their safe operation is very important and is directly relevant to regional economic development. Considering that Differential interferometric synthetic aperture radar (D-InSAR) technology has low monitoring accuracy around the maximum subsidence and high-accuracy levelling can only monitor the deformation of finite number points, the method of assimilating the D-InSAR data and levelling monitoring data based on Kalman filtering theory is proposed to improve precision of regional monitoring. Research results indicate that data assimilation results based on ensemble Kalman filter are much better than the inversion results and D-InSAR data. When applied to Zouji Highway of Jining, the total RMS is 17.7 mm after assimilating the D-InSAR data and levelling monitoring data, which can meet accuracy requirements of deformation monitoring of high-grade highways. Research results are of theoretical and practical significance to guarantee safe operation of high-grade highways under the influence of mining activities. [ABSTRACT FROM AUTHOR]

Fences are utilised throughout the world to restrict the movements of wildlife, protecting them from threats and reducing human–wildlife conflict. In South Africa the number of privately-owned fenced game reserves has greatly increased in recent years, but little is known about how fencing affects the distribution and movements of target and non-target mammals. We surveyed 2 m either side of the complete fence line of a recently established commercial game reserve in South Africa, identifying signs of animal presence (spoor, scat, foraging or other field signs) while also recording damage (holes) to the fence. Every 250 m we carried out 100 m perpendicular transects either side of the fence, recording vegetation cover and height at 10 m intervals along the transect. We found that livestock (largely cattle) were excluded from the reserve. However, 12% of records of large animal species were recorded outside of the fence line. These species had been introduced to the reserve, strongly suggesting that they had crossed the boundary into the surrounding farmland. Sixteen naturally present wild species were found on both sides of the fence, but we found more evidence of their presence inside the reserve. Observational evidence suggests that they were regularly crossing the boundary, particularly where the fence was damaged, with hole size affecting species recorded. We also found evidence that the construction of the fence had led to a difference in vegetation structure with plant richness and percentage of non-woody plant cover significantly higher inside the fence. While fencing was highly effective at preventing movement of livestock, introduced and wild animals were able to cross the boundary, via holes in the fence. This work shows that the efficacy of the most common approach to preventing animal movement around protected areas depends on the species being considered and fence condition. [ABSTRACT FROM PUBLISHER]

In this paper, we develop and analyze an adaptive multiscale approach for heterogeneous problems in perforated domains. We consider commonly used model problems including the Laplace equation, the elasticity equation, and the Stokes system in perforated regions. In many applications, these problems have a multiscale nature arising because of the perforations, their geometries, the sizes of the perforations, and configurations. Typical modeling approaches extract average properties in each coarse region, that encapsulate many perforations, and formulate a coarse-grid problem. In some applications, the coarse-grid problem can have a different form from the fine-scale problem, e.g. the coarsegrid system corresponding to a Stokes system in perforated domains leads to Darcy equations on a coarse grid. In this paper, we present a general offline/online procedure, which can adequately and adaptively represent the local degrees of freedom and derive appropriate coarsegrid equations. Our approaches start with the offline procedure, which constructs multiscale basis functions in each coarse region and formulates coarse-grid equations. We presented the offline simulations without the analysis and adaptive procedures, which are needed for accurate and efficient simulations. The main contributions of this paper are (1) the rigorous analysis of the offline approach, (2) the development of the online procedures and their analysis, and (3) the development of adaptive strategies. We present an online procedure, which allows adaptively incorporating global information and is important for a fast convergence when combined with the adaptivity. We present online adaptive enrichment algorithms for the three model problems mentioned above. Our methodology allows adding and guides constructing new online multiscale basis functions adaptively in appropriate regions. We present the convergence analysis of the online adaptive enrichment algorithm for the Stokes system. In particular, we show that the online procedure has a rapid convergence with a rate related to the number of offline basis functions, and one can obtain fast convergence by a sufficient number of offline basis functions, which are computed in the offline stage. The convergence theory can also be applied to the Laplace equation and the elasticity equation. To illustrate the performance of our method, we present numerical results with both small and large perforations. We see that only a few (1 or 2) online iterations can significantly improve the offline solution. [ABSTRACT FROM AUTHOR]

Introduction:Subcutaneous face and neck emphysema secondary to colonic perforation is a rare complication of colonoscopy. Presentation may be complicated by pneumothorax and/or respiratory distress. Evidence limited to case studies. Therefore, no management consensus of these rarely reported cases exists. Methods:All cases published on PubMed between 1 January 2000–1 November 2016 reporting subcutaneous face and/or neck emphysema after colonoscopy are included. Management is discussed with trends identified. We report a case of a patient undergoing routine polypectomy who developed subcutaneous emphysema of the face, neck and thorax with a pneumothorax and pneumoretroperitoneum. Results:37 cases were found (mean age = 64.1 ± 15.09 years). The majority (n = 24) were managed non-operatively. Conservative and operative management had mean inpatient stays of 7.6 ± 4.65 and 19.5 +/- 21.62 days respectively. Sixteen cases had a concomitant pneumothorax with nine (56.3%) requiring decompression. No mortalities occurred. Conclusion:An understanding of anatomy heightens awareness of the rare complication of face and/or neck surgical emphysema, secondary to pneumoretroperitoneum and pneumothorax, after perforation of the colon during endoscopy. Management remains controversial with expectant conservative bowel rest with antibiotics and operative intervention described. Conservative management had a shorter inpatient stay and was more common in younger patients. [ABSTRACT FROM PUBLISHER]

Adnexal and periocular involvement in Neisseria gonorrhoeae (NG) infection is rare. This report describes the case of a patient with a delayed diagnosis of gonococcal dacryoadenitis with contiguous conjunctivitis and corneal involvement. She underwent extensive inpatient laboratory and infectious workup but rapidly progressed to corneal perforation requiring emergent penetrating keratoplasty prior to a positive culture confirming the diagnosis. To date, this is the first reported case of ophthalmologic NG infection with associated conjunctivitis, dacryoadenitis, and corneal perforation. [ABSTRACT FROM AUTHOR]

Roughness on rock joints produces a variable aperture across the joints and increases the flow path length. These conditions should be taken into account for a good approximation from cubic law. In this paper, the concept of local true aperture and tortuosity is applied to assumed joints where surfaces are matched to each other and correspond with standard Joint Roughness Coefficient (JRC) profiles. Furthermore, the hydraulic behaviour of JRC profiles is studied by a new laboratory experiment setup. The analytical approach provides new insights into the effects of roughness on hydraulic properties of rock joints. The results indicate that for a constant mechanical aperture, both the minimum local aperture and hydraulic aperture decrease with increasing JRC. Furthermore, tortuosity and standard deviation of local true aperture increase with JRC increment. The trend obtained between different parameters and JRC shows an obvious fluctuation for JRC lower than 10. On one hand, the results of this study along with a critical review of previous studies demonstrate that JRC profiles cannot present a precise roughness increment when JRC is less than 10. A new laboratory setup was designed to study the flow behaviour of JRC profiles. The results obtained from laboratory experiments under linear flow conditions validate the accuracy of the applied analytical method. [ABSTRACT FROM PUBLISHER]

In an effort to improve the performance of the linear sampling method in situations involving sparse data-sets, this method in inverse scattering has recently been extended from the frequency domain to the time domain. In this paper, we consider the relative merits of the time and multifrequency linear sampling methods for sparse, limited aperture, and data-sets. Among our conclusions are that, for limited aperture measurements single-frequency data can fail to reconstruct the scatterer, whereas both time and multifrequency domain data perform satisfactorily. On the other hand, if the aperture is too small all the sampling methods fail and increasing the number of measurements in a fixed size aperture is of no help. [ABSTRACT FROM AUTHOR]

Formerly unknown holes in shells of freshwater gastropods are described and assigned to the ichnogenusNihilichnus. The smaller size range, the different substrate, and the sometimes present scratchings around the holes distinguish our praedichnion from the type ichnospeciesN. nihilicus, and we proposeN. covichin. isp. for the herein presented material. The type material ofN. covichin. isp. derives from the middle Miocene (Mammal Neogene zones MN6 and MN7) lake sediments of the Steinheim Basin (Steinheim am Albuch, SW Germany); the holes occur in shells ofGyraulus trochiformis(Planorbidae) andBania pseudoglobulus(Hydrobiidae). Further material consists of perforated shells ofNematurella bavarica(Hydrobiidae) andGalba armaniacensis(Lymnaeidae) from the early Miocene Kirchberg Formation (MN 4; SE Germany). In contrast to the other morphologically similar but marine praedichnia (e.g.,Belichnus and Oichnus, recently synonymized withSedilichnus),Nihilichnusis known from terrestrial, palustrine, freshwater (reported herein), and marine environments.Nihilichnus covichin. isp. was probably produced by the pharyngeal teeth of durophagous tench fish (Tincaspp.; Cyprinidae). [ABSTRACT FROM AUTHOR]

We investigate the behavior of the solution of a mixed problem in a domain with two moderately close holes. We introduce a positive parameter ε and we define a perforated domain Ωεobtained by making two small perforations in an open set. Both the size and the distance of the cavities tend to 0 as ε → 0. For ε small, we denote byuεthe solution of a mixed problem for the Laplace equation in Ωε. We describe what happens touεas ε → 0 in terms of real analytic maps and we compute an asymptotic expansion. [ABSTRACT FROM AUTHOR]

Micro-electrical discharge machining (EDM) is a slow process as compared to laser machining, on the contrary laser machining lacks good surface quality. To overcome the drawbacks of both these processes, this paper suggests a hybrid machining process which combines laser and micro-EDM processes for drilling microholes in advanced engineering materials such as Nickel–Titanium (Ni–Ti)-based shape memory alloy. To achieve the objective of the suggested hybrid process, pilot holes are drilled with laser machine and rimmed out by micro-EDM drilling. The suggested process requires investigation of various combinations of micro-EDM drilling process conditions to obtain optimum machining parameters for the hybrid process. It has been found that the proposed hybrid machining process resulted in 50–65% reduction in machining time without affecting the quality of microholes as compared to the standard micro-EDM process. [ABSTRACT FROM PUBLISHER]

Many facilities for urban drainage systems are equipped with a pipe overflow structure that can often be treated as a circular broad-crested weir. Thus it is possible to evaluate the overflow discharge through this device by measuring the water levels in the upstream tank and at the outlet of the pipe. In the present study, computational fluid dynamics (CFD) is used to determine a relationship between the discharge and the water levels upstream and downstream of the orifice for a range of diameters between 200 and 600mm and a relative head up to 2. Over 50 numerical simulations are performed to take into account all the operating conditions of the system: free flow, submerged flow and pressurized flow. A regression is applied to the resulting data in order to obtain an orifice equation valid in both free-flow and submerged-flow regimes. Specific formulas, derived from Bernoulli's theorem, are also given for pressurized flows. The proposed methodology is applied to two examples. [ABSTRACT FROM AUTHOR]

Drilling is one of the processes where lasers have been successfully applied. Laser assisted drilling process offers combined advantages of a conventional drilling process and a laser heating process. An experimental investigation of a laser assisted drilling process was conducted in this study. 41Cr4, C45E4, stainless steel and cast iron were used as workpiece materials and a fibre laser was employed with the beam formed into an ellipse shape. Results show that compared with laser pre-heating, the initial hole diameters are improved more than 122.7% for 41Cr4, 85.9% for C45E4 and 140.7% for stainless steel, and the drilling time is shortened over 18.6% for cast iron, 16.3% for C45E4 and 39.9% for stainless steel in the laser assisted drilling process, which produces less tool wear and a higher production rate. [ABSTRACT FROM AUTHOR]

This study has focused on the evaluation of the influence of different input variables (cobalt content, thickness of workpiece, tool profile, tool material, size of abrasive grains, and power rating) on the hole quality (dimensional and form accuracy) obtained in ultrasonic machining of WC-Co composite material. Taguchi's approach has been employed for planning the experiments and optimization of the experimental results. Three measures of hole quality (hole oversize, out of roundness, and conicity) have been investigated under controlled experimental conditions. The experimental results showed that abrasive grit size and power rating were most influential for the hole quality. Hole quality has been found to be improved at higher cobalt content, whereas it is found to be degraded with the use of coarse grit size. [ABSTRACT FROM AUTHOR]

Cut-off grade – a criterion used to discriminate ore from waste – has direct impact on mineable reserves and average grade of the materials that must be processed. The most comprehensive method for determination of optimum cut-off grades in metal deposits with the goal of maximising the net present value is provided by Lane’s algorithm. Lane’s algorithm includes income and the production costs of the final product, mining, processing and refinery capacities and grade distribution of the ore deposit, but he did not consider the reclamation costs and incomes. This study provides a model for determination of cut-off grades in open-pit mines. In this model, in addition to costs associated with management and reclamation of waste dumps, tailing dam and pits, possible incomes from reclamation are also considered. Developed model has been verified by data gathered from Gol-Gohar iron mine of Iran and results indicated that there is some important improvement in mine project goal. [ABSTRACT FROM AUTHOR]

Solid-state materials, such as small-cavity zeolites, carbon and boron nitride nanotubes, etc., as well as organic molecular cavities and containers, such as calix-, resorcin-, pillar[n]arenes, etc., offer great potential for their applications for the selective optical and/or electrochemical detection, extraction and storage (via encapsulation) of NOxspecies (N2O, NO, NO2/N2O4, etc.), among others (O2, CO2, SOx, etc.). This is of great importance, since NOxspecies are known as environmental pollutants and physiologically active compounds. This review is focused on the recent advances on the detection and effective storage of NOxgases with the employment of both organic molecular cavities and containers and inorganic solid-state materials. The effects of structural variations, including the NOxrecognition mode, type of the material (inorganic or organic), geometric sizes, and conformation variations, are discussed. [ABSTRACT FROM PUBLISHER]