Methodology for Assessing the Stability of Drilling Rigs Based on Analytical Tests

Underground mining machines, such as wheel-tyre drilling rigs, are articulated and equipped with booms that project far beyond the undercarriage. Such a structure makes these machines prone to losing stability. Hence, it is necessary to analyse the distribution of masses and geometry as well as their broadly understood stability during the entire design process, taking into account many factors resulting from the manner and conditions of their operation. However, there are no appropriate computational models that would enable analytical tests to be carried out for machines with this kind of construction. This article is concerned with the author’s computational model, which allows the stability of single- and twin-boom drilling rigs to be quickly assessed. The model makes it possible to perform analyses without having to solve differential equations that are present in dynamic models or using specialist software based on CAD and CAE tools. The developed model allows determination of the pressure of wheels and jacks as a function of many important parameters and variables. Additionally, the distances of the centre of gravity from the tipping edge are calculated. The developed computational model was verified by comparing the obtained results with the results of the full dynamic model, the results of model tests carried out in the CAD/CAE program, and the results of empirical tests of wheel and jack pressures on the ground for the selected drilling rig. The model was subjected to verification and validation, which proved that it was fully correct and useful. The model was used to prepare a practical and user-friendly calculation sheet. Apart from the numerical values, the calculation sheet contains a graphical representation of the machine, the location of the centre of gravity, the tipping edges, as well as graphs of the wheel and jack pressures. Next, analytical tests of the stability of the selected drilling rig were carried out. The obtained calculation results are consistent with the results of empirical research. The computational model and the spreadsheet provide handy tools used during the design process by one of the Polish company’s producing drilling rigs.

EXPERIMENTAL INVESTIGATION INTO THE EFFECTS OF REDUCED VERTICAL CENTRE OF GRAVITY OF AN ARTICULATED CONCRETE MATTRESS IN CURRENT FLOW

An articulated concrete mattress model has been utilised to investigate the effects of reduced vertical centre of gravity on the stability of a 400 series block. Experimental testing was conducted at the AMC CWC, Beauty Point. To determine the effects that a reduced centre of gravity has on stability, the 3 by 3 articulated concrete mattress model was subject to pure uniform current flow. The subsequent forces were analysed with a six degree of freedom underwater force sensor. In order to gain a range of real world scenarios, the experimental model was tested at six flow angles ranging from -15 degrees through to 60 degrees, at 15 degree increments. Additionally, five fluid velocities starting at 0.6 m/s through to 1.4 m/s, at 0.2 m/s increments were investigated. These results explain how the inversion of a 400 series block increases its hydrodynamic coefficients and subsequently decreases its stability performance in current flow. Ultimately, this study provides experimental information for the installation of 400 series articulated concrete mattresses in the inverted orientation.

Settle Down! Ranging Behaviour Responses of Roe Deer to Different Capture and Release Methods

The fitting of tracking devices to wild animals requires capture and handling which causes stress and can potentially cause injury, behavioural modifications that can affect animal welfare and the output of research. We evaluated post capture and release ranging behaviour responses of roe deer (Capreolus capreolus) for five different capture methods. We analysed the distance from the centre of gravity and between successive locations, using data from 14 different study sites within the EURODEER collaborative project. Independently of the capture method, we observed a shorter distance between successive locations and contextual shift away from the home range centre of gravity after the capture and release event. However, individuals converged towards the average behaviour within a relatively short space of time (between 10 days and one month). If researchers investigate questions based on the distance between successive locations of the home range, we recommend (1) initial investigation to establish when the animals start to behave normally again or (2) not using the first two to three weeks of data for their analysis. We also encourage researchers to continually adapt methods to minimize stress and prioritize animal welfare wherever possible, according to the Refinement of the Three R’s.

Effect of emphasis spread on VOT in coronal stops in Qatari Arabic

Emphasis (contrastive pharyngealization of coronals) in Arabic spreads from an emphatic consonant to neighboring segments. Previous research suggests that in addition to changing spectral characteristics of adjacent segments, emphasis might affect voice onset time (VOT) of voiceless stops because emphatic stops in Arabic dialects have considerably shorter VOT than their plain cognates. No study investigated whether emphatic co-articulation could shorten VOT in plain stops produced in emphatic environment. The present study investigates changes in VOT in syllable-initial /t/ using production data from sixteen speakers of Qatari Arabic, who read non-word syllables with initial plain and emphatic stops /t/ and /ṭ/ adjacent to another plain or emphatic consonant. The results show that emphasis spread is a gradient process that affects only spectral characteristics of segments, causing changes in vowel formants and spectral centre of gravity of stops. Long-lag VOT in plain /t/, however, was not shortened in emphatic syllables. The findings suggest that shorter VOT in voiceless emphatic stops in Qatari Arabic is not a mechanical aftermath of pharyngealization but, rather, a phonological requirement to maintain contrast between long-lag and short-lag VOT in plain and emphatic stops.

Conan Doyle: Man of Letters, Man About Town

This essay attempts to deduce Conan Doyle’s map of London from the writings of his long career and particularly his autobiography Memories and Adventures (1924). Here we can find a portrait of the layers of late-Victorian London: the historic centre of government, business, and the great institutions of national culture, the old working-class areas that surround it, and the new suburbs sprawling in every direction. In magazine and publishing offices, in West End theatres, in gentlemen’s clubs including the Authors’ Club, and in public and private dining rooms, Conan Doyle participated in the largely masculine business of literature as a highly clubbable man of letters who was also an energetic man about town. He journeyed into and across the city, coming in from the suburbs or up from the country. These journeys were repeated on a global scale as he travelled to foreign health resorts, battlefields in Africa and Europe, or on overseas lecture tours, always returning to the imperial and cultural capital, the centre of gravity of his life and work.

A General Framework for Crankshaft Balancing and Counterweight Design

In the automotive field, the requirements in terms of carbon emissions and improved efficiency are shifting the focus of designers towards reduced engine size. As a result, the dynamic balancing of an engine with strict limitations on the number of cylinders, the weight and the available space becomes a challenging task. The present contribution aims at providing the designer with a tool capable of selecting fundamental parameters needed to correctly balance an internal combustion engine, including the masses and geometry of the elements to be added directly onto the crankshaft and onto the balancing shafts. The relevant elements that distinguish the tool from others already proposed are two. The first is the comprehensive matrix formulation which makes the tool fit for a wide variety of engine configurations. The second is an optimisation procedure that selects not only the position of the mass and centre of gravity of the counterweight but also its complete geometric configuration, thus instantaneously identifying the overall dimensions and weight of the crankshaft.

A Comparison of Postural Responses in a Virtual and a Real Environment, a Randomised Controlled Study.

BackgroundImmersive virtual reality solutions are seeing increasing usage in functional rehabilitation programmes. However, there is no reference that allows us to confirm that these environments present the same characteristics and therefore the same degree of safety and training in postural responses for balance.QuestionThe aim of the study was to compare displacements from centre of gravity (distance covered and surface used) in balance tests, comparing the real situation to an identical virtual situation. Participants 70 healthy subjects aged between 18 and 65 were recruited in two centres. DesignThe study used a one-way repeated-measures design with randomisation of the order in which the two test conditions were performed. Intervention: .The first test condition was "real", taking place in a bedroom of a treatment centre apartment, and the second was virtual, with the room reproduced and seen through a HMD. For each condition, two static tests (left leg, right leg) and two dynamic tests (left and right) were performed. Each test included three attempts. Outcome measuresThe displacement from the centre of gravity was recorded on a force plate.Result69 participants completed all of the tests and were analysed. None of the tests resulted in confirmation that the virtual was equivalent to the real (Two One-Sided Tests for left static, right static, left dynamic, right dynamic; surface respectively p = 0.592, p = 0.151, p = 0.238, p = 0.503; distance respectively p = 1.00, p = 0.91, p = 0.0742, p = 1.00). Furthermore 6 tests of out 8 showed a significant and considerable difference (surface respectively p = 0.00249, p = 0.0664, p = 0.0318, p = 0.00483; distance respectively p = 1.12 x 10-8, p = 5.27 x 10-5, p = 0.153, p = 2.55 x 10-9). ConclusionPostural responses were poorer in the immersive virtual environment, both on the static and dynamic balance tests. The offer of balance rehabilitation in immersive VR raises safety issues and consequently ethical issues that are as yet unresolved. Researchers must test solutions to correct this serious problem. Trial registration: The study is registered at the US National Institutes of Health (ClinicalTrials.gov) NCT04574726

Model-Based Energy Path Analysis of Tip-In Event in a 2WD Vehicle with Range-Extender Electric Powertrain Architecture

Vehicle driveability is one of the important attributes in range-extender electric vehicles due to the electric motor torque characteristics at low-speed events. Physical vehicle prototypes are typically used to validate and rectify vehicle driveability attributes. However, this can be expensive and require several design iterations. In this paper, a model-based energy method to assess vehicle driveability is presented based on high-fidelity 49 degree-of-freedom powertrain and vehicle systems. Multibody dynamic components were built according to their true centre of gravity relative to the vehicle datum to provide an accurate system interaction. The work covered a frequency of less than 20 Hz. The results consist of the components’ frequency domination, which was structured and examined to identify the low-frequency resonances sensitivity based on different operating parameters such as road surface coefficients. An energy path method was also implemented on the dominant component by decoupling its compliances to study the effect on the vehicle driveability and low-frequency resonances. The outcomes of the research provided a good understanding of the interaction across the sub-systems levels. The powertrain rubber mounts were the dominant component that controlled the low-frequency resonances (<15.33 Hz) and can change the vehicle driveability quality.

Estimation of Wheels' Normal Reaction Forces of Automobile in Steady-State Curvilinear Motion

Computer simulation seems to be one of the cheapest and relatively fast methods of investigating vehicle motion. Thereby, it may be important in the case of calculations for the reconstruction of traffic incidents. In particular, that may be important to answer the following question: How wheels' normal reaction forces differ during the cornering of a vehicle? In this article, the authors presented how the normal reaction forces vary in the case of roll motion of a vehicle body. Suitable mathematical equations are presented. Furthermore, the measurements of the height of the centre of gravity were performed, which was necessary to obtain the normal reaction forces while vehicle body rolls. The authors decided to apply dimensionless coefficients, which represented the properties of a front and rear suspension. Additionally, dimensionless parameters were applied to consider the impact of asymmetrical distribution of vehicle load on normal reaction forces of wheels on a road surface.

Solid-state ¹H spin polarimetry by ¹³CH₃ nuclear magnetic resonance

Dissolution dynamic nuclear polarization is used to prepare nuclear spin polarizations approaching unity. At present, 1H polarization quantification in the solid state remains fastidious due to the requirement of measuring thermal equilibrium signals. Line shape polarimetry of solid-state nuclear magnetic resonance spectra is used to determine several useful properties regarding the spin system under investigation. In the case of highly polarized nuclear spins, such as those prepared under the conditions of dissolution dynamic nuclear polarization experiments, the absolute polarization of a particular isotopic species within the sample may be directly inferred from the characteristics of the corresponding resonance line shape. In situations where direct measurements of polarization are complicated by deleterious phenomena, indirect estimates of polarization using coupled heteronuclear spins prove informative. We present a simple analysis of the 13C spectral line shape of [2-13C]sodium acetate based on the normalized deviation of the centre of gravity of the 13C peaks, which can be used to indirectly evaluate the proton polarization of the methyl group moiety and very likely the entire sample in the case of rapid and homogeneous 1H–1H spin diffusion. For the case of positive microwave irradiation, 1H polarization was found to increase with an increasing normalized centre of gravity deviation. These results suggest that, as a dopant, [2-13C]sodium acetate could be used to indirectly gauge 1H polarizations in standard sample formulations, which is potentially advantageous for (i) samples polarized in commercial dissolution dynamic nuclear polarization devices that lack 1H radiofrequency hardware, (ii) measurements that are deleteriously influenced by radiation damping or complicated by the presence of large background signals and (iii) situations where the acquisition of a thermal equilibrium spectrum is not feasible.