Instrument Location Research Articles

The Macromolecular Femtosecond Crystallography Instrument at the Linac Coherent Light Source.

The Macromolecular Femtosecond Crystallography (MFX) instrument at the Linac Coherent Light Source (LCLS) is the seventh and newest instrument at the world's first hard X-ray free-electron laser. It was designed with a primary focus on structural biology, employing the ultrafast pulses of X-rays from LCLSat atmospheric conditions to overcome radiation damage limitations in biological measurements. It is also capable of performing various time-resolved measurements. The MFX design consists of a versatile base system capable of supporting multiple methods, techniques and experimental endstations. The primary techniques supported are forward scattering and crystallography, with capabilities for various spectroscopic methods and time-resolved measurements. The location of the MFX instrument allows for utilization of multiplexing methods, increasing user access to LCLS by running multiple experiments simultaneously.

Mining-Induced Deformation in the Malmberget Mine

The Norra Alliansen orebody of the Malmberget sublevel caving mine consists of iron ore interspersed with biotite schist and granitic inclusions. The schist is squeezed between the ore and the host rock and in direct contact with the ore along the majority of the length of the footwall. The schist exhibits high deformation when exposed to stress. SMART cable bolt roof deformation measurements are re-analyzed to draw conclusions regarding the patterns of deformation in the mine. Each bolt’s head is placed at the origin of a spherical coordinate system and the radius and inclination angle between the bolt and every production blast occurring during the bolt’s recorded lifetime are calculated. The deformation experienced by each instrument is investigated by comparing the long-term recorded movements with the developed geometric variables. Patterns of deformation magnitude and rate are found with respect to production-blast distance and inclination angle, instrument location, rock quality designation, and likely mining-induced stresses. Results show that deformation magnitude tends to be higher when driven by production blasting occurring on the production level above the instrumentation when accounting for the effects of distance, but average deformation magnitude for very-near production blasts tends to be higher than that for production blasts occurring directly above the instrument. Correlations also exist between the measured RQD, estimated rockmass parameters, and the measured deformation. Empirical evidence allows the identification of six scenarios which account for 91% of the recorded high-deformation-rate events. These scenarios help determine which production activities are most likely to cause high deformation rates.

Musical Source Separation: An Introduction

Many people listen to recorded music as part of their everyday lives, e.g., from radio or TV programs, compact discs, downloads, or, increasingly, online streaming services. Sometimes we might want to remix the balance within the music, perhaps to make the vocals louder or to suppress an unwanted sound, or we might want to upmix a two-channel stereo recording to a 5.1-channel surround sound system. We might also want to change the spatial location of a musical instrument within the mix. All of these applications are relatively straightforward, provided we have access to separate sound channels (stems) for each musical audio object.

Revisiting Earthquakes in the Los Angeles, California, Basin During the Early Instrumental Period: Evidence for an Association With Oil Production

AbstractA total of seven independent ML ≥ 4.0 earthquakes occurred in the Los Angeles, California, basin, during the early instrumental period between 1932 and 1952, the largest of which was the 1933 Long Beach earthquake. Revising available macroseismic and instrumental data for a total of 6 4.0 ≤ ML ≤ 5.1 events between 1938 and 1944, we conclude that early instrumental locations can be grossly inconsistent with detailed macroseismic data. We use available macroseismic data to revisit event locations. We further present evidence that most if not all of these moderate earthquakes may have been induced by oil production. We quantify the predicted stress change associated with production from eight oil fields in the southwestern Los Angeles basin and show that frictional failure would have been encouraged beneath and at the periphery of high‐volume fields, with stress changes upward of 0.1 MPa at 5‐km depth. The results suggest that if earthquakes are induced by stress changes associated with production, the magnitudes of events might tend to be limited by the limited spatial extent of lobes of increased Coulomb failure stress. It further appears that the advent of fluid injection recovery methods (water‐flooding) around 1960 mitigated induced earthquake risk considerably.

Normal mode simulation of prompt elastogravity signals induced by an earthquake rupture

As soon as an earthquake starts, the rupture and the propagation of seismic waves redistribute masses within the Earth. This mass redistribution generates in turn a long-range perturbation of the Earth gravitational field, which can be recorded before the arrival of the direct seismic waves. The recent first observations of such early signals motivate the use of the normal mode theory to model the elastogravity perturbations recorded by a ground-coupled seismometer or gravimeter. Complete modelling by normal mode summation is challenging due to the very large difference in amplitude between the prompt elastogravity signals and the direct P-wave signal. We overcome this problem by introducing a two-step simulation approach. The normal mode approach enables a fast computation of elastogravity signals in layered self-gravitating Earth models. The fast and accurate computation of gravity perturbations indicates instrument locations where signal detection may be achieved, and may prove useful in the implementation of a gravity-based earthquake early warning system.

Understanding track substructure behavior: Field instrumentation data analysis and development of numerical models

Abstract Numerous studies have targeted using numerical modeling, field instrumentation, or combinations of both to gain insight into track substructure behavior under loading. In-depth understanding of track substructure behavior serving both passenger and freight trains is critical to developing suitable design and maintenance/rehabilitation methods to ensure adequate performance under loading. This manuscript presents findings from a recently completed study involving advanced instrumentation and numerical modeling to investigate track substructure-related issues at several problematic railroad bridge approaches in the United States. Multi-Depth Deflectometers (MDDs) were installed to measure transient as well as plastic deformations experienced by track substructure layers under loading. Strain gauges were installed on the rail web to measure the vertical wheel loads applied during train passage. Data from the field instrumentation was used to make inferences regarding the relative contributions of different substructure layers towards the differential movement problem. A 3-D Finite Element (FE) model was developed to further understand the behavior of the instrumented locations, and was calibrated using the field instrumentation data. An elastic layered track analysis program, GEOTRACK, was first used to iteratively backcalculate individual track substructure layer moduli from the field measurements; these backcalculated modulus values were subsequently used in the FE model to predict track response under transient loading conditions. Modulus values estimated for the ballast layer were found to be significantly affected by the presence of gaps at the tie-ballast interface at track transitions. Once validated, the model was further modified to match transient displacement results acquired in the field using a quasi-static moving load approach. Good agreement was found between the model predictions and field instrumentation results. Development of advanced numerical models augmented by field instrumentation data can facilitate the design and maintenance of well-performing track structures.

Assessment and comparison of target registration accuracy in surgical instrument tracking technologies.

Image guided surgery systems aim to support surgeons by providing reliable pre-operative and intra-operative imaging of the patient combined with the corresponding tracked instrument location. The image guidance is based on a combination of medical images, such as Magnetic Resonance Imaging (MRI), Computed Tomography (CT) and Ultrasonography (US), and surgical instrument tracking. For this reason, tracking systems are of great importance as they determine location and orientation of the equipment used by surgeons. Assessment of the accuracy of these tracking systems is hence of the utmost importance to determine how much error is introduced in image guided surgery only due to tracking inaccuracy. Thus, this study aimed to compare in a surgical Operating Room (OR) accuracy of the two most used tracking systems, Optical Tracking (OT) and Electromagnetic Tracking (EMT), in terms of Target Registration Error (TRE) assessment at multiple distances from the target position. Results of the experiments show that optical tracking performs more accurately in tracking the instrument tip than electromagnetic tracking in the experimental conditions. This was tested using a phantom designed for accuracy measurement in a wide variety of positions and orientations. Nevertheless, EMT remains a viable option for flexible instruments, due to its reliability in tracking without the need for line of sight.

Investigation of Active Identification Methods for Thermohydraulic Testing of Heat Networks

Considerable uncertainty of the information about actual characteristics and parameters is the key factor restricting the effective use of mathematical modeling and computer simulation methods in solving problems of optimal retrofitting, commissioning, development of operating regimes, and dispatch control of heat networks. Application of the existing industrial procedures in testing a heat network for hydraulic and heat losses does not make the issue less urgent, because of the fact that the test conditions have not been properly standardized as yet and no guarantee is provided for the completeness and accuracy of the obtained results. The employment of the available methods of parametric identification during passive monitoring of heat networks during their normal operation does not ensure that the required solution will be obtained due to insufficient number of measurement points and a narrow range where the operating conditions can be varied. The paper presents a unique formalization of the problems of testing heat networks for hydraulic and heat losses as problems of active identification assuming optimal planning and processing of the test results with the use of a mathematical model of steady-state thermohydraulic regimes. A description of the model, a substantiation of selection of test optimality criteria, mathematical formulations of problems for optimal planning of test conditions and optimal location of instruments, and test result processing procedures are presented. The proposed procedure is in a step-wise test strategy giving maximum information with a minimal risk that too many tests will be performed. It is applicable for testing various types of heat networks having any structure or configuration. The potential efficiency of simultaneous performance of thermal and hydraulic testing of a heat network is demonstrated for the first time theoretically and by an example. It manifests itself in minimizing the total number of experiments required for reaching the prespecified accuracy in determining the actual characteristics of heat networks and of the model predictions.

Cluster analysis of microclimate data to optimize the number of sensors for the assessment of indoor environment within museums.

For the first time, the cluster analysis (k-means) has been applied on long time series of temperature and relative humidity measurements to identify the thermo-hygrometric features in a museum. Based on ASHRAE (2011) classification, 84% of time all rooms in the Napoleonic Museum in Rome (case study) were found in the class of control B. This result was obtained by analyzing all recorded data in 10 rooms of the museum as well as using the cluster aggregation. The use of objective-oriented methodology allows to achieve an acceptable knowledge of the microclimate in case of multi-room buildings, reducing computations with large amounts of collected data and time-consuming in redundant elaborations. The cluster analysis enables to reduce the number of the sensors in microclimate monitoring programs within museums, provided that the representativeness of the instrument location is known, and professional conservators have assessed that the artifacts are well preserved.

Management of Separated Instruments in Apical Third of Extremely Curved Canals: A Case Report

This report describes the case of a 23 years old male patient who presented with the chief complaint of pain in mandibular right lower first molar tooth. Detailed clinical and radiographic examination revealed acute pulpitis in lower right second premolar and first molar teeth. During root canal instrumentation, a rotary instrument separated at the apical third of mesiobuccal canal. After careful assessment, it was decided to bypass the instrument and obturate the root canal space with warm vertical compaction using thermoplasticized gutta percha and resin based sealer materials. After considering the curvature of canal, thin root of tooth and location of broken instrument in the apical third of canal space, attempts of instrument removal were ruled out as a treatment option for the patient. Bypassing the broken instrument fragment with pre-curved hand files of small sizes was chosen as a predictable treatment option since it is not associated with removal of excessive remaining dentin from the roots of the teeth. Hence, teeth do not become weak and risk of post-operative root fracture is minimized. Due to successful bypassing and preparation of root canal space beyond broken instrument, canal was shaped, cleaned and disinfected adequately. Decision of instrument bypassing or removal should be taken with extreme care. Bypassing the instrument in apical third of root canal space with thin rooted teeth is the most conservative and practical approach, and objectives of adequate shaping and cleaning of canals can be achieved successfully without compromising remaining tooth structure.

Retrieval outcome of separated endodontic instruments by Saudi endodontic board residents: A Clinical retrospective study

Aim: This study aims to evaluate the retrieval outcome of the separated endodontic instrument by endodontic board residents. Materials and Methods: Records of 450 endodontic cases with separated endodontic instruments treated by endodontic Saudi board residents were randomly selected. The evaluation was based on the tooth type, type of fractured instrument, incidence and anatomical location in the root canal and if the instrument was retrieved, bypassed, or left. Data were statistically analyzed using IBM-SPSS.22. Results: A total of 84 (19%) separated instruments were identified. Thirty-four cases (7.55%) with separated instruments out of the total evaluated cases were done by residents. The incidence between hand stainless steel and nickel-titanium instruments was statistically significant (P Conclusions: Regardless of little experience of the endodontic residents, they were successfully managed to remove or bypass most of the separated instruments. Ultrasonic device was very helpful in removing the separated instrument.

Analysis of monitored ground support and rock mass response in a longwall tailgate entry

A comprehensive monitoring program was conducted to measure the rock mass displacements, support response, and stress changes at a longwall tailgate entry in West Virginia. Monitoring was initiated a few days after development of the gateroad entries and continued during passage of the longwall panels on both sides of the entry. Monitoring included overcore stress measurements of the initial stress within the rock mass, changes in cable bolt loading, standing support pressure, roof deformation, rib deformation, stress changes in the coal pillar, and changes in the full three-dimensional stress tensor within the rock mass at six locations around the monitoring site. During the passage of the first longwall, stress measurements in the rock and coal detected minor changes in loading while minor changes were detected in roof deformation. As a result of the relatively favorable stress and geological conditions, the support systems did not experience severe loading or rock deformation until the second panel approached within 10–15 m of the instrumented locations. After reaching the peak loading at about 50–75 mm of roof sag, the cable bolts started to unload, and load was transferred to the standing supports. The standing support system was able to maintain an adequate opening inby the shields to provide ventilation to the first crosscut inby the face, as designed. The results were used to calibrate modeled cable bolt response to field data, and to validate numerical modeling procedures that have been developed to evaluate entry support systems. It is concluded that the support system was more than adequate to control the roof of the tailgate up to the longwall face location. The monitoring results have provided valuable data for the development and validation of support design strategies for longwall tailgate entries.

When probabilistic seismic hazard climbs volcanoes: the Mt. Etna case, Italy – Part 1: Model components for sources parameterization

Abstract. The volcanic region of Mt. Etna (Sicily, Italy) represents a perfect lab for testing innovative approaches to seismic hazard assessment. This is largely due to the long record of historical and recent observations of seismic and tectonic phenomena, the high quality of various geophysical monitoring and particularly the rapid geodynamics clearly demonstrate some seismotectonic processes. We present here the model components and the procedures adopted for defining seismic sources to be used in a new generation of probabilistic seismic hazard assessment (PSHA), the first results and maps of which are presented in a companion paper, Peruzza et al. (2017). The sources include, with increasing complexity, seismic zones, individual faults and gridded point sources that are obtained by integrating geological field data with long and short earthquake datasets (the historical macroseismic catalogue, which covers about 3 centuries, and a high-quality instrumental location database for the last decades). The analysis of the frequency–magnitude distribution identifies two main fault systems within the volcanic complex featuring different seismic rates that are controlled essentially by volcano-tectonic processes. We discuss the variability of the mean occurrence times of major earthquakes along the main Etnean faults by using an historical approach and a purely geologic method. We derive a magnitude–size scaling relationship specifically for this volcanic area, which has been implemented into a recently developed software tool – FiSH (Pace et al., 2016) – that we use to calculate the characteristic magnitudes and the related mean recurrence times expected for each fault. Results suggest that for the Mt. Etna area, the traditional assumptions of uniform and Poissonian seismicity can be relaxed; a time-dependent fault-based modeling, joined with a 3-D imaging of volcano-tectonic sources depicted by the recent instrumental seismicity, can therefore be implemented in PSHA maps. They can be relevant for the retrofitting of the existing building stock and for driving risk reduction interventions. These analyses do not account for regional M > 6 seismogenic sources which dominate the hazard over long return times (≥ 500 years).

Spatial and temporal trends in fin whale vocalizations recorded in the NE Pacific Ocean between 2003-2013

In order to study the long-term stability of fin whale (Balaenoptera physalus) singing behavior, the frequency and inter-pulse interval of fin whale 20 Hz vocalizations were observed over 10 years from 2003–2013 from bottom mounted hydrophones and seismometers in the northeast Pacific Ocean. The instrument locations extended from 40°N to 48°N and 130°W to 125°W with water depths ranging from 1500–4000 m. The inter-pulse interval (IPI) of fin whale song sequences was observed to increase at a rate of 0.54 seconds/year over the decade of observation. During the same time period, peak frequency decreased at a rate of 0.17 Hz/year. Two primary call patterns were observed. During the earlier years, the more commonly observed pattern had a single frequency and single IPI. In later years, a doublet pattern emerged, with two dominant frequencies and IPIs. Many call sequences in the intervening years appeared to represent a transitional state between the two patterns. The overall trend was consistent across the entire geographical span, although some regional differences exist. Understanding changes in acoustic behavior over long time periods is needed to help establish whether acoustic characteristics can be used to help determine population identity in a widely distributed, difficult to study species such as the fin whale.

Pre-test CFD simulations of the NACIE-UP BFPS test section

The present paper is focused on the CFD pre-test analysis and design of the new experimental facility ‘Blocked’ Fuel Pin bundle Simulator (BFPS) that will be installed into the NACIE-UP (NAtural CIrculation Experiment-UPgrade) facility located at the ENEA Brasimone Research Center (Italy).The BFPS test section will carry out suitable experiments to fully investigate different flow blockage regimes in a 19 fuel pin bundle providing experimental data in support of the development of the ALFRED (Advanced Lead-cooled Fast Reactor European Demonstrator) LFR DEMO.The geometrical domain of the fuel pin bundle simulator was designed to reproduce the geometrical features of ALFRED, e.g. the external wrapper in the active region and the spacer grids. Pre-tests calculations were carried out by applying accurate boundary conditions; the conjugate heat transfer in the clad is also considered.The blockages investigated are internal blockages of different extensions and in different locations: central sub-channel blockage, corner sub-channel blockage, edge sub-channel blockage, one sector blockage, and two-sector blockage.RANS simulations were carried out adopting the ANSYS CFX commercial code with the laminar sublayer resolved by the mesh resolution. The loci of the peak temperatures and their width as predicted by the CFD simulations are used for determining the location of the pin bundle instrumentation. The CFD pre-test analysis allowed also investigating the temperature distribution in the clad to operate the test section safely.

Differential Settlements of Embankment Treated by Cement Fly-Ash Gravel Pile and Sheet Pile in Freeway Extension Constructions

The differential settlement between the newly built embankment and the old one is becoming a serious problem in the extension construction of roadways in some areas. To solve this problem, cement fly-ash gravel (CFG) piles are used to control settlements because of their simple construction. Sheet piles, which are mainly used in railway subgrade construction, can provide greater load performance and reduce settlement. The main objectives of this study were (1) to compare the settlement-controlling performance of sheet piles and CFG piles and (2) to evaluate the application of sheet piles to highway extension engineering. To compare the treatment effect, a case study was conducted. The settlements occurring at the instrumented locations were periodically monitored through the embedded settlement plates and horizontal inclinometers. The settlements in the construction processes were continuously observed. It was found that the settlement rate in the sheet-pile area lessened after surface construction, and the settlement was much smaller than that in the CFG-pile area, even though the initial settlement in the sheet-pile area was larger than that in the CFG-pile area before surface construction. The results suggest that the sheet pile has a significant effect on total and differential settlement control in extension construction. The insights in differential settlement indicate that the sheet pile could improve the subgrade bearing capacity and strengthen the stability of the embankment. Sheet piles could be one of the favorable ground-improvement methods to treat the settlement in highway extension constructions when the construction time and deformation are strictly restricted.

Ballistic and snake photon imaging for locating optical endomicroscopy fibres.

We demonstrate determination of the location of the distal-end of a fibre-optic device deep in tissue through the imaging of ballistic and snake photons using a time resolved single-photon detector array. The fibre was imaged with centimetre resolution, within clinically relevant settings and models. This technique can overcome the limitations imposed by tissue scattering in optically determining the in vivo location of fibre-optic medical instruments.

Deformation evaluation on surrounding rocks of underground caverns based on PSO-LSSVM

To evaluate the deformation of surrounding rocks of the underground caverns in the Xiangjiaba hydropower station during excavation, a least squares support vector machine (LSSVM) method based on particle swarm optimization (PSO) algorithm is proposed in this study. The PSO algorithm was employed in optimizing the regularization and kernel parameters of the LSSVM. To develop the proposed PSO-LSSVM model, several important factors, such as the geological conditions, location of monitoring instruments, space and time condition before and after measuring, were used as the input parameters, while the displacement of surrounding rocks was the output parameter. Further, the numerical results of the deformations of surrounding rocks were compared with the measured data. The results obtained demonstrate that the proposed PSO-LSSVM model has potential in accurately forecasting the deformation of surrounding rocks of underground caverns subjected to excavation.

Prevention of Proximal Junctional Kyphosis: Are Polyaxial Pedicle Screws Superior to Monoaxial Pedicle Screws at the Upper Instrumented Vertebrae?

Evidence regarding whether the polyaxial pedicle screws at the upper instrumented vertebrae (UIV) are superior to monoaxial pedicle screws in prevention of proximal junctional kyphosis (PJK) is not clear. The aim of this study was therefore to explore the influence of different types of pedicle screws at UIV on the incidence of PJK. We reviewed retrospectively 242 patients surgically treated with instrumented segmental posterior spinal fusion at a minimum of 4 motion segments. Polyaxial pedicle screws were used at UIV in 125 patients (polyaxial group), and monoaxial pedicle screws were used at UIV in 117 patients (monoaxial group). According to the occurrence of PJK at final follow-up, patients in both the polyaxial and monoaxial groups were then divided into 2 subgroups: PJK and no proximal junctional kyphosis (NPJK). To investigate the risk factors of PJK, 2 categorized variables were analyzed statistically: 1) patient characteristics: age, sex, body mass index (BMI), bone mineral density (BMD), sagittal vertical axis (SVA), thoracic kyphosis, thoracolumbar junctional angle, lumbar lordosis (LL), pelvic incidence, pelvic tilt, and sacral slope. 2) Surgical variables: Changes of radiographic parameters include the SVA, thoracic kyphosis, thoracolumbar junctional, LL, pelvic incidence, pelvic tilt, sacral slope, pedicle-upper end plate angle, the number of instrumented levels, and the most proximal and distal levels of the instrumentation. PJK was developed in 26 of 117 patients (22.2%) in the monoaxial group and 30 of 125 patients (24.0%) in the polyaxial group. Until the final follow-up, there was no significant difference in the incidence of PJK (χ2= 0.107, P= 0.734) between the monoaxial and polyaxial groups. There was no significant difference in patient characteristics and surgical variables between the 2 groups, except the proximal junctional angle change (P= 0.031). In the monoaxial group, there were no significant differences in patient characteristics between the PJK and NPJK subgroups, except BMI (P= 0.042) and BMD (P= 0.037). There were no significant differences in change of radiographic parameters, except SVA change (P= 0.036), proximal junctional angle change (P= 0.029), LL change (P= 0.025), and lower instrumented vertebrae location (P= 0.036). Multivariate logistic regression analysis revealed that obesity, osteoporosis, lower instrumented vertebra at sacrum, and LL change >10 degrees were independently associated with PJK. In the polyaxial group, there were no significant differences in patient characteristics between the PJK and NPJK subgroups, except BMI (P= 0.032) and BMD (P= 0.040). There were no significant differences in change of radiographic parameters between the PJK and NPJK subgroups, except P-UP angle (P= 0.037) and lower instrumented vertebrae location (P= 0.017). Multivariate logistic regression analysis revealed that obesity, osteoporosis, and lower instrumented vertebra at sacrum were independently associated with PJK. Polyaxial pedicle screws at UIV is not superior to monoaxial pedicle screws in prevention of PJK. Obesity, osteoporosis, and lower instrumented vertebra at sacrum are risk factors for PJK in all the patients. Excessive LL reconstruction is the unique risk factor of PJK when monoaxial pedicle screws were used at UIV.

Momentum transfer under laboratory wind waves

In this study, we explain contradictory previous observations of the contribution of coherent wave organised motion to the downward transfer of momentum through wave Reynolds stresses (ρu˜w˜¯) below wind waves. The generation of non-zero u˜w˜¯ is potentially significant because 1) the turbulent mixing is not then the only momentum transport mechanism under wind waves as was previously assumed, 2) this provides a wave-current energy exchange pathway that could explain inconsistencies in measured air- and water-side wind-wave energy transfer and 3) it can be a critical term in the wave-current coupling formulation under wind waves. However, such a mechanism for momentum transfer has generally been ignored, since contradictory observations were reported. Here, two new sets of wind-wave laboratory experiments are reported. For the first set, contradictory u˜w˜¯ were observed, as in previous literature. Investigating the sources of such inconsistency, we examined spatial inhomogeneity due to wave reflection through a second set of experiments, by varying instrument location and additionally considering random waves. The results resolve the inconsistencies observed in the first set of experiments and previous measurements. In addition, we emphasise the contribution of secondary circulation cells in momentum transfer under wind waves.