Reference Plane Research Articles

A novel method using 3D CBCT to assess anterior malar prominence among native Bangalore population- A descriptive study

There is a lack of accurate three-dimensional studies to locate malar prominence for specified population, this study aims to locate the malar prominence using stable landmarks using CBCT. To derive a novel method to accurately locate the malar prominence and to assess and compare the malar prominence between males and females among Bangalore population using 3D CBCT study. All CBCT scans of study subjects belong to Bangalore population were collected from the pre-existing data available in Radiology imaging Solutions (CBCT centre), Bangalore during the period of September 10th to October 10th 2020. This is a descriptive study. A total of 42 subjects including 21 Males and 21 females were assessed using full skull CBCT scans which were converted to DICOM format and reconstructed into 3D images using NEMOCEPH 3D software. Landmarks used to locate the malar prominence were Fzs, Z, Zm and Ans. The intersection of these landmarks is considered to be as constructed maxillozygion(My). For the accuracy of the constructed Maxillozygion point (My), the distance between the actual Maxillozygion (Mzy) and constructed Maxillozygion (My) is measured and calculated between left and right halves of males and females. Three Orthogonal planes constructed were Midsagittal, Axial and Coronal Planes and the linear measurements with reference to all three reference planes in both the groups are measured. Student paired t- Test, Independent Student t Test, Mann Whitney Test. The mean distance from Mzy and my between right and left half of the face was compared using student paired t- Test. There is no significant difference (p=0.35).The mean values of the constructed anatomical landmark (maxillozygion) coordinated to three orthogonal planes between right and left sides of the face is compared using student paired T test and for both the genders (males and females) was compared using Independent Student t Test, and it is significantly higher in males as compared to females and it is statistically significant at (p=0.01). The location of malar prominence using CBCT by a novel method for Bangalore population is found which can be helpful in diagnosis and treatment planning for malar augmentation, camouflage treatment in subjects with midface deficiencies.

A numerical study on near-field pressure fluctuations of symmetrical and anti-symmetrical flapping modes of twin-jet using a high-resolution shock-capturing scheme

Screeching supersonic jets appears at off-design operating conditions and is perceived as an intense tonal noise. In a twin nozzle configuration, mutual interactions between the two jet plumes may occur with various coupling modes developing depending on the operating conditions and lateral distance between the jets. The investigation of the detailed flow behaviors and near-field pressure fluctuations with relevance to the twin jets system, the analysis of the developed instabilities, will enhance understanding of fundamental features associated with jets located close to each other.In the present study, the single jet is considered first to assess the large eddy simulation (LES) approach used and the near-field pressure fluctuation predictions. Based on the validated solver, twin jets are simulated. Two different twin-nozzle configurations having different separation distance or nozzle-to-nozzle centerline spacing are scrutinized for the same Mach number of 1.358. Notably, the twin jets are screeching by the coupling mode for both set-ups; however, the case of closer inter-nozzle distance presents a symmetrical dominant flapping mode, while the other case shows an anti-symmetrical flapping mode. The strength of the pressure fluctuation at the fundamental frequency changes depending on the location of the observer point (upstream or downstream) and the reference plane (twin-jet and normal to the twin-jet plane). The screech tones of the two cases, observable in the upstream region, are significantly different in the normal to the twin-jet plane direction because of the phase difference of fluctuating pressure. However, the first harmonic component remains strong, regardless of the flapping mode. It is also observed that, at the fundamental frequency, the amplitude of the pressure fluctuation at downstream locations is found to be strong in the normal to the twin-jet plane when the symmetrical flapping mode occurs. This feature is also observed in the twin-jet plane in the case of the opposite mode. By analyzing the developed vertical structures and performing correlation analyses of pressure fluctuations along jet shear layers, the periodicity of the flow in the downstream region with relevance to the fundamental frequency is revealed.

Uncertainty determination of a microvolume characterized through confocal microscope technique

Standardized measurements protocols are widely used and necessary in order to ensure a relivable and repetitive data. This work introduces a new procedure to measure the volume of any irregular micro-hole on a rough surface. A filtering and fitting model is proposed for calculating the void volume of the cavity. Experimental point cloud is acquired by optically measuring the micro-hole with a confocal microscope. RANSAC algorithm is used to establish the reference plane, while the limits of the cavity and the volume are determined by a proposed algorithm. The mentioned model is validated by measuring six real samples. In addition, the corresponding uncertainty is estimated by using Monte Carlo method.

Development of the scheme and method for measuring the characteristics of the friction areas in the car wheel contact

The aim of the research is to develop and implement a scheme and method for measuring the characteristics of static and sliding friction areas in the contact patch of an elastic wheel with a solid support when they appear, exist and disappear. The characteristics are understood as: the relative location of static and sliding friction in relation to the vector of the translational speed of the wheel axis; their size and location in the contact patch when they appear, spread and disappear; the values of the moments on the wheel, corresponding to the appearance, spread and disappearance of static and sliding friction. A scheme and a method for measuring these characteristics have been developed and implemented. The measurements are indirect. It has been experimentally established that, in the general case, the geometric center of static friction in the contact patch moves towards the moment acting in the plane of the wheel rotation relative to the rotation axis by an amount proportional to the moment. The maximum value of this displacement according to the moment that is maximum in terms of sliding conditions, and is one third of the contact patch length for all types and conditions of a solid support. The research results are valid for elastic wheels with a radial stiffness not exceeding 12000000 N/m, the main plane of which is perpendicular to the reference plane. The research results can find application in design modeling of stability and controllability of vehicles.

A Posterior-Anterior Cephalometric Study of Skull Symmetry in Patients With Neurofibromatosis Type 1.

Neurofibromatosis type 1 (NF1) is a tumor predisposition syndrome. Bone findings make a significant contribution to the clinical diagnosis of NF1. It has been suggested that there are characteristic skeletal features of the NF1 patients' skull that cause a specific 'NF1 facies'. To test this thesis, skull examinations were carried out on NF1 patients. The posteroanterior (PA) cephalograms of 76 patients with NF1 were analyzed using defined measuring points. Patients with confirmed facial plexiform neurofibromas (PNF) were excluded from the study. A special interest of the investigation was the symmetry of the measuring points defined as the distance to the median sagittal plane. NF1 patients have a slightly larger distance to the Z-plane than controls at the zygomatic arch and mastoid measurement points (p=0.027 and 0.028, respectively). In contrast, the distances of the juga and antegonion measurement points from the horizontal reference plane are larger in the control group (p=0.002 and 0.480, respectively). The transverse development of the midface at the level of the zygomatic arch showed no differences from the control group (p=0.841). The transverse diameter of the skull at the mastoid and juga measurement points is smaller in the NF1 group compared to the control group (p=0.010 and 0.002, respectively). There is a statistically significant left-right (LR) asymmetry of the distances to the median sagittal plane in favor of the left side in the patient group (p=0.002 to 0.037). However, the numerical deviations from the control group are small overall. Considering the natural, biological deviations of cephalometric measurements of the individual from idealized geometric norms, the facial skeleton of NF1 patients is symmetrically developed. It is unlikely that the calculated LR asymmetry of the patients has a visible effect. In comparison to cephalometric values of a normal population, no characteristic facial skeleton of the NF1 patient in the PA projection of the skull can be derived from these findings. Clear asymmetries of the facial skeleton should give rise to further diagnosis to clarify the suspicion of facial PNF.

Blade pitch and air-outlet width effects on the airflow generated by an airblast sprayer with wireless remote-controlled axial fan

The airblast sprayers are equipped with a fan generating an air stream that helps the sprayed droplets to reach out and penetrate the tree canopy. Recently an automatic air regulation system has been developed and integrated in an airblast sprayer equipped with a conventional axial fan (900 mm diameter). This system, thanks to a wireless connection between a dedicated tablet and sprayers actuators, allows to remotely control the blade pitch and the air-outlet section, varying the characteristics of airflow generated by the fan. Therefore, the present work aims to characterize the different air streams derived from the combination of two fan outlet section widths (110 and 150 mm) and three blade pitches (20°, 25° and 30°). For each combination, the three components of air velocity (m s−1) were measured, taking as reference the plane following the theoretical trajectory of the main current leaving the fan. In this plane, velocities were measured at 1.0, 3.0, 5.0 and 10.0 m from the outlet section on both sides of the sprayer. At each distance, the velocities from 0.25 to 4.00 m in height were recorded. This same procedure was repeated in two planes parallel to the reference plane, 0.30 m behind and after respectively. Additionally, the velocities in the fan outlet section were also measured to obtain the airflow rate. In general, the outlet section and the blade pitch had a significant effect on the velocity components. An outlet section of 110 mm meant a smaller airflow rate and a higher initial velocity, while with 150 mm the airflow rate reduced and the initial velocity decreased. Velocities could be bigger by enhancing the blade pitch. The turbulence intensity was similar at 1.0 m distance in all cases.

Application of a three-dimensional virtual model to study the effect of fluoroscopic angle on infra-acetabular corridor parameters and screw insertion rates

PurposeTo use three-dimensional (3D) virtual models to study how the parameters and insertion rates of the infra-acetabular corridor (IAC) change under different fluoroscopic angles.MethodsThe pelvis computed tomography data of 187 patients are imported into Mimics software in DICOM format to generate a 3D model. The anterior pelvis plane is used as the reference plane to measure the diameter of the optimum IAC when the pelvis model is tilted forward by 5°, 15°, 25°, 35° and 45°. The diameter of at least 3.5 mm is defined as the cutoff for placing a 3.5 mm screw, the rate of infra-acetabular screw (IAS) insertion is calculated, and the mean length of the IAC and the mean tilt of the corridor axis in relation to the sagittal midline plane (SMP) are measured.ResultsThe similar diameters of the IAC can be found under fluoroscopy at 5°–35°, with the largest diameter of 4.08 ± 1.84 mm and the highest screw insertion rate of 60.42% at 15° and 25°, whereas the diameter and insertion rate are lowest at 45°. The corridor length increases with increasing fluoroscopic angle, and the angle of the corridor axis to the SMP decreases gradually.ConclusionThe conventional fluoroscopic angle of the pelvic inlet is not suitable for the IAS insertion. The parameters of the IAC vary according to a certain rule under different fluoroscopic angles, so a surgeon can select the appropriate fluoroscopic angle in accordance with the type of fracture and the fracture line angle.

Microstrip Impedance Management through Multilayer PCB Stack-Up: Discontinuity Compensation Voids with Asymmetric Dielectrics

To process high-frequency signals on a printed circuit board (PCB), it is often necessary to carefully analyze and select the pad widths of the chip packages and components to match their impedance to the standard Z0. Modern PCBs are complex multilayer designs, utilizing either only high-end laminates, low-end laminates, or a combination of both. The on-board component footprints usually have larger pads that become discontinuities and corrupt the impedance of critical traces. One way to address this issue is to include reference plane cutouts as a measure of compensation. This paper aims to find out how an asymmetric dielectric stack-up affects the microstrip discontinuity impedance compensation using reference plane cutouts. The selected board layer stack-up imitates several different practical design scenarios, including costly PCBs that strictly comprise high-end dielectric materials, as well as trying to lower PCB cost by introducing low-cost materials without major performance sacrifice. S-parameter measurements are performed and confirmed by time domain reflectometry (TDR) measurements.

Mandibular Stability After Sagittal Split Ramus Osteotomy With Hybrid Technique in Asymmetric Patients.

The hybrid technique after bilateral sagittal split ramus osteotomy is an internal fixation method using monocortical mini-plates and additional bicortical positional screws. In this study, we analyzed the postoperative stability of 23 patients with mandibular asymmetry who underwent bilateral sagittal split ramus osteotomy and hybrid fixation with or without LeFort I osteotomy. Anatomical landmarks of the deviated and non-deviated sides of the jaw were established to measure the angle and distance to the reference plane in three-dimensional cone beam computed tomography images. We analyzed the positional changes and correlations of the reference points at preoperative (T1), postoperative 2 weeks (T2), and postoperative 1 year (T3). There were significant differences in preoperative position of the upper and lower molar cervix alveolar crest to the reference plane (U6-X and L6-X) and the condylion angles between deviated and non-deviated sides. Postoperatively (T2-T3), each reference point had no statistically significant positional change. Pearson correlation coefficient between the amount of menton deviation (ME-X at T1) and positional change of menton after surgery (T2-T3) was 0.30, and P value was 0.168. The hybrid fixation technique is an effective fixation method for achieving postoperative stability for mandibular asymmetry.

Static, buckling and free vibration analyses of composite sandwich plate with bi-directional trapezoidal cores using VAM-based reduced plate model

The geometry of the composite sandwich plate with bi-directional trapezoidal cores (BTCs) is characterized by its novel cores with trapezoidal convex and concave corrugations in two in-plane directions. To solve the related difficulties in mechanical problems, a reduced plate model is established and written as a variational formulation based on the variational asymptotic method (VAM). That is, the original 3D plate problem was reduced to unit cell analysis (providing effective plate properties, such as the A, B, and D matrices) and two-dimensional (2D) reference plane analysis. To validate the accuracy and effectiveness of the reduced plate model, we analyze the static displacement, global buckling, and free vibrations of the composite sandwich plate with BTCs under different boundary and load conditions. Finally, we investigate the influence of the layup configurations of the face sheet and geometric parameters of the BTCs on the effective plate properties, buckling loads, and natural frequencies of the plate, which can provide useful reference for the structure optimization of composite sandwich plate with BTCs.

Systematic Approach for Tunnel Deformation Monitoring with Terrestrial Laser Scanning

The use of terrestrial laser scanning (TLS) point clouds for tunnel deformation measurement has elicited much interest. However, general methods of point-cloud processing in tunnels are still under investigation, given the high accuracy and efficiency requirements in this area. This study discusses a systematic method of analyzing tunnel deformation. Point clouds from different stations need to be registered rapidly and with high accuracy before point-cloud processing. An orientation method of TLS in tunnels that uses a positioning base made in the laboratory is proposed for fast point-cloud registration. The calibration methods of the positioning base are demonstrated herein. In addition, an improved moving least-squares method is proposed as a way to reconstruct the centerline of a tunnel from unorganized point clouds. Then, the normal planes of the centerline are calculated and are used to serve as the reference plane for point-cloud projection. The convergence of the tunnel cross-section is analyzed, based on each point cloud slice, to determine the safety status of the tunnel. Furthermore, the results of the deformation analysis of a particular shield tunnel site are briefly discussed.

Numerical formulation for nonlinear analysis of concrete and steel shells with deformable connections

A two-dimensional interface finite element capable of associating flat shell elements positioned one above the other was developed. The implemented interface element can physically simulate the contact between the flat shell elements and connect the reference planes of the shell elements above and below it. The formulation presented allows consideration of nonlinear behavior for the deformable connection as well as for the concrete and steel materials that make up the shell structure. One of the practical applications analyzed in this research is the numerical simulation of composite floors formed by a reinforced concrete slab connected to steel beams through a deformable connection. In this case, the concrete slab and the steel beams are discretized by flat shell elements and the deformable connection is discretized by two-dimensional interface elements. Experimental and numerical results from literature were used to validate the implemented elements. In the two examples analyzed, the results obtained for the displacements were close, with the difference, in the first case, being associated with uncertainties during the experimental test and in the second, the difference in theories used in the formulation of the implemented elements.

A Novel 3-Way Dual-Band Doherty Power Amplifier for Enhanced Concurrent Operation

This article presents the architecture and design methodology for a new type of dual-band Doherty power amplifier (DB-DPA), referred to as 3-Way DB-DPA, which consists of a main amplifier for each band and an auxiliary amplifier handling both bands. The 3-Way DB-DPA improves the average drain efficiency in concurrent dual-band operation compared to the traditional 2-Way DB-DPA, by avoiding early clipping in the main amplifiers, while benefiting from load—pulling from the auxiliary power amplifier (PA). This improvement is verified in theory and simulation at the current-source reference planes and in measurement with a fabricated 1.5- and 2-GHz dual-band PA. A statistical analysis using 2-D continuous-wave (CW) signals with long-term evolution (LTE) probability distribution functions (PDFs) is performed and demonstrated an improvement in the concurrent average efficiency by 15 percentage points compared to the conventional 2-Way DB-DPA. In nonconcurrent operation, the measured CW drain efficiency in the lower band (1.5 GHz) is 82.8% at peak and 66.6% at 9.6-dB backoff, and the measured CW drain efficiency in the upper band (2.0 GHz) is 70.0% at peak and 48.4% at 9.4-dB backoff. The CW concurrent-balanced drain efficiency reaches 66.2/52.0% in the 3-Way DB-DPA at 3-/6-dB backoff. In single-band operation at 1.5/2.0 GHz, the average power and average drain efficiency after linearization by digital predistortion (DPD) are 35.1/37.4 dBm and 65.0/53.7%, respectively, for an LTE signal with 10-MHz bandwidth and 6.1-dB peak-to-average power ratio (PAPR). In concurrent operation, the 3-Way DB-DPA is driven by two 10-MHz LTE uncorrelated signals at 1.5 GHz with 6.86-dB PAPR and at 2.0 GHz with 6.26-dB PAPR, and the average total power and average concurrent drain efficiency after DPD are 37.5 dBm and 54.24%, respectively.

Количественная оценка скорости коррозии металлических материалов с помощью конфокальной лазерной сканирующей микроскопии

This study represents an alternative method for quantitative estimation of the corrosion rate of various metallic materials, in particular magnesium and its alloys, using confocal laser scanning microscopy (CLSM). This method makes it possible to obtain not only optical images of the specimen surface, but also accurate 3D height maps which allow a quantitative assessment of many characteristics such as surface profile, damage locality, number and maximum depth of corrosion pits, volume of metal loss and corrosion products. Specific methodological aspects and possibilities of using the CLSM method for the analysis of corrosion damage have been described. The proposed method is based on obtaining 3D images of the surface of specimens after corrosion tests with their subsequent processing and analysis, with the use of original software computer procedures for digital image processing and topographic data arrays. A technique for recording and subsequent analysis of specimens after corrosion tests using CLSM has been developed and tested. The optimal magnification, lens type, scanning step and noise filtering have been determined. The procedure prescribes mounting the test metallic sample into a non-corrosive material to create a stable reference plane surface. The dissolution of the metal at the specimen-mount interface is found to be notably more intensive than in the specimen interior when the conventional metallographic resins are used as the mount. This fact deteriorates the objectivity of the results of corrosion rate measurements. Polyethylene is proposed as the mounting material to minimize this effect. The geometry and the minimum size of the metal sample, providing a reduction in labor contribution for scanning and data processing without loss of accuracy and reliability of the data are established. The values of the uniform corrosion rate of commercially pure magnesium in Ringer's solution using the gravimetric method and the CLSM method showed satisfactory repeatability of measurements.

Substantiation of the presence and parameters of seed guides in the openers, which increase the quality of sowing and yield

One of the promising methods for improving the uniformity of seed distribution in the soil is the control of the grain flow by guiding elements in the openers. This creates favorable conditions for the flight of seeds in the openers and when leaving them backwards, which equalizes the speed, in modulus, of seeds and the unit, improves the uniformity of their distribution in the soil. The presence and parameters of the guiding elements of the openers was theoretically substantiated, which gave the development of the process of controlling the grain flow in the openers and at the exit from them by using the guiding elements. Analytical expressions have been obtained to determine the characteristics of the movement of particles on various surfaces, which are recommended to be used for guides in the openers. Experimental studies have shown that openers with guides reduce the coefficient of variation along the row by 20 ... 45% and have it 88 ... 98%, and in depth - 24 ... 27%. On the basis of experiments, it is recommended that 3 ... 4 guides are recommended for front openers (arithmetic mean interval along the row 18.5 ... 23.5 mm, coefficient of variation 88 ... 98%). The advantage of the experimental opener in the distribution of seeds by depth is due to the use of guide elements in combination with an improved soil shedding process. This eliminated the technological drawback - the formation of a sub-opener inclined surface (arithmetic mean interval 42 ... 37 mm, coefficient of variation 24 ... 27%). For a double disc opener, an improved guide is recommended, the bottom edge of which protrudes 2 cm in front of the vertical diameter of the discs and is located at a distance of 9 cm from the reference plane. The arithmetic mean spacing along the row of this opener is 15 mm, the coefficient of variation is 106%.

Identifying cortical plate inclination as a parameter to re-assess transverse discrepancies in untreated adults with different vertical facial heights-A retrospective CBCT study.

To determine the inclination angles of buccal, palatal cortical plates and assess its harmony with existing molar buccolingual inclination in adults with different vertical facial heights. The aim of this study was to identify the role of cortical plate inclination as a diagnostic tool for determining alveolar support in adults with transverse discrepancies. One-hundred and fifty seven CBCTs (50-Hypo-divergent, 51-Normo-divergent and 56-Hyper-divergent growth patterns) of untreated adults were utilized. Cross-sectional slices with respect to the maxillary first molar were taken as orientation landmarks in defined reference planes. Inclination angles for the first molar, buccal and palatal cortical plate were determined with respect to the palatal plane. ANOVA and Post Hoc Tukey's HSD test were carried out to determine significant differences between groups. Molar inclination was significantly greater in hyper-divergent groups compared to normo-divergent and hypo-divergent groups (P<.05). Greater variation between molar inclination and cortical plate inclination (buccal and palatal) was seen in hyper-divergent groups (P<.05). Hypo-divergent and normo-divergent groups showed almost similar molar and cortical plate inclinations; however, there was a significant difference between the buccal and palatal cortical plates (P<.05). Cortical plate inclination is in agreement with molar inclination in hypo- and normo-divergent groups when compared to hyper-divergent groups. In adults with decreased/normal facial heights, greater balance and harmony is observed between the dental and alveolar substructures in the posterior region. In adults with increased facial heights, a greater amount of dentoalveolar compensation is seen with respect to the molar and its surrounding bone support.

Material-Specific Optimization of Gaussian Basis Sets against Plane Wave Data.

Since in periodic systems, a given element may be present in different spatial arrangements displaying vastly different physical and chemical properties, an elemental basis set that is independent of physical properties of materials may lead to significant simulation inaccuracies. To avoid such a lack of material specificity within a given basis set, we present a material-specific Gaussian basis optimization scheme for solids, which simultaneously minimizes the total energy of the system and optimizes the band energies when compared to the reference plane wave calculation while taking care of the overlap matrix condition number. To assess this basis set optimization scheme, we compare the quality of the Gaussian basis sets generated for diamond, graphite, and silicon via our method against the existing basis sets. The optimization scheme of this work has also been tested on the existing Gaussian basis sets for periodic systems such as MoS2 and NiO, yielding improved results.

Orthodontic Assessment of Lip Prominence in Pakistani population

Introduction: Many reference planes are being used to determine prominence of upper and lower lip for orthognathic face profile. E-line and S-line are being used to determine lip position in local popuation of Multan city of Pakistan. Materials and Method: Execution of present study was done in Nishtar Institute of Dentistry, Multan during the period of November 2019-March 2020. 300 (112 Males and 188 Females) subjects were selected for this study from all provinces of Pakistan. Their radiographic records (Lateral cephalograms) were taken from radiographic department of related institution. Acetate matte sheets were used to construct reference planes by using 3H pencil. Steiner’s E-line and Rickett’s S-line were used to find Upper and Lower lip position from these reference lines. SPSS was used to analyze data after applying independent t-test. Result: Mean Upper and lower lip position from E- line was -1.74mm &amp; -0.33mm and from S-line was 0.82mm and 1.47mm Conclusion: Cephalometric lip morphology assessment in Multan, Pakistani adults by using Steiner’s and Rickettsreference planes on lateral cephalogram is slightly different as compare to other populations

123. A novel comprehensive model to describe vertebral body motion following interbody fusion

<h3>BACKGROUND CONTEXT</h3> Subsidence of interbody fusion spinal implants occurs in up to 30% of interbody fusions. Previous methods to quantify subsidence of interbody implants have focused on quantifying changes in disc height or magnitude of erosion of the implant into the vertebral body. These studies focus on the description of subsidence in a cranial-caudal direction. A comprehensive description of subsidence should report cranial-caudal shift, anterior-posterior shift and angular shift of one vertebra with respect to its adjacent vertebra. <h3>PURPOSE</h3> The purpose of the study is to develop and validate a novel method that describes the motion of one vertebral body with respect to its adjacent vertebral body in terms of translation and rotation. We hypothesize this method would have satisfactory interobserver reliability. <h3>STUDY DESIGN/SETTING</h3> Retrospective review of lumbar spine radiographs at a tertiary academic center. <h3>PATIENT SAMPLE</h3> Patients undergoing anterior lumbar interbody fusion at L4-5 or L5-S1 with at least one year radiographic follow-up. <h3>OUTCOME MEASURES</h3> The amount of cranial-caudal shift, anterior-posterior shift and angular shift on preoperative, postoperative, and 1-year postoperative radiographs was recorded according to the novel measurement technique. <h3>Methods</h3> A retrospective review of lateral lumbar spine radiographs was performed by seven physicians (3 residents, 2 fellows, and 2 attendings). The review included radiographic analysis of 10 patients who underwent L4-5 or L5-S1 anterior interbody fusion. Preoperative, postoperative (day 1), and 12-month postoperative radiographs were analyzed. Each vertebra was defined in two-dimensional space by 4 peripheral points at the corners of the vertebral body and a centroid. The upper vertebra was designated as a reference plane by which the motion of the lower vertebra was measured. We measured the movement of the lower vertebra in terms of anterior-posterior translation, cranial caudal translation, and angular change immediately following lumbar interbody fusion and 12 months postoperatively to detect translational and rotational subsidence. Inter-observer reliability was measured using SPSS software. <h3>Results</h3> A model was successfully developed to describe the angular and translational change of one vertebral body with respect to its adjacent segment. The intraclass correlation coefficients of anterior-posterior, cranial-caudal, and angular change were calculated to be 0.75, 0.90, and 0.86, respectively. The average standard deviations of translational and rotational change were 3.3% and 2°, respectively. <h3>Conclusions</h3> A model to comprehensively describe vertebral body motion as a method of characterizing subsidence was successfully developed. The model had good to excellent reliability. Further refinement of the protocol may yield improved intraclass correlation coefficients. This method of measuring vertebral body motion is applicable to measuring modes of failure beyond subsidence such as fracture or delayed fusion. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.

A New Ground-Based Pseudolite System Deployment Algorithm Based on MOPSO.

Pseudolite deployment is the premise of ground-based pseudolite system networking, which affects the coverage and positioning accuracy of ground-based pseudolite systems. Optimal deployment algorithms can help to achieve a higher signal coverage and lower mean horizontal precision factor (HDOP) with a limited number of pseudolites. In this paper, we proposed a multi-objective particle swarm optimization (MOPSO) algorithm for the deployment of a ground-based pseudolite system. The new algorithm combines Digital Elevation Model (DEM) data and uses the mean HDOP of the DEM grid to measure the geometry of the pseudolite system. The signal coverage of the pseudolite system was calculated based on the visual area analysis with respect to reference planes, which effectively avoids the repeated calculation of the intersection and improves the calculation efficiency. A selected area covering 10 km×10 km in the Jiuzhaigou area of China was used to verify the new algorithm. The results showed that both the coverage and HDOP achieved were optimal using the new algorithm, where the coverage area can be up to approximately 50% and 30% more than using the existing particle swarm optimization (PSO) and convex polyhedron volume optimization (CPVO) algorithms, respectively.