Lateral Limit Research Articles

A Workshop-Based Evaluation of a Tool for Online Feedback During Contouring

<h3>Purpose/Objective(s)</h3> Inter-observer variability (IOV) in target volume delineation is one of the largest sources of uncertainty in radiotherapy. It can be reduced by following guidelines and training, but the effects of training fade over time. Our aim was to evaluate a tool that provides automatic feedback during delineation and its impact on breast and lymph node IOV, using contouring workshops. <h3>Materials/Methods</h3> Automatic online feedback was presented via warning annotations displayed on the delineated contours when the observer crossed medial, lateral and skin limits. These limits were generated based on a machine learning solution that learnt guideline limits from 150 expertly contoured cases. Warning annotations were also shown when the users were using incorrect local window/level settings, based on analysis of the displayed grey values close to the contour. The system was tested in two 2-day contouring workshops (WS1, WS2). During WS1, we assessed acceptability of the tool via qualitative feedback. Prior to WS2, participants were asked to contour two cases (breast and lymph nodes). During the first day, training was provided on breast delineation following international guidelines. The participants then delineated two additional cases. The final day included additional training, discussions, and general feedback. For each workshop, the tool was enabled for one case. To evaluate IOV, the standard deviation (SD) of the perpendicular distances from every point on each observer's contour to the median of the contours was calculated. SDs for the cases with/without feedback were compared pairwise per observer and volume. We report changes in SD before and after training, and defined <i>improvement</i> when SD reduced by >2mm. <h3>Results</h3> Feedback after WS1 showed acceptability of the tool and its potential to influence observers even with minimal training. In WS2, 10 participants, out of 16, delineated all cases (138 contours). Training improved consistency in 23% of analyzed contours for cases when the tool was disabled, and only in 14% when the tool was enabled. SD changes <2mm were 63% for both cases. <h3>Conclusion</h3> Real-time automated feedback during contouring is feasible and has the potential to reduce IOV. Our results suggest that it can have similar effects to training. Its use for day-to-day contouring could act as a permanent reminder of guidelines, which may mitigate the fading effect seen after training. This could help to improve contouring by automatically providing anatomical limits to clinically defined target volumes and promoting correct window-level usage.

The Limit of the Lateral Fundamental Frequency and Comfort Analysis of a Straddle-Type Monorail Tour Transit System

The straddle-type monorail tour transit system is a light overhead steel structure, and the lateral stiffness is generally low. However, the limit of the lateral natural vibration frequency is not clear in the current codes of China, and designers may ignore it. Weak lateral stiffness will lead to a violent vibration during vehicle operation and crowds walking, affecting human comfort and structural safety. Based on a practical project, we tested the acceleration of a monorail vehicle under full load conditions, and its running stability and ride comfort were assessed. Then, the impact of pedestrians on lateral vibration under some working conditions was measured and analyzed. Furthermore, the influence of different structural parameters on the lateral fundamental frequency was investigated. The results showed the following: (i) The vehicle’s running stability and riding comfort was good. However, human comfort was poor due to the weak lateral stiffness of the structure, which was affected by human-induced vibration. (ii) The comprehensive response of the structure increased with the increase in walking frequency, increased with the increase in the number of people working or weight, and the growth speed slowed down. (iii) The structural stiffness was most sensitive to the change in steel column diameter. (iv) The recommended value of the lateral fundamental frequency limit for different spans of the straddle-type monorail tour transit system was put forward. The recommended lower limit of fundamental frequency for a 15 m span is 5.0 Hz, for an 18 m span it is 3.5 Hz, and for a 25 m span it is 2.8 Hz.

Light Metal Alloys Local Reactivity, from AFM Based Scanning Kelvin Probe Force Microscopy (AFM-SKPFM) to Scanning Electrochemical Nanocapillary (SEN)

Materials surface heterogeneities obviously plays a crucial role in reactivity issues and generate various types of detrimental localized corrosion attacks. In corrosion science, a first question to be addressed is how these various materials microstructure affect oxidation / passivation and localized corrosion initiation mechanisms. A methodology for microscale characterization of initial stage of surface reactions has been developed based on the Atomic Force Microscopy (AFM) Scanning Kelvin Probe Force Microscopy (AFM-SKPFM). In very early work, potential mapping with micrometer lateral resolution (lateral detection limit of materials surface heterogeneities is better but the signal has to be deconvoluted) allowed to clearly identify "cathodic" and anodic sites on Al- alloys [1]. Careful potential calibration and surface conditioning with solution exposure generating the formation of an electrochemical double layer allow obtaining local thermodynamic information closely linked to "practical electrochemical potential series" measured in bulk solution conditions. This contribution will start by revisiting some "historical" examples of AFM-SKPFM characterization (a tribute to Jerry Frankel's activities) of aluminum and magnesium alloys [1,2]. These materials surfaces will further be used to show how reaction kinetic information on corrosion processes can be obtained with similar lateral resolution by means of the newly developed Scanning Electrochemical Nanocapillary (SEN) technique. After introducing the SEN technique and methodology, the presentation will focus on showing how the combination of these two approaches allows refining the local corrosion mechanism assessment of heterogeneous materials. The SEN technique is very versatile and allows various types of electrochemical measurements to be performed with constant tracking of the topography. The technique is based on a nanocapillary glass tip (< 100 nm) excited laterally by a piezoelectric element. A control of the capillary vibration damping when approaching the surface and a feedback loop (like the tapping mode in AFM) allows a very precise control of the approach and electrolyte contact on the surface. The glass capillary filled with the electrolyte of interest integrates a reference and Pt counter electrodes to perform electrochemical measurements exposing only the area of interest to aggressive electrolytes. Using its "hopping" mode (a scan with electrochemical characterization of successive individual nanoscale areas), corrosion initiation susceptibility can be addressed. This will be illustrated through the surface reactivity study of model Al-Cu-Mg microscale intermetallics and Mg-based alloys, using SEN OCP linescans. In addition information about extend of the attack can be subsequently retrieved from SEM observations. Using the precise positioning ability of the SEN setup with X, Y and Z direction piezos, potentiodynamic polarization measurements can furthermore be performed on selected area of interest. The example of an Mg-Fe composite material will be used to discuss its local electrochemical behavior.After the presentation of the SEN characterization results, additional aspects of the measured potential by AFM-SKPFM will also be discussed as adsorbed species, especially strong dipolar molecules, can significantly contribute to the measured signal [3]. Modification of the AFM-SKPFM setup towards atmospheric corrosion investigation will finally be presented. This environmental AFM/SKPFM bridges the gap between the full electrochemical local characterizations that can be offered by the SEN technique and an "electrochemical reaction" diagnostic obtained by SKPFM in thin water layer. The example of a very reactive WC-Co composite will be presented to demonstrate the reactivity issue, galvanic coupling controlling local dissolution processes [4].AcknowledgementsGerald Frankel for the great time I spent at Ohio State University in the Fontana Corrosion Center developing the AFM-based SKPFM methodology. Empa for internal project financial support of the SEN instrument.

Study on key influencing factors of competitive adsorption of coalbed methane by carbon dioxide displacement.

The extraction of coal bed methane (CBM) by injecting CO2 into deeply buried unmined coal seams in competition with CH4 adsorption to provide a clean fuel is known as enhanced coal bed methane recovery (ECBM) and has proven to be an effective technological strategy to address global warming. The study of the interaction of coal with CO2 and CH4 under multi-physical field conditions is particularly necessary. In this work, a series of experiments were conducted on a home-made test system to investigate the competing sorption patterns of high and medium ash coal samples subjected to variables such as gas pressure, temperature, nodulation and lateral limit constraints. The results show that there is a sorption isotherm relationship between coal samples and exposure time. The adsorption capacity sorption of CH4/CO2 varied considerably for different ash coal samples. As the CO2 pressure increased from 2.3 to 5.5 MPa, the strain on the coal samples increased from 0.082 to 0.4%. The deformation in the vertical laminae direction is always greater than that in the parallel laminae direction. A correlation coefficient K exists between 1 and 2, and there is an internal expansion pattern in the adsorption deformation of coal. This paper can contribute to the improvement of ECBM efficiency.

Effect of bamboo species and pre-treatment method on physical and mechanical properties of bamboo processed by flattening-densification

In this study, Dendrocalamus asper and Phyllostachys edulis (Moso) bamboo were subjected to a two-phase process of flattening and densification using a non-confined thermo-hydro mechanical (THM) system (composed of two hot plates without lateral limit) to redesign bamboo's microstructure and improve its performance for applications in panel manufacturing. Different softening procedures using pre-treatments with water under vacuum/pressure conditions using a vacuum of −650 mmHg and a pressure of approximately 3100 mmHg (V/P) and boiling treatment for 1 h at 100 °C (B) before flattening were studied. All groups were flattened, dried at room temperature, and densified at the same processing parameters. The microstructural, physical, and bending properties of the obtained flattened-densified bamboo using these two pretreatments were examined and compared with untreated-undensified (UN) bamboo and samples flattened-densified in an equilibrium moisture content (EQ). The results of bending tests, comparing to the un-processed bamboo, revealed that the flattening process combined with densification promote an average increase in the Modulus of Rupture (MOR), (56% and 66%), Modulus of Elasticity (MOE) (48% and 78%), Limit of Proportionality (41% and 86%), and Specific Energy (126% and −12%) in the case of D. asper, and Moso respectively. However, the applied process increased the thickness swelling (SW) and water absorption (WA). This negative effect was more pronounced in the case of Moso compared to D. asper. The flattened-densified Moso using any type of applied pretreatments presented an average of 64% of WA and 35% of SW, while these values for D. asper bamboo were 28% and 19% of WA and SW respectively. In addition, boiling the bamboo in water as a pre-treatment prior to densification reduces the cracks number compared to the other pre-treatments, resulting in higher MOR, MOE, and dimensional stability.

Investigation on drift ratio limits of PVA fiber reinforced concrete columns under different performance levels based on the Kunnath damage model

Within the context of the performance-based seismic design (PBSD), it is crucial to determine the drift ratio limits of PVA-FRCs under different performance levels. In this article, seven PVA fibers and high strength steel bars reinforced concrete columns were designed, and the quasi-static test was carried out to investigate their failure models and hysteretic loops. The calculated damage indexes using the Kunnath damage model were compared with the measured damage index ranges. The results indicated that the Kunnath damage model could accurately calculate the damage indexes of PVA-FRCs. According to the failure process of columns, the cracking point, yield point, peak point and ultimate point were used as the performance level control points of PVA-FRCs. Based on the idea of PBSD, the seismic performance levels of PVA-FRCs were divided into normal operation performance level, temporary operation performance level, reparable operation performance level, life safety performance level and collapse prevention performance level. Combined with the fiber concrete column test data in the references, the relative frequency statistics of the drift ratios of 38 PVA-FRCs at each feature point were carried out. The drift ratio limits under different performance levels and the corresponding damage indexes for PVA fiber reinforced concrete columns were established. Through the statistical analysis of relative frequency, the drift ratio limits of PVA-FRCs under different performance levels with more than 85% safety assurance rate were obtained, which were 1/300, 1/150, 1/80, 1/55 and 1/40, respectively. The performance level, damage state, lateral drift ratio limit and damage index were combined to form a relatively complete system to provide a reference for the anti-seismic repair of PVA fiber reinforced concrete structures.

Reliability of stainless steel frames designed using the Direct Design Method in serviceability limit states

Steel structures can be consistently and efficiently designed using system-based design-by-analysis approaches such as the Direct Design Method. However, since direct design approaches lead to potentially lighter structural configurations, they can also result in larger deformations under service loads. Thus, greater attention may be required to serviceability limit states in structures designed using design-by-analysis approaches than for structures designed elastically at their ultimate limit state following current two-stage approaches, especially for materials showing highly nonlinear stress vs strain responses such as stainless steel alloys. With the aim of investigating the influence of allowing larger deformations in the ultimate limit state design of stainless steel structures, this paper presents an explicit analysis framework for assessing serviceability reliability at system level. Using this framework, the paper investigates the serviceability reliability of cold-formed stainless steel portal frames designed using the Direct Design Method for different load cases, including the gravity load and the combined gravity plus wind load combinations. The study considers six baseline frames covering the most common stainless steel families and international design frameworks (i.e., Eurocode, US and Australian frameworks), for which the reliability of vertical deflection and lateral drift serviceability limit states is investigated using advanced numerical simulations and First-Order Reliability Methods. From the comparison of the calculated average annual reliability indices and the relevant target reliabilities for the different design frameworks, it was found that the reliability of stainless steel frames appears to be adequate for the serviceability limit states investigated for the Eurocode, US and Australian frameworks.

A TKA Insert with A Lateral Flat Articular Surface Maximizes External and Internal Tibial Orientations without Anterior Lift-Off Relative to Low- and Ultracongruent Surfaces.

Background: In total knee arthroplasty (TKA), inserts can have different levels of medial and lateral congruency determined by the acuteness of the upslopes of the anterior and posterior articular surfaces. The present study evaluated an insert with different levels of lateral congruency and a medial ball-in-socket congruency to test the hypothesis that a lateral flat (F) insert maximizes external tibial orientation at extension and internal orientation at 90° flexion and lowers the incidence of anterior lift-off relative to low-congruent (LC) and ultracongruent (UC) lateral inserts. Methods: Two surgeons treated 23 patients with unrestricted caliper-verified kinematic alignment (KA) and posterior cruciate ligament (PCL) retention. They randomly trialed inserts with a medial radial dial that functioned as a built-in goniometer by measuring the tibial orientation relative to a sagittal line on the femoral trial component. Anterior lift-off of the insert from the baseplate indicated PCL tightness. Results: The F insert’s mean of 9° of external tibial orientation was higher than that of the LC (5°, p < 0.0001) and UC inserts (2°, p < 0.0001). The −13° of internal tibial orientation at 90° flexion was higher than that of the LC (−9°, p < 0.0001) and UC inserts (−7°, p < 0.0001). The 0% incidence of anterior lift-off was less than that of the LC (26%) and UC inserts (57%) (p < 0.0001). Conclusions: Surgeons and implant manufacturers should know that adding congruency to the lateral articular surface limits external tibial orientation in extension and internal tibial orientation at 90° flexion and overtightens the PCL. These rotational limitations and flexion space tightness can adversely affect patellofemoral tracking and knee flexion.

Spatially Resolving Polymer Brush Conformation: Opportunities Ahead

AbstractSurfaces that respond to local environmental stimuli offer intriguing possibilities for new surface‐based sensing concepts to emerge. An attractive concept is to push beyond the milli‐ to micrometer lateral resolution limit in sensing, toward the ultimate surface‐sensitive device; one capable of real‐time sensing of the nanoscopic, or molecular “touch.” This sensing needs an approach that is capable of spatially transducing information on nanotouch. Polymer brushes are a class of surface that provides dramatic changes in surface properties depending on stimuli that affect the conformation of end‐tethered polymer chains. However, the brush response is typically quantified by measuring changes in polymer brush “height”. That is, the ensemble average distance over which polymer density exists away from the anchoring surface (i.e., a single parameter to describe the surface). Moving beyond this conceptual paradigm of quantifying the ensemble average height in a single dimension over the entire surface under applied stimuli, developing methods for spatially resolving chain conformation has the very real potential to lead to extraordinary possibilities in the applied sciences. In this perspective, the current paradigms and methods forward for extracting rich details on polymer brush conformational dynamics that is spatially resolved, which can lead to new understandings of surface contact, are discussed and pointed out.

The Influence of Lateral Restraining Stiffness on the Box-Girder Superstructure under Unbroken Solitary Waves

At present, box-girder superstructures are commonly used in coastal bridges, and their hydrodynamic performance under extreme waves such as tsunamis has attracted a lot of attention. There is a lack of research focusing on the effect of lateral restraining stiffness on box-girder superstructures under the extreme wave condition. In this paper, a two-dimensional numerical model based on the RANS equation and SST k-ω turbulence model is established. Combined with the dynamic mesh updating technique, the effect of lateral restraining stiffness on the superstructure of a box-girder and the dynamic characteristics of the movable box-girder under the solitary waves were investigated. To ensure the mesh quality, the numerical computational domain is divided into several regions that correspond to specific types of body motion. The numerical model is verified by comparing it with other numerical simulation results and experimental results. The dynamic characteristics and the wave forces of the box-girder superstructure under the effect of lateral restraining stiffness under the unbroken solitary waves are discussed. The results show that the horizontal and vertical forces on the box-girder superstructure under the action of unbroken solitary waves can be reduced by reducing the lateral restraining stiffness. However, with the decrease in lateral restraining stiffness, the lateral displacement of the box-girder superstructure would increase. Therefore, the lateral restraining stiffness and lateral displacement limit of the box-girder superstructure should be fully considered in practical engineering, and the appropriate lateral restraining stiffness should be selected to reduce the wave forces on the box-girder superstructure under extreme wave action, so as to improve the safety of the coastal box-girder superstructure. It is of great importance to study the interaction between the box-girder superstructure and unbroken solitary waves, which will help to have a deeper understanding to improve the disaster resistance of bridges.

Seismic Analysis on the Behaviors of Meru Structures: A Sacred Building in Balinese Temples

Seismic behaviors of the Meru structure as one of the sacred buildings in Balinese Temples have not been investigated extensively. Most research investigated the Meru building in terms of its philosophy and history. The Meru buildings were observed to survive many earthquake events that occurred in Bali Islands. This paper presents the analysis results of the Meru structure in responding to earthquake excitations. As many as five types of the Meru structure traditionally built were modeled and analyzed using finite element-based software. Each type of Meru has three variations in the roof masses that were obtained from increasing the roof thickness from 500 mm, 600 mm, and 700 mm. Time history analysis follows Newmark’s average acceleration method with an input earthquake record of the scaled El-Centro N-S 1940 to meet seismic conditions in the Bali area. The results show that the dynamic responses of the Meru structure increase as the number of roof levels and mass increase. All of the Meru types have met the limitation of the code’s lateral allowable limits. The dimensions of the structural elements determined according to Balinese scripts can provide capacity greater than twice the capacity demand. Keeping the roof mass in a certain proportion with the mass of the lowest roof twice of the above one will keep the Meru stable during an earthquake.

Three-dimensional field of view and impact angle constrained guidance with terminal speed maximization

A three-dimensional strap-down seeker based multi-constrained guidance law for an interceptor is proposed in this paper to achieve near zero miss distance with minimal control effort (lateral acceleration) and interception time. When the interceptor is guided based on strap-down seeker measurements, the field of view limit throughout the flight trajectory is one of the major concerns to guarantee tracking of the target. To enhance the capability of warhead while approaching a target, the interceptor needs to ensure the desired impact angles and maximum speed at terminal time as well as various path inequality constraints throughout the trajectory, such as lateral acceleration limit and field of view limit. To meet these requirements, the proposed guidance is designed using a new extended version of the computationally efficient, suboptimal generalized model predictive static programming (GMPSP) technique in an unspecified final time framework. In addition, to make all the states available, to estimate parameter uncertainties and to filter out the sensor measurement noises, an extended Kalman filter based state and parameter estimation is incorporated with this proposed guidance law. Using simulation studies, the efficacy of the proposed GMPSP based suboptimal guidance method is shown and compared with that of the Chebyshev pseudo-spectral method as well. The extensive simulation results also demonstrate that the proposed robust suboptimal guidance design can perform well, in the presence of aerodynamic parameter uncertainties and sensor noises.

The lower bow-shaped curve as a novel reference frame to determine the lateral limit of the maxillary anterior arch for smile esthetics

Smile analysis in horizontally angled views is indispensable for esthetic assessment and could reveal teeth-to-lip disharmony, which might escape discovery in the frontal and profile views. However, evidence is lacking on where the anterior teeth should be positioned for esthetics in angled smiles. Based on 3-dimensional facial image processing and geometric analysis, the lip edges were projected to the horizontal plane, and the horizontal teeth-to-lip relation was simplified and represented by the distances from dental landmarks to lower bow-shaped curves (LBSC), with the distance from facial-axis (FA) point of the canine to LBSC (FA-tangent line [TL] distance) identified as the key parameter. Using photographic modification and esthetic assessment, the effect of FA-TL distances on the attractiveness of 45° angled smiles was tested, with esthetic ranges identified. A simplified method was developed to obtain the estimative LBSC and FA-TL distances using 2-dimensional photographs and geometric analysis to facilitate clinical application. The FA-TL distance remarkably affected the esthetics of 45° angled smiles. Smiles were attractive when the FA-TL distance ranged from -1.0 to 1.5 mm perceived by orthodontists and from -1.5 to 1.5 mm perceived by laypersons. The 2-dimensional photograph-derived estimative FA-TL distance was not significantly different from that obtained in a 3-dimensional image, validating the simplified method. The LBSC could serve as a reference frame to determine the lateral limit of the maxillary anterior arch for the esthetics of 45° angled smiles. The FA-TL distance, which represented the spatial relation of the maxillary canine with the lower lip, was an esthetically essential parameter. For females aged 20-30 years, the FA point of the maxillary canines should be positioned no more than 1.5 mm labial or lingual to the LBSC.

Defining the limits and indications of the Draf III endoscopic approach to the lateral frontal sinus and maximizing visualization and maneuverability: a cadaveric and radiological study

PurposeThe DRAF III procedure has been used for access to the lateralmost part of the frontal sinus. We sought to identify anatomical and radiological measurements as well as modifications that predict the lateral limits of visualization and surgical access after this procedure.MethodsSeven cadaver heads were imaged with computed tomography scan. The distance from midline to the medial orbital wall (MOWD), midline to the lateral end of the frontal sinus (MLD), the sum of MLDs (SMLD), interorbital distance (IOD) and the shortest anteroposterior distance of the frontal recess (APD) were utilized. The ratios MLD/MOWD, and SMLD/IOD were calculated. The same distances were measured on 41 CT scans. Orbital transposition (OT) and partial resection of the piriform aperture (PAR) were performed; the visualization and reach were assessed. The angle of insertion was measured before and after the modifications.ResultsOnly the ratio MLD/MOWD was consistently predictive of access to the lateral, superior and posterior wall of the frontal sinus. Following the modifications, a visualization of 100% laterally was achieved with the 30- and 45 degree endoscopes and every lateral recess could be reached with the 70 degree suction. A mean increase of the angle of insertion of 25.3 and 59.6% was recorded after OT and PAR, respectively.ConclusionsIOD rather than APD defines the limits of the Draf III approach to the lateral frontal sinus and MLD/MOWD ratio can serve as a useful preoperative tool. Along to the already described OT, PAR increases visualization and reach of the lateral frontal sinus.

High-Resolution 400 GHz Submillimeter-Wave Quasi-Optical Radar Imaging System

A submillimeter-wave quasi-optical high-resolution imaging system, based on a frequency-modulated continuous wave radar sensor operating between 343GHz and 423GHz utilizing a bandwidth of 80GHz, is presented. The system setup in-tandem with the essential building blocks is described and the generation of high-resolution power- and elevation-profile images of various samples under test is presented. Experimental results show a lateral resolution limit in the order of wavelength.

The cohesive entropy of condensed materials, empirical relations and restrictions

Entropy factors of a material are connected through an equation which relates three independent experimental values specific to each material: ΔfS=S-∑inSatoms,i. (Note: our results refer to independently summed ∑1nSatoms,i values rather than calculation by simple difference of the third dependent value from the other two of these values.) We define the cohesive entropy coefficient, αScoh, through ΔfS=α∑inSatoms,i.Having ready access to a large database of thermodynamic data for solid ionic materials from earlier studies, we have investigated the generalisations that may be made among these entropy quantities for this group of materials.We find that the data points of this three-dimensional system are confined to a fan-shaped tilted plane which has rather strict lateral limits, with the upper limits controlled by the entropies of gaseous elements and the lower limits by the entropies of solid elements. This has the consequence of providing insight into the understanding of entropy values and their limits as a check on experimental determinations. In particular, formation and standard entropies for condensed phases are shown to be proportional to one another with a fixed proportionality constant, the cohesive entropy coefficient, αScoh = -0.831.Evidence is provided that the same restrictions apply to condensed organic materials, and we suggest that these entropy relations are applicable to condensed materials in general.

Off-axis electron holography: Materials analysis at atomic resolution

Abstract In high-resolution off-axis electron holography, the correction of coherent aberrations allows the quantitative interpretation of the amplitude and phase of the object wave up to the information limit of the electron microscope. Since the measured object phase is directly related to the projected atomic potential for sufficiently thin samples, off-axis electron holography is expected to allow distinguishing of different elements in the reconstructed phase image (“holographic materials analysis”). This has already been verified with the example of Ga and As. However, simulations of the atomic phase shift reveal that the interpretation of the measured phase shift in terms of atomic species is generally rather complex. The findings suggest that, in some cases, the requirements as to lateral resolution and phase detection limit will be met only by electron microscopes of the next generation.

Study on the distribution pattern of particle re-crushing in the coal and rock mass crushing process under pressure.

In order to investigate the compaction and re-crushing characteristics of crushed coal gangue with different gradation, the compaction fractal test was carried out for crushed coal gangue with different Talbol power index n. The compaction deformation parameters such as displacement, stress-strain were analyzed according to the test results. And according to the test results, the compaction deformation relationship of the lateral limit crushed coal rock body considering the gradation is obtained. The test results show that: the crushing of coal rock particles exists in almost the whole compaction process of the crushed coal rock body, and the crushing of coal rock particles has a non-negligible influence on the deformation of the whole crushed rock body; the structural stability of large-size coal rock particles is not as good as that of small-size coal rock particles, and the large-size coal rock is more likely to be crushed under the same stress conditions; the distribution coefficient r of the crushed coal rock body decreases with the increase of axial stress; and before the Before the axial stress reaches 8 MPa, the distribution coefficient r of crushed rock samples tends to increase with n in general, and after reaching 8 MPa and later, the distribution coefficient r of crushed rock samples tends to decrease with n in general; the difference value of particle crushing increases with the increase of axial stress, and the weight value of particle crushing decreases with the increase of axial stress, and the changes of both are non-linear; according to the stress recovery in the compaction process of crushed coal rock body The compaction deformation model of the crushed coal rock body is constructed according to the crushing characteristics of coal rock particles in the stage of compaction, which effectively combines its fine action mechanism with macroscopic physical phenomena in a simple form and has certain practical engineering significance.

Surface topography measurement of microstructures near the lateral resolution limit via coherence scanning interferometry

As a non-destructive method, coherence scanning interferometry is widely utilized for surface topography measurement of step microstructures in optical and integrated circuit fields. The measurements are always implemented near the lateral resolution limit of the system because the critical dimension of these microstructures is at the micron or sub-micron scale. However, in this case, not only is the image of microstructures blurred, but also the diffraction effects distort the measured topography near the step edges. The magnitude of distortion at a certain position appears to be related to its distance from the edges and the duty cycle of the microstructures. Therefore, it is necessary, although difficult, to improve the accuracy of topography measurement for microstructures if their images are blurred owing to the lateral resolution limit. When located far away from the step edges of microstructures, the coherence signals are normal and contain a single envelope with its peak corresponding to the surface height. However, the anomalous coherence signals containing two envelopes appear near the step edges. The peaks of these envelopes correspond to the top and bottom surfaces of step structures, thus distorting the coherence peak detection for topography measurement. Therefore, the primary issue is the determination of the correct envelope in the anomalous coherence signals that is achieved by distinguishing the current surface of step structures for each position. In this paper, we propose a binarization method based on edge localization to achieve surface distinguishment through the analysis of the contrast and intensity of the coherence signals. After determining the correct envelope, we construct a new form of wavelet family and employ the Morlet wavelet transform to calculate a split point for dividing the anomalous coherence signals. Finally, the effective coherence signals corresponding to the correct envelope are extracted. Surface topography measurement of the nanopillars on the metasurface is obtained from the extracted signals. These nanopillars are distributed with a varying duty cycle and their diameters range from 590 to 1350 nm, near the lateral resolution limit of 501.9 nm of the system. The topography of nanopillars is recovered from the field of view, while the diameter and height of different types of nanopillars are measured. The mean value and standard deviation of these two parameters are consistent with the results obtained via scanning electron microscopy.

Investigation of Dynamic Responses and Vibration Serviceability of Temporary Grandstands by a 3 DOF Interaction Model due to Swaying Motion

Excessive vibration of temporary grandstand by the crowd has lateral rhythmic motions, which attracted increasing attention in the recent years. This paper focuses on experiments where a temporary grandstand occupied by 20 participants is oscillated by a shaking table with a series of random waves and the crowd-induced rhythmic swaying motions at lateral direction, respectively. The dynamic forces that were induced by participants who have swayed at 0.5–1.8 Hz are recorded by a tri-axial human biomechanics force plate. A new relationship between the annoyance rate and structural acceleration at logarithmic coordinate is investigated and proposed, and the swaying load model is given. Based on these experimental results, a simplified three-degree-of-freedom lumped dynamic model of the joint human–structure system is reinterpreted. Afterwards, combined with a feasible range of crowd/structural dynamic parameters, a series of interaction models are analyzed, the vibration dose value (VDV) of the structure is obtained and discussed, and the notable parameters for interaction model are predicted. The experimental results show that the lateral serviceability limit is 1.29 m/s1.75 and the upper boundary is 2.32 m/s1.75. The dynamic response of model indicated that the VDV of structure will be decreased with increasing the mass of static crowd and damping ratio of the dynamic crowd. The max response of the model is α ≤ 0.6, f2 = 1.8 Hz or α &gt; 0.6, f2 = 1.5 Hz or f1 = 2.5–3.5 Hz. It may be used as a reference value in vibration safety and serviceability assessment of TDGs, to estimate realistically the vibration response on the occasions when the crowds are swaying.