Plane Distance Research Articles

Measuring the principal planes and effective focal length of an optical imaging system

We present a simple method to measure the two principal planes and the effective focal length of an imaging optical system. It is based on measurements of transverse magnification of the image and both the object and image positions from two arbitrary reference points. A simple linear equation is derived to find the distances of the principal planes from the reference points, which enables the computation of the effective focal length. Experimentally, the method only needs a standard optical bench, thus avoiding the use of a nodal slide. The accuracy obtained for a practical example with an optical system composed of two achromatic doublets is smaller than 1 mm, or better than 2%, for all three measured values (two principal planes and the one effective focal length) as compared with the results of optical ray tracing performed with OSLO software.

Didactic laser speckle experiments with a lensless camera

Laser speckles are granular patterns created through the interference of coherent light scattered by a rough surface. Besides comprising an appealing optical phenomenon, the speckle patterns enable applications in physical and biochemical measurements. This paper proposes didactic far-field (objective) speckle experiments using a visible laser source and a lensless webcam for implementation in optics labs or at home. Firstly, a ceramic mug works as the scattering surface to investigate the effect of the target-observation plane distance on the average size of light granules. Secondly, the speckle pattern deviations produced by the liquid inside the recipient are analysed to measure mass and temperature changes. Finally, the mug is replaced with a leaf to evaluate its biological activity based on the scattered light. Image processing tools carry out the quantification of speckle parameters like average size and correlation coefficient, achieving a good agreement between theory and practical results. The proposed far-field speckle experiments explore topics related to optics, instrumentation, and image computing straightforwardly, developing the desired skills for undergraduate and graduate students of physics and engineering courses.

Synergistic Interface and Mesopore Engineering with More and Quicker Ion Storage for Enhanced Performance of Lithium‐Ion Battery

AbstractDesigning hetero‐nanostructures is widely recognized as an effective modification strategy to obtain ZnO/Co3O4 anode materials with superior electrochemical properties. However, the lithium‐ion storage behavior of ZnO/Co3O4 has not reached a satisfied performance. Herein, based on our previous DFT results that the interface of ZnO(110)/Co3O4(220) hetero‐nanostructure possesses fast reaction kinetics because of more negative surface adsorption energy and lower diffusion barrier energy of lithium ions, we developed ZnO(110)/Co3O4(220)@C hetero‐nanostructures with both abundant interfaces and uniform mesopores structure derived from 2D MOF precursor. Especially, ZnO/Co3O4@C hybrid materials with ZnO(110)/Co3O4(220) hetero‐nanostructure show strong electronic interactions and the widen distance of the crystal plane at the interface, resulting in stable hetero‐nanostructures with faster ion diffusion channel and more active sites. Moreover, this material possesses uniform mesopores and 2D structure, which enables quicker transport capability and cycling longevity for lithium‐ion storage. Impressively, when ZnO/Co3O4@C was used as anodes in lithium‐ion batteries, the electrodes deliver improved initial specific capacities (1,630.5 and 1,496.9 mAh g−1 at 0.2 and 0.5 A g−1), excellent capacity retention (1,758.3 mAh g−1 after 370 cycles at 0.2 A g−1, and 607.7 mAh g−1 up to 650 cycles at 5 A g−1), and superior rate capacity (937 and 468 mAh g−1 at 1.0 and 5.0 A g−1 after 360 cycles).

Fast and Accurate Normal Estimation for Point Clouds Via Patch Stitching

This paper presents an effective normal estimation method adopting multi-patch stitching for an unstructured point cloud. The majority of learning-based approaches encode a local patch around each point of a whole model and estimate the normals in a point-by-point manner. In contrast, we suggest a more efficient pipeline, in which we introduce a patch-level normal estimation architecture to process a series of overlapping patches. Additionally, a multi-normal selection method based on weights, dubbed as multi-patch stitching, integrates the normals from the overlapping patches. To reduce the adverse effects of sharp corners or noise in a patch, we introduce an adaptive local feature aggregation layer to focus on an anisotropic neighborhood. We then utilize a multi-branch planar experts module to break the mutual influence between underlying piecewise surfaces in a patch. At the stitching stage, we use the learned weights of multi-branch planar experts and distance weights between points to select the best normal from the overlapping parts. Furthermore, we put forward constructing a sparse matrix representation to reduce large-scale retrieval overheads for the loop iterations dramatically. Extensive experiments demonstrate that our method achieves SOTA results with the advantage of lower computational costs and higher robustness to noise over most existed approaches.

Comparison of augmented reality and cutting guide technology in assisted harvesting of iliac crest grafts – A cadaver study

BackgroundHarvesting vascularized bone grafts with computer-assisted surgery represents the gold standard for mandibular reconstruction. However, current augmented reality (AR) approaches are limited to invasive marker fixation. This trial compared a markerless AR-guided real-time navigation with virtually planned and 3D printed cutting guides for harvesting iliac crest grafts. Material and methodsTwo commonly used iliac crest transplant configurations were virtually planned on 10 cadaver hips. Transplant harvest was performed with AR guidance and cutting guide technology. The harvested transplants were digitalized using cone beam CT. Deviations of angulation, distance and volume between the executed and planned osteotomies were measured. ResultsBoth AR and cutting guides accurately rendered the virtually planned transplant volume. However, the cumulative osteotomy plane angulation differed significantly (p = 0.018) between AR (14.99 ± 11.69°) and the cutting guides (8.49 ± 5.42°). The cumulative osteotomy plane distance showed that AR-guided navigation had lower accuracy (2.65 ± 3.32 mm) than the cutting guides (1.47 ± 1.36 mm), although without significant difference. ConclusionThis study demonstrated the clinical usability of markerless AR-guided navigation for harvesting iliac crest grafts. Further improvement of accuracy rates might bring clinical implementation closer to reality.

V06-01 WHAT TO DO WHEN UNABLE TO REACH THE BLADDER DURING HOLMIUM LASER ENUNCLEATION OF THE PROSTATE (HOLEP): AN INCISION-FREE APPROACH

You have accessJournal of UrologyBPH & Infection & Imaging (V06)1 Sep 2021V06-01 WHAT TO DO WHEN UNABLE TO REACH THE BLADDER DURING HOLMIUM LASER ENUNCLEATION OF THE PROSTATE (HOLEP): AN INCISION-FREE APPROACH Deepak Agarwal, and Marcelino Rivera Deepak AgarwalDeepak Agarwal More articles by this author , and Marcelino RiveraMarcelino Rivera More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000002021.01AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: The situation of not being able to reach the bladder during HoLEP is a rare situation. Currently, this situation requires some external incision (temporary perineal urethrostomy (PU) or conversion to open/MIS simple prostatectomy) which requires additional catheterization time. We present an alternative, incision-free technique for this situation to complete HoLEP transurethrally. METHODS: We present a case of HoLEP in a 73 year old male with a 225 ml gland on preoperative imaging in which the laser scope could not reach the bladder due to urethral length. We utilized the early apical release technique, and dissected to the bladder through the anterior plane. As this is the shortest distance across the prostate to the bladder endoscopically, we were able to reach the bladder anteriorly and complete the HoLEP without additional incisions. This also enabled us to perform catheter removal promptly after surgery. RESULTS: The total procedure time was 146 minutes, enucleation time was 97 minutes and morcellation time was 24 minutes. All of the 199 grams of enucleated tissue was benign adenoma on final pathology. In the 15 minutes between procedure end time and extubation, continuous bladder irrigation was run through a 22 french three-way urinary catheter. The catheter was removed prior to extubation and the patient voided within 2 hours. At two week follow-up, the patient was voiding without issue, having only minimal stress urinary incontinence, and no hematuria. CONCLUSIONS: We propose the technique of first following anterior plane to the bladder after early apical release as an when the laser scope cannot reach the bladder transurethrally at the time of HoLEP. The shorter distance of the anterior plane from the apex of the prostate to the bladder neck, opposed the longer distance through the urethral lumen is the likely reason for the success of this approach. This anterior-first technique may avoid external incisions and prolonged catheter time from a temporary PU or open/MIS prostate enucleation in these rare cases. Source of Funding: N/A © 2021 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 206Issue Supplement 3September 2021Page: e449-e449 Advertisement Copyright & Permissions© 2021 by American Urological Association Education and Research, Inc.MetricsAuthor Information Deepak Agarwal More articles by this author Marcelino Rivera More articles by this author Expand All Advertisement Loading ...

One-step Bridging of g-C3N4 and Graphene Oxide by Successive Electrolysis for Constructing Electrochemical Sensor of Pb2+

Synthesis methods of composites materials can tailor individual materials properties and make the composite possess more superior performance than individual materials. Herein, by combining –NH 2 group in graphitic carbon nitride (g-C 3 N 4 ) and a facile electrolytic route, g-C 3 N 4 -bridging reduced graphene oxide nanocomposite (g-C 3 N 4 /r-GO) was successfully prepared to construct chemical sensor for detection of Pb 2+ . Because g-C 3 N 4 contains a large amount of –NH 2 group, covalent bonds as bridges between GO and g-C 3 N 4 could be successfully formed by successively electrolyzing, which simultaneously induced removal of electron withdrawing group in r-GO. Such bridges could shorten the planar distance between GO and g-C 3 N 4 in comparison with the conventional π-π stacking, improving the electrochemical performance of r-GO and g-C 3 N 4 . Moreover, the above unique chemical structure of g-C 3 N 4 /r-GO not only exhibited excellent electrical conductivity but also provided plenty active sites to chelate Pb 2+ from solution. Therefore, the prepared g-C 3 N 4 /r-GO ensured chemical sensor for Pb 2+ detection with wide linear range (1.0–300 μg/L) and low detection limit (0.15 μg/L at S / N = 3). This simple method could also be extended to preparation of other elements-contained nanomaterials functionalized oxide graphene for improve its properties and widen its potential applications. Covalent bonds as bridges between GO and g-C 3 N 4 was successfully formed by successively electrolyzing which simultaneously induce removal of electron withdrawing group in GO. Such bridges can shorten the planar distance between r-GO and g-C 3 N 4 in comparison with the conventional π-π stacking, improving the electrochemical performance of the r-GO and g-C 3 N 4 . The prepared g-C 3 N 4 /r-GO not only exhibited excellent the electrical conductivity but also provided plenty active sites to chelate Pb 2+ from solution.

Vapour–liquid–liquid and vapour–liquid equilibrium of paraffinic aromatic synthetic naphtha/water blends: Prediction of the number of phases

AbstractBitumen is extracted from oil sands using warm water and additives. The resulting bitumen froth is diluted with naphtha in a froth treatment process. Residual naphtha in the aqueous tailings of the froth treatment unit is recovered in a naphtha recovery unit (NRU). It is imperative to maximize the naphtha recovery process to minimize the plant's environmental and economic impact. It is, in this respect, that NRU vapour–liquid–liquid equilibrium data is of significant value. In this work, a paraffinic‐aromatic synthetic naphtha (PASN) with a true boiling point (TBP) similar to that of froth treatment naphtha is used. Water/PASN mixtures are studied using the Soave‐Redlich‐Kwong equation of state with a Kabadi‐Danner modification. The tangent plane distance (TPD) is evaluated as a possible criterion to calculate the number of phases, with its significant shortcomings being established. As well, experimental data obtained in a CREC‐VL‐Cell is observed to display higher solubilities of PASN in water than the ones obtained by HYSYS‐Aspen Plus V9 simulation. To address these issues, a machine learning (ML)‐based phase classification methodology was considered, predicting the number of phases with a 99% recall. This anticipates that ML will be of significant value for faster convergence of the flash split calculations for the naphtha hydrocarbon‐water systems under consideration.

A reconsideration on the resolution of phase stability analysis using stochastic global optimization methods: Proposal of a reliable set of benchmark problems

Phase stability analysis is an important thermodynamic calculation in the context of process systems engineering of multiphase units (e.g., separation systems, reactors). It implies the minimization of the Tangent plane distance function (TPDF), which has been recognized as a challenging global optimization problem. Despite the importance of this thermodynamic calculation, the characterization and classification of resolution complexity of phase stability problems that are commonly used to test and compare global optimization methods have not been addressed in literature. This paper reports the first step to propose a set of benchmark TPDF problems to assess and identify the advantages and limitations of stochastic optimization methods used in phase stability calculations. A detailed review of TPDF problem reported in literature was performed and the most representative ones were studied and classified in terms of their resolution complexity via the analysis of several performance metrics associated to both reliability and efficiency to find the global TPDF minimum. Differential Evolution, Simulated Annealing, Harmony Search, Tabu Search, Particle Swarm Optimization and Genetic Algorithm were selected as the metaheuristics to perform the global minimization of selected TPDF problems. 35 phase stability problems were classified in low, medium and high difficulty TPDF problems. Results showed that, although a wide variety of phase stability problems has been reported and used for phase stability calculations, a significant number of them corresponded to global optimization problems of easy resolution. Therefore, some authors have reported biased conclusions on the performance of stochastic optimization methods. A set of 23 TPDF was proposed as benchmark problems to obtain a reliable analysis of the numerical performance of metaheuristics employed in phase stability calculations. This benchmark set contains problems with different resolution difficulties and characteristics that are considered appropriate to study and assess new methods to resolve the global TPDF optimization, as well as to improve the existing methods. This paper highlights the relevance of a continuous development and improvement of stochastic global optimizers for solving, robustly and efficiently, the phase stability analysis in multicomponent systems. TPDF minimization can be still considered a challenging problem to be faced in the context of applied thermodynamics.

Percutaneous Coronary Sinus-Based Mitral Valve Repair Differentially Modulates Coronary Sinus to Mitral Valve Annulus Geometry and Topography

Objectives: Coronary sinus (CS) based mitral annuloplasty using the Carillon device is a therapeutic option for the treatment of functional mitral valve regurgitation (FMR).Background: Little is known about the change of CS and mitral valve annulus (MVA) planes following Carillon implantation and how they are modulated by the tension applied on the device.Methods: In a retrospective single-center analysis, 10 patients underwent Carillon device implantation and received CT-angiography (CTA) prior and post CS based percutaneous mitral valve repair. Patients were assigned to responders or non-responders according to the 3-month transthoracic echocardiographic follow-up. A prototype software was used to assess distance and angulation of both CS (pre) or Carillon-device (post) and mitral annulus planes.Results: Comparison of the distance and angulation of the CS plane or Carillon device plane and the MVA plane prior and post intervention showed significant reduction of distance and unchanged angulation in responders while angulation was increased and distance reduced in non-responders without statistical significance. Furthermore, in FMR responders MVA perimeter, anterior-posterior diameter, intercommisural diameter and MVA area were decreased following successful indirect mitral valve annuloplasty, while in FMR non-responders Carillon device implantation had no effect on MVA geometry.Conclusions: Insufficient reduction of FMR following indirect mitral valve annuloplasty is associated with device malposition in relation to the mitral valve annulus. Patient selection using CTA-derived distance and angulation of CS to MVA planes is one option to increase effectiveness of indirect mitral valve annuloplasty.

Multi-layered thin film nanocomposite MoS2@MoO2/MWCNP/ITO-PET: Electrochemical approaches for synthesis and structural characterizations

A shell@core nanostructure of MoS2@MoO2 on multi-walled carbon nanotubes paper (MWCNP) is fabricated by a two-step electrochemical process. Consecutively, electrophoretic deposition (EPD) and galvanostatic deposition (GSD) techniques are applied to deposit MWCNP on indium tin oxide coated polyethylene terephthalate (ITO-PET) film, then, to form MoS2@MoO2 on the surface of MWCNP. Raman spectra and XRD pattern of MWCNP/ITO-PET and MoS2@MoO2/MWCNP/ITO-PET thin films confirm EPD retains the original structure of MWCNTs as well as GSD successfully generates amorphous MoS2@MoO2 as skin of MWCNP. In EPD process, MWCNT-COOH with high defect density are preferred to deposition on ITO-PET electrode as well as MoS2@MoO2 reduces defect on sidewall of MWCNTs in GSD process. The XRD patterns confirms the orthorhombic and hexagonal structure of MoO2 and MoS2, respectively. The thickness of MoS2@MoO2 skin measured on TEM images is about 13–15 nm, while the planes distance measured on HRTEM is about 3.8 Å. Combination of characterization shows the mechanism leading to formation of MoS2@MoO2 nano-trail and nano-onion on body and end of MWCNTs, respectively, according defect density of the position. Thence, the two-step electrodeposition holds great potential due to its ability to rapidly produce large-area thin films as well as control nanostructures of materials.

Bisindole [3]arenes—Indolyl Macrocyclic Arenes Having Significant Iodine Capture Capacity

Bisindole [3]arenes—Indolyl Macrocyclic Arenes Having Significant Iodine Capture Capacity

On the correlation between aerodynamic drag and wake flow for a generic high-speed train

The current research attempts to describe the association between the aerodynamic drag and flow structures induced by train running in time-averaged and time-dependant views. A ICE2 train model is used as the research object, with the flow field solved by Large Eddy Simulation (LES). The validation is carried out through comparison with existing research data, and grid independence study in terms of time-averaged and second-order statistics. Numerical results are firstly presented by description of the time-averaged near wake flow topology based on surface flow visualization. Then, the wake integration method is used both time-averaged and instantaneously to link the aerodynamic force with integrated flow quantities on different wake planes: from the time-averaged perspective, the contribution of different flow terms to total drag is presented and compared; from the instantaneous perspective, the overall wake variation tendency is linked to the fluctuating component of aerodynamic force, based on the wake convection velocity and downstream distance of wake planes. The dynamic features of flow quantities in different locations are presented, with cross-correlation method used to describe the correlation between fluctuating aerodynamic drag and wake motion. Approaches and findings presented in the current study could serve as fundamentals which support future study.

Retropharyngeal internal carotid artery: a potential risk factor during nasotracheal intubation.

To investigate the potential risk of the retropharyngeal internal carotid artery (RICA) during nasotracheal intubation (NTI). We retrospectively surveyed 2028patients and 90 healthy controls (HC) with neck computed tomography angiography (CTA). The incidence of RICA was analyzed, as well as the correlation between the average minimum carotid-pharyngeal distance (CPD) and the carotid-median plane distance (CMD). We also compared CPD between RICA and HC. RICA was observed in 91 out of the 2028 patients, reaching an incidence of 4.5% (91/2028). RICA in female patients was 65.9% (60/91) compared to 34.1% (31/91) in male patients. The incidence of RICA at nasopharynx (NP), oropharynx (OP), and hypopharynx (HP) was 31.9% (29/91), 61.5% (56/91), and 6.6% (6/91), respectively. The incidence of the mucosal eminence of the posterior wall of the pharynx in RICA was30.8% (28/91). In 15 cases, RICA caused the pharyngeal cavity to become narrow, with an incidence of 16.5% (15/91). Moreover, CPD and CMD was positively correlated (r = 0.56, p < 0.01). The average minimum CPD of RICA was only 2.25 ± 1.26mm, which was much shorter than HC (17.62 ± 1.98mm) (t = 62.46, p < 0.01). Some CPD of RICA was even less than 1mm, with an incidence of 20.9% (19/91). RICA is not uncommon in asymptomatic adults. It is very close to the midline and posterior wall of the pharynx and is more likely to occur in the nasopharynx (NP) and oropharynx (OP). RICA tear is likely to occur during NTI.

Distinct distances in the complex plane

We prove that if P P is a set of n n points in C 2 \mathbb {C}^2 , then either the points in P P determine Ω ( n 1 − ε ) \Omega (n^{1-\varepsilon }) complex distances, or P P is contained in a line with slope ± i \pm i . If the latter occurs then each pair of points in P P have complex distance 0.

DISCRETE DISLOCATION DYNAMICS SIMULATIONS FOR COMPRESSION OF PARTICLE REINFORCED COMPOSITES

Particle reinforced copper matrix composites have high strength, elastic modulus, excellent electrical and thermal conductivity and wear resistance, they are widely used in aerospace, rail transit, equipment manufacturing and other fields. In particle reinforced composites, the dislocation movement is prevented by small dispersed particles in the alloy, thus effectively improving the mechanical properties of metallic materials and enhancing their service safety. In this paper, the three-dimensional discrete dislocation dynamics (3D-DDD) method was used to simulate the compression of particles reinforced copper matrix composites micro-pillar. The influence of the dislocation-precipitate interaction on the mechanical response of the material was analyzed to reveal the microscopic mechanism of the precipitation strengthening. In this study, the precipitate was regarded as a spherical particle with an impenetrable surface. The dislocation bypass mechanism was used to simulate the interaction between the precipitates and the dislocations. By changing the relative distance of dislocation slip plane against the center of spherical particle, it is found that when the distance is zero, the yield strength and the subsequent strain hardening rate are the highest. As the slip plane is far away from the center of spherical particle, the yield strength and the strain hardening rate decreases. The study also found that the higher the Schmid factor, the lower the yield strength and the lower strain hardening rate. In the simulation of multiple dislocations, it was found that the reaction of dislocations in same slip planes and the interaction of dislocations in different slip systems may be responsible for the reduction of the yield strength and the strain hardening rate.

A facile decoration of anatase Fe3O4/TiO2 nanocomposite with graphene quantum dots: Synthesis, characterization, and photocatalytic activity

A combination of electron-rich graphene quantum dots (GQDs) with Fe3O4/TiO2 nanocomposites may develop an efficient electron transfer for enhanced photocatalytic activity. In this report, a facile decoration of GQDs with maltose precursor was synthesized and loaded onto magnetic anatase TiO2 nanocomposites under hydrothermal methods. The as-synthetized magnetic TiO2/GQDs nanocomposite resulted in a specific surface area of 38.00 m2/g and a total pore volume of 0.186 cm3/g. The HRTEM images showed a lattice plane distance of 0.350 nm related to the interplanar spacing of the anatase TiO2 (101) plane and that of 0.299 nm observed for the in-plane lattice part of GQDs. The effects of magnetic loading ratio and GQDs loading onto TiO2, pH, photocatalyst dosage, and methylene blue (MB) concentration were thoroughly evaluated to find the optimum conditions of mineralization MB for getting the highest photocatalytic efficiency. The removal efficiency of around 86.08 ± 3.62% was obtained at pH11, photocatalytic dose 400 mg/100 mL, and MB concentration 10 mg/L. Moreover, the photogenerated electron transfers and MB degradation mechanism by the resulting Fe3O4/TiO2/GQDS under irradiation of UVA light are proposed. The as-synthesized material improved meaningfully greater photocatalytic efficiency for degrading MB under UVA light irradiation than merely pure anatase TiO2. Also, the predominant mechanism of MB degradation was direct oxidative decomposition through the photogenerated holes. The photocatalytic destruction of MB complied with the apparent first-order models under UVA light irradiation.

Thermodynamic assessment of Mg−Ni−Y system focusing on long-period stacking ordered phases in the Mg-rich corner

• The phase equilibria around LPSOs in Mg-Ni-Y system are experimentally determined. • The thermodynamic stability of LPSOs is discussed based on DFT calculations. • A distort 12R structure is observed through SEAD and HRTEM. • The phase diagram of Mg-Ni-Y system is optimized considering the new 12R LPSO. The long-period stacking ordered phases (LPSOs) in Mg−Ni−Y system have been attracting great interest as effective strengthening components because of their unique structural characteristics and deformation mechanism. However, the phase relationships in LPSOs are complicated and unclear, which restricts the design of advanced magnesium-based alloys. The aim of the present work is to experimentally determine the phase equilibria relationships focusing on LPSOs and establish the thermodynamic description for Mg−Ni−Y system. Four types of LPSOs, that is, 14H, 12R, 18R and 10H, are confirmed through equilibrated alloys and high-resolution transmission electron microscopy (HR-TEM). The formation enthalpies of LPSOs (14H, 12R, 18R and 10H) are calculated based on density functional theories (DFT) calculations. A new ternary compound, termed as τ phase, is observed for the first time which is likely to be the distorted structure of 12R as determined from the TEM image which shows a 12-layer closed packing plane distance of 3.252 nm and a shear angle of 83.2° between (0002) and (10 1 ¯ 0) planes. Based on the determined phase equilibria relationship, the Mg−Ni−Y system is assessed and a self-consistent description is obtained where the LPSOs are modeled as the stoichiometric compounds. The comparison between the calculation result and experimental data suggests the accuracy of the present thermodynamic database in the Mg-rich corner.

Depth perception in single rgb camera system using lens aperture and object size: a geometrical approach for depth estimation

In recent years, with increase in concern about public safety and security, human movements or action sequences are highly valued when dealing with suspicious and criminal activities. In order to estimate the position and orientation related to human movements, depth information is needed. This is obtained by fusing data obtained from multiple cameras at different viewpoints. In practice, whenever occlusion occurs in a surveillance environment, there may be a pixel-to-pixel correspondence between two images captured from two cameras and, as a result, depth information may not be accurate. Moreover use of more than one camera exclusively adds burden to the surveillance infrastructure. In this study, we present a mathematical model for acquiring object depth information using single camera by capturing the in focused portion of an object from a single image. When camera is in-focus, with the reference to camera lens center, for a fixed focal length for each aperture setting, the object distance is varied. For each aperture reading, for the corresponding distance, the object distance (or depth) is estimated by relating the three parameters namely lens aperture radius, object distance and object size in image plane. The results show that the distance computed from the relationship approximates actual with a standard error estimate of 2.39 to 2.54, when tested on Nikon and Cannon versions with an accuracy of 98.1% at 95% confidence level.

Synthesis and Characterization of Mixed-Halide Inorganic-Organic Hybrid CH3NH3PbBr2.5Cl0.5 Perovskite for Photodetector Application

Inorganic-organic hybrid perovskite (ABX3, A = organic cation, B = metal ion, X = halogen anion) combines the advantages of inorganic and organic materials. However, the properties and performance of mixed-halide CH3NH3PbBr2.5Cl0.5 (MAPbBr2.5Cl0.5) are still poorly understood. In this study, we synthetized MAPbBr2.5Cl0.5 single crystal and studied its structure, optical, thermal stability properties and optoelectronics applications for photodetector device. Compared with those of MAPbCl3, the interplanar distance of (100) crystal plane for MAPbBr2.5Cl0.5 becomes larger and the absorption spectrum of MAPbBr2.5Cl0.5 is extended to the visible region. The band gap of the MAPbBr2.5Cl0.5 single crystal is 2.28 eV. We find the device based on MAPbBr2.5Cl0.5 has high selectivity from 369 to 564 nm. The maximum ▴J (Jon– Joff) under 3.0 V bias voltage is about 1.2 µAcmr-2 at 454 nm visible light with 1 W mr-2 light intensity (1/1000 of the standard sunlight intensity), which proves the device has a high sensitivity. The linear relationship is established between the value of ▴J and light intensity and bias voltage. The fast current intensity transients (Fit) shows that the disappearance period of photocurrent density is 0.3 ms, which indicates the device is rapidly responsive photodetector. The highest value (1.7%) of external quantum efficiency (EQE) and the highest value of detectivities (D) both appear at 480 nm visible light at 4.0 V bias voltage when the irradiation power is 30 W m-2. Therefore, this simple and low-cost photoresponsive device is promising for industrial production of photodetector and photocatalysts device in the future.