Digital Video System Research Articles

Reducing DC-DC power

High efficiency DC-DC converter designs are vital for high efficiency power consumption. Designers of power supplies for battery driven products face the challenge of selecting the right integrated switched mode converter chips from an ever increasing number of vendors. Each vendor of course claims to offer the best solution for their application. Having selected the right product, the designer then has to make the right tradeoffs between certain design parameters. One of the most critical of these is the system's power consumption. Designing for the highest efficiency is therefore discussed in this article using the TPS6103x boost converter IC family from Texas Instruments as an example in the design of a power supply for a portable digital audio and video system.

Measurement of a velocity field in microvessels using a high resolution PIV technique.

Because endothelial cells are subject to flow shear stress, it is important to determine the velocity distribution in microvessels during studies of the mechanical interactions between the blood and the endothelium. Particle image velocimetry (PIV) is a quantitative method for measuring velocity fields instantaneously in experimental fluid mechanics. The authors have developed a high-resolution PIV technique that improves the dynamic flow range, spatial resolution, and measurement accuracy. The proposed method was applied to images of the arteriole in the rat mesentery, using an intravital microscope and high-speed digital video system. Taking the mesentery motion into account, the PIV technique was improved to measure red blood cell (RBC) velocity. Velocity distributions with spatial resolutions of 0.8 3 0.8 mm were obtained even near the wall in the center plane of the arteriole. The arteriole velocity profile was blunt in the center region of the vessel cross-section and sharp in the near-wall region. Typical flow features for non-Newtonian fluid are shown.

Scapulohumeral rhythm: relationship between motion velocity and rhythm.

The relative contributions of scapulothoracic and glenohumeral motion at different rates of shoulder motion were studied through adduction to abduction in the scapular plane. Nineteen shoulders of 10 healthy individuals (all men, 24-30 years of age) were analyzed using an image intensifier and a high-resolution digital video system. High- and low-speed motion consisted of 2 and 4 seconds per one cycle, respectively, from abduction to adduction in the scapular plane. Glenohumeral and scapulothoracic ratios were fixed at low speed and these results agree with the finding of other researchers. Ratios at high speed were not fixed and differed significantly from those at low speed. Ratios were high at the beginning of abduction or adduction and at angles beyond 40 degrees abduction, then decreased according to the arm movement. Glenohumeral motion at high speed was more dominant at the beginning of abduction or adduction beyond the setting phase, then became less dominant according to the arm movement, compared with the motion at low speed.

In vivo PIV measurement of red blood cell velocity field in microvessels considering mesentery motion

As endothelial cells are subject to flow shear stress, it is important to determine the detailed velocity distribution in microvessels in the study of mechanical interactions between blood and endothelium. Recently, particle image velocimetry (PIV) has been proposed as a quantitative method of measuring velocity fields instantaneously in experimental fluid mechanics. The authors have developed a highly accurate PIV technique with improved dynamic range, spatial resolution and measurement accuracy.In this paper, the proposed method was applied to images of the arteriole in the rat mesentery using an intravital microscope and high-speed digital video system. Taking the mesentery motion into account, the PIV technique was improved to measure red blood cell (RBC) velocity. Velocity distributions with spatial resolutions of 0.8 × 0.8 μm were obtained even near the wall in the centre plane of the arteriole. The arteriole velocity profile was blunt in the centre region of the vessel cross-section and sharp in the near-wall region. Typical flow features for non-Newtonian fluid were shown. Time-averaged velocity profiles in six cross sections with different diameters were compared.

A motion of forearm supination with maintenance of elbow flexion produced by electrical stimulation to two elbow flexors in humans

Motions of the forearm induced by electrical stimulation to two elbow flexors (brachioradialis: BR, biceps brachii: BB) were examined in five healthy human subjects. Stainless steel wire electrodes were implanted percutaneously into each motor point of the muscles. The muscles were stimulated separately with a computer-controlled multi-channel stimulator. The motions were taken with a digital video system. Angular changes of the motions in elbow flexion/extension and forearm pronation/supination were measured. Electromyograms (EMG) of BR, BB, and the triceps brachii (TB) were recorded. Electrical stimulation to BR induced a motion of flexion and that to BB motions of flexion and supination. The stimulation to BR with an adequate intensity provided holding of flexion with the prone forearm in all the subjects. In this situation, additional stimulation to BB resulted in motions of flexion and supination. However, the additional stimulation accompanied with a decrease of the stimulation intensity for BR provided a motion of supination with maintenance of the flexion in all the subjects. Since during the stimulation BR, BB, and TB showed no voluntary contraction in EMG, it is suggested that modulation of contraction between BR and BB by the stimulation can produce force in supination with keeping constant force in flexion to support the weight below the elbow.

Automatic TV advertisement detection from MPEG bitstream

The Centre for Digital Video Processing at Dublin City University conducts concentrated research and development in the area of digital video management. The current stage of development is demonstrated on our Web-based digital video system called Fı́schlár (Proceedings of the Content based Multimedia Information Access, RIAO 2000, Vol. 2, Paris, France, 12–14 April 2000, p. 1390), which provides for efficient recording, analysing, browsing and viewing of digitally captured television programmes. Advertisement breaks during or between television programmes are typically recognised by a series of ‘black’ video frames simultaneously accompanying a depression in audio volume which separate each advertisement from one another by recurrently occurring before and after each individual advertisement. It is the regular prevalence of these flags that enables automatic differentiation between what is programme and what is a commercial break. This paper reports on the progress made in the development of this idea into an advertisement detector system that automatically detects the commercial breaks from the bitstream of digitally captured television broadcasts.

PIV Measurement of Red Blood Cell Velocity Field in Microvessels

As endothelial cells are subject to flow shear stress. it is important to determine the detailed velocity distribution in microvessels in the study of mechanical interactions between blood and endothelium. Recently. particle image velocimetry (PIV) has been proposed as a quantitative method of measuring velocity fields instantaneously in experimental fluid mechanics. The authors have developed. a highly accurate PIV technique with improved dynamic range. spatial resolution and measurement accuracy. In this paper, the proposed method was applied to images of the arteriole in the rat mesentery using an intravital microscope and high-speed digital video system. Taking the mesentery motion into account. the PIV technique was improved to measure red blood cell (RBC) velocity. Velocity distributions with spatial resolutions of 0.8×0.8 μm were obtained even near the wall in the center plane of the arteriole. Ensemble averaged time-series of velocity profiles in cross sections were compared. The arteriole velocity profile was blunt in the center region of the vessel cross-section and sharp in the near-wall region.

Enhancing Athletic Performance Using Digital Video in Consulting

Video has been used successfully in psychosocial interventions to help train communication skills, document behaviors, and as a feedback tool for behavior modification strategies. The need for equipment portability, together with editing expertise, has limited video use in sport psychology. Newer digital video systems help overcome these problems, meaning that sport psychologists can readily use this technology in the field. We discuss and provide experiential observations of how digital video can be used to improve player, coach, and team performance. Also reviewed are new consultation opportunities for sport psychologists with video skills. These new areas center on perceptual skills training and talent identification using perceptual skills testing.

Deformation and strain characteristics along the length of the anterior band of the inferior glenohumeral ligament

Efficacious surgical treatment of anterior glenohumeral instability often requires repair of the anteroinferior capsulolabral structures, including the glenoid origin of the anterior band of the inferior glenohumeral ligament. Rupture in this location, the Bankart lesion, may be accompanied by nonrecoverable stretching of the anterior band. The purpose of this study was to evaluate the amount and location of nonrecoverable stretching with tensile testing. Twelve glenoid-soft tissue-humerus complexes from fresh-frozen glenohumeral joints were studied by means of a custom jig, an Instron machine, and a video digitizing system. The joints were positioned to simulate that known to cause apprehension for anterior instability. Nonrecoverable deformation differed along the length of the anterior band but was slight in all locations. For those that failed at the glenoid insertion region, the mean nonrecoverable deformation was 0.10 ± 0.16 mm (mean ± SEM) at the bone-labral junction of the glenoid insertion region and 0.38 ± 0.23 mm at the labral-ligament junction of the glenoid insertion region. It was 0.53 ± 0.23 mm at the ligament midsubstance and 0.04 ± 0.10 mm at the humeral insertion region. For those that failed at the glenoid insertion region, the nonrecoverable stretching was 1.4% ± 1.9% at the bone-labral junction of the glenoid insertion region and 3.5% ± 2.0% at the labral-ligament junction of the glenoid insertion region. It was 2.3% ± 1.1% at the ligament midsubstance and 0.0% ± 1.4% at the humeral insertion region. Rupture of the anterior band resulted in little nonrecoverable stretching at both the site of failure and elsewhere along the length, remote from the failure site. Surgical repairs after initial dislocation may restore the length of the anterior band of the inferior glenohumeral ligament with little shortening. (J Shoulder Elbow Surg 2001;10:482-8.)

Data semantics for improving retrieval performance of digital news video systems

We propose a novel four-step hybrid approach for retrieval and composition of video newscasts based on information contained in different metadata sets. In the first step, we use conventional retrieval techniques to isolate video segments from the data universe using segment metadata. In the second step, retrieved segments are clustered into potential news items using a dynamic technique sensitive to the information contained in the segments. In the third step, we apply a transitive search technique to increase the recall of the retrieval system. In the final step, we increase recall performance by identifying segments possessing creation-time relationships. A quantitative analysis of the performance of the process on a newscast composition shows an increase in recall by 59 percent over the conventional keyword-based search technique used in the first step.

Development of a Digital Stereoscopic Video System with Embedded High Resolution Images

Development of a Digital Stereoscopic Video System with Embedded High Resolution Images

Blood Flow Velocity Measurement in Microcirculation Field by Means of Highly Accurate Iterative PIV.

Particle image velocimetry (PIV) has been the quantitative measurement method of instantaneous velocity fields in experimental fluid mechanics. The authors have proposed the adaptive PIV technique using the gradient-based sub-pixel analysis, in which a pixel unit displacement is obtained using the iterative cross-correlation method while a sub-pixel displacement is calculated by the use of the so-called spatio-temporal derivative method. The present method can achieve high accuracy of measurement and high spatial resolution compatibly. In this paper, the proposed method is applied to visualized images of the arteriole in the rat mesentery using the intravital-microscope and the high-speed digital video system. Time-series of the volocity profiles of the arteriole is obtained. Averaged velocity profiles show the blood flow volume is constant at five vessel cross-sections. The arteriole velocity profiles are blunt at the center region of the vessel cross-section and sharp profiles at near wall region, this suggests the shear stress on the vessel wall is higher than expected one. The results show that the proposed method is very useful to measure the blood flow velocity profiles with highly accuracy of measurement, and high temporal and spatial resolution.

高精度PIV手法による微小血管内流場の解析

Since endothelial cells are subject to flow shear-stress, it is important to determine the fine velocity distribution in microvessels for studies of mechanical interactions between blood and endothelium. Recently, particle image velocimetry (PIV) is a quantitative method of measuring velocity fields instantaneously in experimental fluid mechanics. The authors have been developed a high-resolution PIV technique, which can improve the dynamic range, spatial resolution and measurement accuracy, and applied it to visualized images in a blood flow.In this paper, the proposed method is applied to visualized images in micro tube using an intravital-microscope and high-speed digital video system in order to assess measurement accuracy. The obtained velocity profile corresponds to a theoretical value. Then the micro PIV system is applied to a blood flow of straight tube in rat mesentery arterioles.

Interaction between L-type Ca2+ channels and sarcoplasmic reticulum in the regulation of vascular tone in isolated rat small arteries.

A dysfunction of the sarcoplasmic reticulum (SR) causes an increase in the myogenic tone of rat skeletal muscle small arteries (A(SK)), but not that of mesenteric small arteries (A(MS)). We hypothesized that the difference depends on the activity of voltage-dependent Ca2+ channels in these vessels. To test this, we measured the membrane potential of these vessels and examined ryanodine-induced constrictions by manipulating the activity of voltage-dependent Ca2+ channels. The isolated vessels were cannulated to control the transmural pressure. To assess the vascular tone, the inner diameter was measured with a video-digitizing system. The membrane potential of A(SK) was more depolarized between 20 to 100 mm Hg of transmural pressure. A(MS) was not constricted by the Ca2+ channel agonist Bay K 8644 (1 nM(-1) microM) alone, but substantially constricted in the presence of ryanodine (1 microM). Ryanodine also augmented the KCl (20 mM)-induced constriction. In A(SK), the Ca2+ channel blocker nisoldipine fully dilated the ryanodine-induced constriction: however, the ryanodine-induced constriction was less susceptible to nisoldipine than was the myogenic and phenylephrine-induced constriction caused mainly by increased Ca2+ influx. In conclusion, the contribution of the SR function to Ca2+ metabolism depends on the activity of dihydropyridine-sensitive Ca2+ channels. The dysfunction of SR by ryanodine may impair the Ca2+ extrusion rather than increase Ca2+ influx in rat small arteries.

Kinetics of constant gravitropic stimulus responses in Arabidopsis roots using a feedback system.

The study of gravitropism is hindered by the fact that as a root responds, the gravitational stimulus changes. Using a feedback system to connect a rotating stage platform to a video digitizer system, we were able to maintain a constant angle of gravistimulation to Arabidopsis roots for long time periods. The rate of curvature approximated the sine rule for angles of stimulation between 20 degrees and 120 degrees. For a given angle of stimulation, the rate of curvature also remained constant, with no observed diminishment of the response. Although previous reports of Arabidopsis root gravitropism suggest latent periods of approximately 30 min, using a smooth mechanical stage to reorient the root, we observed a mean time lag of approximately 10 min. This more rapid onset of curvature can, in part, be explained by reduced mechanical perturbation during the process of gravistimulation. This suggests that mechanical stimulation associated with rapid root re-orientation may confound investigations of early gravitropic events.

A111高解像度PIV手法を用いた微小血管内の速度分布計測

Particle image velocimetry (PIV) is a quantitative method of measuring velocity fields instantaneously in experimental fluid mechanics. In order to improve the dynamic range, resolution and accuracy, the authors has proposed a new high-resolution PIV technique based on iterative cross-correlation and gradient method. The proposed method has the error of the order of 0.01 pixels.In this paper, the proposed method is applied to visualized images of the arteriole in the rat mesentery using the intravital-microscope and the high-speed digital video system. Time-series of the velocity profiles of the arteriole was obtained. Averaged velocity profiles shows the blood flow volume were constant at five vessel cross-sections. The arteriole velocity profile was blunt at center region of the vessel cross-section and sharp profiles at near wall region, this suggests the shear stress on the vessel wall is higher than expected. The results show that the proposed method is very useful to measure the blood flow velocity profiles with high accurate, temporal and spatial resolution.

Digital Film Mastering

A new approach for generating video masters from film originals is presented in this paper. The basis is a high-throughput film scanner with a data output option that enables the generation of a high-resolution digital data copy. By combining standard computer platforms and dedicated processing hardware, an integrated system is created where multiple master video copies of differing formats can be derived from a single digital data copy. This flexible and efficient method of generating different versions of a program facilitates multimedia distribution of an original film. The paper also presents the overall concept and architecture for digital film mastering and explains, in particular, the architecture of a crucial component: the post-processing unit. The specific challenges that arise from the processing of continuous data streams at rates up to 420 Mbytes/sec are discussed. An example based on an actual film scanner from Philips Digital Video Systems is used to illustrate the method.

Issues in vision modeling for perceptual video quality assessment

Lossy compression algorithms used in digital video systems produce artifacts whose visibility strongly depends on the actual image content. Simple error measures such as RMSE or PSNR, albeit popular, ignore this important fact and are only a mediocre predictor of perceived quality. Many applications require more reliable assessment methods. This paper discusses issues in vision modeling for perceptual video quality assessment (PVQA). Its purpose is not to describe a particular model or system, but rather to summarize and to provide pointers to up-to-date knowledge of important characteristics of the human visual system, to explain how these characteristics may be incorporated in vision models for PVQA, to give a brief overview of the state-of-the-art and current efforts in this field, and to outline directions for future research.

Age related biomechanical properties of the glenoid–anterior band of the inferior glenohumeral ligament–humerus complex

Objective. To quantify the biomechanical properties of the glenoid–anterior band of the inferior glenohumeral ligament–humerus complex for the two age groups. Design. In vitro human cadaver study evaluating the biomechanical properties of the glenoid–anterior band of the inferior glenohumeral ligament–humerus complex for a younger group ( n=5, mean age 38.5, SD 0.5 years) and an older group ( n=7, mean age 74.8, SD 5.3 years). Background. Glenohumeral instability is more of a problem in younger than in older individuals, primarily because recurrence is much more common at a young age. Methods. Tensile testing was performed on the glenoid–anterior band of the inferior glenohumeral ligament–humerus complex in the shoulder apprehension position using a custom jig, Instron machine and a video digitizing system. Results. In the younger individuals disruption of the complex most often occurred at the glenoid–labrum region of the glenoid insertion site. In the older individual, disruption most often occurred at the midsubstance region. The load and the stress at failure of the glenoid–anterior band of the inferior glenohumeral ligament–humerus complex showed that the older group was only 61% and 46% of the younger group, respectively. Conclusions. The structural properties of the glenoid–anterior band of the inferior glenohumeral ligament–humerus complex and the material characteristics of the anterior band of the inferior glenohumeral ligament for the younger group were significantly superior than the older group. Relevance A stronger and more extensive repair, such as the traditional open technique, may be necessary for younger individuals with glenohumeral instability whereas in older individuals, a different repair technique, such as an arthroscopic technique, may be sufficient.

Effects of screw types in cementless fixation of tibial tray implants: stability and strength assessment

Objective. To test the stability and strength of tibial trays fixed with cortical screws and tibial trays fixed with cancellous screws under axial and anterior–posterior shear loading conditions. Design. Five matched human fresh frozen cadaver knees without prior pathology were used as paired specimens for comparison of cortical to cancellous screw fixation of tibial trays. Background. Current cementless fixation of tibial trays in total knee arthroplasty is obtained by using a combination of stems, keels, posts, pegs, and screws. To date there has been no study comparing isolated cortical and cancellous screw fixation in cementless arthroplasty. Methods. An Instron machine and a video digitizing system were used to examine tibial tray lift-off, subsidence, and anterior–posterior load to failure at the bone–implant interface in five matched pairs of knees and compare the difference between cancellous and cortical screw fixation. Results. Non-destructive cyclic testing showed a significant difference between the two types of screws for tibial tray subsidence with cancellous fixation greater than cortical ( P < 0.05), but not for lift-off ( P > 0.05). Load to failure testing in anterior–posterior direction did not result in a significant difference between the two types of screws for initial stiffness and ultimate load ( P > 0.05), but did result in a significant difference of energy absorbed to failure ( P < 0.01). Conclusions. The difference in amount of subsidence between cortical and cancellous fixation could possibly be due to microfractures of the underlying trabecular bone with cancellous fixation. Neither screw type was able to completely fix the tibial tray to bone and prevent micromotion. Although the load at failure for anterior–posterior shear was similar for the two screw types, the energy absorbed was greater for the cortical screws which may be a result of additional strength provided by the cortical bone surrounding the screw. Relevance The results from this study indicate that cortical screws may provide a more stable initial fixation for tibial trays when compared to cancellous screws in total knee arthroplasty.