Versions Of Objects Research Articles

트랜스코딩 프록시에서 세그먼트 기반 캐쉬 교체 정책

최근 스트리밍 미디어는 인터넷 상의 많은 트래픽을 유발하고 있다. 기존의 웹을 위한 객체와 마찬가지로 스트리밍 객체 또한 프록시 시스템을 사용하게 되면 여러 이점이 있긴 하지만, 스트리밍 미디어를 캐슁 하는 방법은 기존의 웹을 위한 객체보다 매우 크고 높은 대역폭을 요구하기 때문에 고려해야 할 점이 많다. 또한 많은 종류의 단말들의 다양한 대역폭을 적절히 서비스 하기 위해서 프록시 기능과 트랜스코딩 기능을 함께 할 수 있는 트랜스코딩 프록시가 유용하다. 기존의 프록시는 객체가 프록시 서버에 저장되어 있거나, 그렇지 않은 경우로만 고려되었으나, 트랜스코딩 프록시에서는 같은 객체의 다양한 버전에 대해서 종합적인 효과를 고려하여 최적의 버전 집합을 저장 해야 한다. 또한 최근의 멀티미디어 캐슁 시스템들은 접근 빈도가 높은 앞부분을 캐슁하여 지연 시간을 줄이고 높은 효율을 얻을 수 있도록 하는 방법을 사용한다. 한편 많은 연구에서 멀티미디어 데이터의 효율적인 저장 관리를 위해서 객체를 세그먼트로 나누어 관리하는 방법을 사용하고 있다. 본 논문에서는 부분 캐슁을 사용하는 트랜스코딩 프록시에서 사용자 요청에 따른 후속 작업을 결정하기 위해 4개의 기본 이벤트를 이용하여 9개의 이벤트로 정의한다. 또한 트랜스코딩 프록시 시스템을 위하여 세그먼트 기반의 관리정책을 제안한다. 실험결과는 제안하는 방법이 사용자 지연시간, BHR와 트랜스코딩 데이터의 양이 적음을 보여준다. Streaming media has contributed to a significant amount of today's Internet Traffic. Like traditional web objects, rich media objects can benefit from proxy caching, but caching streaming media is more of challenging than caching simple web objects, because the streaming media have features such as huge size and high bandwidth. And to support various bandwidth requirements for the heterogeneous ubiquitous devices, a transcoding proxy is usually necessary to provide not only adapting multimedia streams to the client by transcoding, but also caching them for later use. The traditional proxy considers only a single version of the objects, whether they are to be cached or not. However the transcoding proxy has to evaluate the aggregate effect from caching multiple versions of the same object to determine an optimal set of cache objects. And recent researches about multimedia caching frequently store initial parts of videos on the proxy to reduce playback latency and archive better performance. Also lots of researches manage the contents with segments for efficient storage management. In this paper, we define the 9-events of transcoding proxy using 4-atomic events. According to these events, the transcoding proxy can define the next actions. Then, we also propose the segment-based caching policy for the transcoding proxy system. The performance results show that the proposing policy have a low delayed start time, high byte-hit ratio and less transcoding data.

In Defense of the Objective Epistemic Approach to Argumentation

In this paper we defend a particular version of the epistemic approach to argumentation. We advance some general considerations in favor of the approach and then examine the ways in which different versions of it play out with respect to the theory of fallacies, which we see as central to an understanding of argumentation. Epistemic theories divide into objective and subjective versions. We argue in favor of the objective version, showing that it provides a better account than its subjectivist rival of the central fallacy of begging the question. We suggest that the strengths of the objective epistemic theory of fallacies provide support for the epistemic approach to argumentation more generally.

Lightbulbs and nappies: sustainable development and customer perceptions

Recent interest in 'green' versions of everyday objects has led to a market presence for energy-efficient lightbulbs and the re-emergence of reusable nappies (diapers). Given their ease of use, one might think that 'green' lightbulbs would become far more popular than reusable nappies and the associated inconvenience. However, this is not always the case. The paper takes a novel approach to understanding consumers' behaviour, using functional analysis to examine 'green' and 'normal' products and demonstrating why some refuse to use energy-efficient lightbulbs, despite using reusable nappies. It considers how consumer perceptions have developed and the implications for engineering designers.

Dynamo

Reliability at massive scale is one of the biggest challenges we face at Amazon.com, one of the largest e-commerce operations in the world; even the slightest outage has significant financial consequences and impacts customer trust. The Amazon.com platform, which provides services for many web sites worldwide, is implemented on top of an infrastructure of tens of thousands of servers and network components located in many datacenters around the world. At this scale, small and large components fail continuously and the way persistent state is managed in the face of these failures drives the reliability and scalability of the software systems. This paper presents the design and implementation of Dynamo, a highly available key-value storage system that some of Amazon's core services use to provide an "always-on" experience. To achieve this level of availability, Dynamo sacrifices consistency under certain failure scenarios. It makes extensive use of object versioning and application-assisted conflict resolution in a manner that provides a novel interface for developers to use.

Road-safety education: spatial decentering and subjective or objective picture processing

The current study examined children's ability to analyse pictures of a risky situation, both in relation to the characteristics of the pictures and in relation to the centering/decentering process of cognitive development. Sixty children aged 6, 9 or 11 years were given an objective or subjective version of a story about a risky situation involving road crossing and were asked to reconstruct it by putting six pictures in chronological order. The type of picture series, objective or subjective, had a different effect on the children's understanding and performance, according to the age. The older children were better at ordering the pictures, but on the subjective version only. The picture-version effect on planning time decreased with age; only the younger children took more time to start touching the pictures. On one hand, it is concluded that for the youngest children, objective representations are essential to analysing pictures showing a risk, whereas the oldest children will profit more from a subjective view. On the other hand, subjective representations, which give a more realistic view, provide an excellent tool for testing children's abilities. Subjective representations can be used to detect potentially risky behaviour in virtual situations (static pictures, or multimedia tools), since it permits one to predict at-risk behaviour in the street and to assess the effectiveness of remedial measures.

Object-Oriented Echo Perception and Cortical Representation in Echolocating Bats

Echolocating bats can identify three-dimensional objects exclusively through the analysis of acoustic echoes of their ultrasonic emissions. However, objects of the same structure can differ in size, and the auditory system must achieve a size-invariant, normalized object representation for reliable object recognition. This study describes both the behavioral classification and the cortical neural representation of echoes of complex virtual objects that vary in object size. In a phantom-target playback experiment, it is shown that the bat Phyllostomus discolor spontaneously classifies most scaled versions of objects according to trained standards. This psychophysical performance is reflected in the electrophysiological responses of a population of cortical units that showed an object-size invariant response (14/109 units, 13%). These units respond preferentially to echoes from objects in which echo duration (encoding object depth) and echo amplitude (encoding object surface area) co-varies in a meaningful manner. These results indicate that at the level of the bat's auditory cortex, an object-oriented rather than a stimulus-parameter–oriented representation of echoes is achieved.

The Probabilistic Nature of Objective Consequentialism

Abstract: Theorists have consistently maintained that the most plausible forms of objective consequentialism must be probabilistic if and only if indeterminism is true. This standard position, however popular, lacks sufficient motivation. Assume determinism to be true and an attempt will be made to show that attractive forms of objective consequentialism must be probabilistic ‐ and not for reasons related to our epistemic limitations either.Here it is argued that all extant objective formulations of consequentialism fail to deliver the normative implications that the spirit of objective consequentialism requires. My argument rests upon the claim that certain pairs of subjunctive conditionals with identical antecedents and incompatible consequents are such that neither of the pair is true.Upon leveling the objection, the concept of an “objective” subjunctive probability is introduced and utilized in the transformation of a subjective version of expected act utility consequentialism into an objective version, one that is capable of dealing with the difficulties posed by the objection. I end by indicating some ways in which the closest thing to a plausible, objective form of consequentialism might be developed.

Efficient segment-based video transcoding proxy for mobile multimedia services

To support various bandwidth requirements for mobile multimedia services for future heterogeneous mobile environments, such as portable notebooks, personal digital assistants (PDAs), and 3G cellular phones, a transcoding video proxy is usually necessary to provide mobile clients with adapted video streams by not only transcoding videos to meet different needs on demand, but also caching them for later use. Traditional proxy technology is not applicable to a video proxy because it is less cost-effective to cache the complete videos to fit all kinds of clients in the proxy. Since transcoded video objects have inheritance dependency between different bit-rate versions, we can use this property to amortize the retransmission overhead from transcoding other objects cached in the proxy. In this paper, we propose the object relation graph (ORG) to manage the static relationships between video versions and an efficient replacement algorithm to dynamically manage video segments cached in the proxy. Specifically, we formulate a transcoding time constrained profit function to evaluate the profit from caching each version of an object. The profit function considers not only the sum of the costs of caching individual versions of an object, but also the transcoding relationship among these versions. In addition, an effective data structure, cached object relation tree (CORT), is designed to facilitate the management of multiple versions of different objects cached in the transcoding proxy. Experimental results show that the proposed algorithm outperforms companion schemes in terms of the byte-hit ratios and the startup latency.

An optimal solution for caching multimedia objects in transcoding proxies

As audio and video applications have proliferated on the Internet, caching multimedia objects in transcoding proxies has become an important technology for adapting the same multimedia object to meet diverse needs of various mobile appliances. In this paper, the problem of caching multimedia objects in transcoding proxies, i.e., determining the proper versions of the same multimedia object to be cached at selective nodes in a network such that the specified objective is achieved, is addressed. First, a novel model, which is formulated as an optimization problem by combining both transcoding cost and transmission cost in a cooperative way, is presented. Second, an optimal solution is derived for computing the optimal locations, which is also extended to solve the problem of optimally deciding the locations for placing a fixed number of versions of the same multimedia object in a network since caching more objects will generate great overhead as well. Finally, the performance of the proposed model is evaluated on different performance metrics through extensive simulation experiments.

Aggregate Profit-Based Caching Replacement Algorithms for Streaming Media Transcoding Proxy Systems

This work derives a generalized video object profit function from the extended weighted transcoding graph to calculate the individual cache profit of certain versions of a video object, and the aggregate profit from caching multiple versions of the same video object. This proposed function takes into account the popularity of certain versions of an object, the transcoding delay among versions, and the average duration of access of each version. Based on the profit function, cache-replacement algorithms are proposed to reduce the startup delay and network traffic by efficiently caching video objects with the most profits. Two kinds of simulations were conducted to evaluate the performance of the proposed algorithms. These simulations exploit partial viewing traces and complete viewing traces, separately. The results demonstrate that the proposed algorithms outperform the competing algorithms by 15%-39% in delay saving ratio and 5%-10% in byte-hit ratio

Multimedia Object Placement for Transparent Data Replication

Transparent data replication is a promising technique for improving the system performance of a large distributed network. Transcoding is an important technology which adapts the same multimedia object to diverse mobile appliances; thus, users' requests for a specified version of a multimedia object could be served by a more detailed version cached according to transcoding. Therefore, it is particularly of theoretical and practical necessity to determine the proper version to be cached at each node such that the specified objective is achieved. In this paper, we address the problem of multimedia object placement for transparent data replication. The performance objective is to minimize the total access cost by considering both transmission cost and transcoding cost. We present optimal solutions for different cases for this problem. The performance of the proposed solutions is evaluated with a set of carefully designed simulation experiments for various performance metrics over a wide range of system parameters. The simulation results show that our solution consistently and significantly outperforms comparison solutions in terms of all the performance metrics considered

An information model for collaboration in the construction Industry

Collaborative work is an essential ingredient for success in the construction industry. With the advancements of capabilities of information technologies and communication infrastructures, the effective utilisation of these technologies has become very important and strongly affects business processes that have long followed traditional paths. This article describes the main characteristics of the concept-modelling framework that is developed in the DesKs project. Concept modelling gives end-users access to the schema of design models and provides a high level of flexibility for modelling. To support collaborative work, it provides remote data access and allows users to share resources that, instead of being exchanged or stored centrally, remain active at their source in tight relation with business processes. The main technical aspects of the concept-modelling framework are discussed. Object version control and timeline management of revisions of objects are used to increase the integrity between objects that are accessed and edited by multiple users across a network.

TH‐C‐330A‐04: Novel Learning‐Based Approach to Optimal EPID Image Deblurring and Enhancement

Purpose: Finite focal spot size in X‐ray imaging equipment has a blurring effect on acquired images. For practical reasons, it is neither possible nor desirable to reduce the spot size of medical linacs below a certain diameter. This affects task performance in IGRT, where the blurring of the edges of structures reduces positioning accuracy. Since the focal spot size and shape of linacs vary, the filter must be customized to a particular linac. We have developed an algorithm that learns to deblur portal images by comparing actual images to their Monte Carlo (MC) generated ideal counterparts. Method and Materials: A training object containing sharp edges of all orientations is imaged to capture the blurring and noise characteristics of the system. MC simulations in which a point source irradiates a digital version of the training object are used to generate ideal images. These are used as training data to optimize the convolution kernel that effects deblurring. Owing to the nature of the training data, the kernel will deblur the image as well as enhance edges. We assume since the object is 1m from the source, blurring is uniform for all transverse object planes. Results: Large samples of phantom and patient images were used to evaluate filter performance. A marked improvement in image quality is apparent. Evaluation of spatial resolution (MTF) and contrast‐to‐noise ratio (CNR) reveals a dramatic improvement in MTF but reduction in CNR. However, since the CNR remains above 70 at doses of 1MU, the increase in noise will not effect IGRT task performance. Conclusion: This work indicates the utility of this novel image enhancement technique in clinical images. In particular, visibility of small objects in images, such as prostate seeds, is remarkably enhanced.Conflict of Interest: Sponsored by Siemens.

An Effective Cache Replacement Algorithm in Transcoding-Enabled Proxies

In this paper, we address the problem of cache replacement for transcoding proxy caching. Transcoding proxy is a proxy that has the functionality of transcoding a multimedia object into an appropriate format or resolution for each client. We first propose an effective cache replacement algorithm for transcoding proxy. In general, when a new object is to be cached, cache replacement algorithms evict some of the cached objects with the least profit to accommodate the new object. Our algorithm takes into account of the inter-relationships among different versions of the same multimedia object, and selects the versions to replace according to their aggregate profit which usually differs from simple summation of their individual profits as assumed in the existing algorithms. It also considers cache consistency, which is not considered in the existing algorithms. We then present a complexity analysis to show the efficiency of our algorithm. Finally, we give extensive simulation results to compare the performance of our algorithm with some existing algorithms. The results show that our algorithm outperforms others in terms of various performance metrics.

Effects of varying stimulus size on object recognition in pigeons.

The authors investigated the pigeon's ability to generalize object discrimination performance to smaller and larger versions of trained objects. In Experiment 1, they taught pigeons with line drawings of multipart objects and later tested the birds with both larger and smaller drawings. The pigeons exhibited significant generalization to new sizes, although they did show systematic performance decrements as the new size deviated from the original. In Experiment 2, the authors tested both linear and exponential size changes of computer-rendered basic shapes to determine which size transformation produced equivalent performance for size increases and decreases. Performance was more consistent with logarithmic than with linear scaling of size. This finding was supported in Experiment 3. Overall, the experiments suggest that the pigeon encodes size as a feature of objects and that the representation of size is most likely logarithmic.

An efficient multiversion access control in a Temporal Object Oriented Database.

Many data base applications require the storage and manipulation of different versions of data objects. To satisfy the diverse needs of these applications, current database systems support versioning [Hulten94] at a very low level. The proposed model demonstrates that an application independent versioning can be supported significantly at higher level. The model uses signature patterns [Norvag99], hash table and B+ trees. The outcome of the analysis shows that the proposed model is performing well for all possible operations on versions.

Type-safe Versioned Object Query Language

The concept of versioning was initially proposed for controlling design evo- lution on computer aided design and software engineering. On the context of database systems, versioning is applied for managing the evolution of different elements of the data. Modern database systems provide not only powerful data models but also complex query languages that have evolved to include several features from complex program- ming languages. While most related work focuses on different aspects of the concepts, designing models, and processing of versions efficiently, there is yet to be a formal definition of a query language for database systems with versions control. In this work we propose a query language, named Versioned Object Query Language (VOQL), that extends ODMG Object Query Language (OQL) with new features to recover object versions. We provide a precise definition of VOQL through a type system and we prove it safe in relation to a small-step operational semantics. Finally, we validate the proposed definition by implementing an interpreter for VOQL.

Consistency of a Shared Versioned Model for Distributed Cooperation

: In the A/E/C planning process, expert teams of different disciplines create solutions that are interdependent to a high degree. As a rule the ultimate solution needs many iteration steps. Available CAD-systems support synchronous and distributed work on a document base. Therefore, cooperation between the engineers can be obtained only by the exchange of documents. It is generally known that an overall consistency of the planning material is not adequately addressed by this approach. In this article a solution approach focused upon consistency of the shared planning material in a distributed CAD environment is presented. Because of the nature of the planning process, version management is applied on an object basis. Project data are stored as object versions and relationships. The operations for the distributed cooperation are identified and their impact on the project data is described formally, using logical expressions and set theory. A formulation based upon an algebra of sets is presented.

A horse of a different colour: Do patients with semantic dementia recognise different versions of the same object as the same?

Ten patients with semantic dementia resulting from bilateral anterior temporal lobe atrophy, and 10 matched controls, were tested on an object recognition task in which they were invited to choose (from a four-item array) the picture representing “the same thing” as an object picture that they had just inspected and attempted to name. The target in the response array was never physically identical to the studied picture but differed from it – in the various conditions – in size, angle of view, colour or exemplar (e.g. a different breed of dog). In one test block for each patient, the response array was presented immediately after the studied picture was removed; in another block, a 2 min filled delay was inserted between study and test. The patients performed relatively well when the studied object and target response differed only in the size of the picture on the page, but were significantly impaired as a group in the other three type-of-change conditions, even with no delay between study and test. The five patients whose structural brain imaging revealed major right-temporal atrophy were more impaired overall, and also more affected by the 2 min delay, than the five patients with an asymmetric pattern characterised by predominant left-sided atrophy. These results are interpreted in terms of a hypothesis that successful classification of an object token as an object type is not a pre-semantic ability but rather results from interaction of perceptual and conceptual processing.

Coordinated enroute multimedia object caching in transcoding proxies for tree networks

Transcoding is a promising technology that allows systems to effect a quality-versus-size tradeoff on multimedia objects. As audio and video applications have proliferated on the Internet, caching in transcoding proxies has become an important technique for improving network performance, especially in mobile networks. This article addresses the problem of coordinated enroute multimedia object caching in transcoding proxies for tree networks. We formulate this problem as an optimization problem based on our proposed model, in which multimedia object caching decisions are made on all enroute caches along the routing path by integrating both object placement and replacement policies and cache status information along the routing path of a request is used to determine the optimal locations for caching multiple versions of the same multimedia object. We propose an optimal solution using dynamic programming to compute the optimal locations. We also extend this solution to solve the same problem for several constrained cases, including constraints on the cost gain per node and on the number of versions to be placed. Our model is evaluated on different performance metrics through extensive simulation experiments. The implementation results show that our model significantly outperforms existing models that consider Web caching in transcoding proxies either on a single path or at individual nodes.