Coping with production time variability via dynamic lead-time quotation

In this paper, we propose two dynamic lead-time quotation policies in an M/GI/1 type make-to-stock queueing system serving lead-time sensitive customers with a single type of product. Incorporating non-exponential service times in an exact method for make-to-stock queues is usually deemed difficult. Our analysis of the proposed policies is exact and requires the numerical inversion of the Laplace transform of the sojourn time of an order to be placed. The first policy assures that the long-run probability of delivering the product within the quoted lead-time is the same for all backlogged customers. The second policy is a refinement of the first which improves the profitability if customers are oversensitive to even short delays in delivery. Numerical results show that both policies perform close to the optimal policy that was characterized only for exponential service times. The new insight gained is that the worsening impact of the production time variability, which is felt significantly in systems accepting all customers by quoting zero lead times, decreases when dynamic lead-time quotation policies are employed

Evolution of Software Testing Strategies and Trends: Semantic Content Analysis of Software Research Corpus of the Last 40 Years

From the early days of computer systems to the present, software testing has been considered as a crucial process that directly affects the quality and reliability of software-oriented products and services. Accordingly, there is a huge amount of literature regarding the improvement of software testing approaches. However, there are limited reviews that show the whole picture of the software testing studies covering the topics and trends of the field. This study aims to provide a general figure reflecting topics and trends of software testing by analyzing the majority of software testing articles published in the last 40 years. A semi-automated methodology is developed for the analysis of software testing corpus created from core publication sources. The methodology of the study is based on the implementation of probabilistic topic modeling approach to discover hidden semantic patterns in the 14,684 published articles addressing software testing issues between 1980 and 2019. The results revealed 42 topics of the field, highlighting five software development ages, namely specification, detection, generation, evaluation, and prediction. The recent accelerations of the topics also showed a trend toward prediction-based software testing actions. Additionally, a higher trend on the topics concerning “Security Vulnerability”, “Open Source” and “Mobile Application” was identified. This study showed that the current trend of software testing is towards prediction-based testing strategies. Therefore, the findings of this study may provide valuable insights for the industry and software communities to be prepared for the possible changes in the software testing procedures using prediction-based approaches.publishedVersio

Seamless video access for mobile devices by content-aware utility-based adaptation

Today's Internet multimedia services are characterized by heterogeneous networks, a wide range of terminals, diverse user preferences, and varying natural environment conditions. Heterogeneity of terminals, networks, and user preferences impose nontrivial challenges to the Internet multimedia services for providing seamless multimedia access particularly for mobile devices (e.g., laptops, tablet PCs, PDAs, mobile phones, etc.). Thus, it is essential that advanced multimedia technologies are developed to deal with these challenges. One of these technologies is video adaptation, which has gained significant importance with its main objective of enabling seamless access to video contents available over the Internet. Adaptation decision taking, which can be considered as the "brain" of video adaptation, assists video adaptation to achieve this objective. Scalable Video Coding (SVC) offers flexibility for video adaptation through providing a comprehensive set of scalability parameters (i.e., temporal, spatial, and quality) for producing scalable video streams. Deciding the best combination of scalability parameters to adapt a scalable video stream while satisfying a set of constraints (e.g., device specifics, network bandwidth, etc.) poses challenges for the existing adaptation services to enable seamless video access. To ease such challenges, an adaptation decision taking technique employing a utility-based approach to decide on the most adequate scalability parameters for adaptation operations is developed. A Utility Function (UF), which models the relationships among the scalability parameters and weights specifying the relative importance of these parameters considering video content characteristics (i.e., motion activity and structural feature), is proposed to assist the developed technique. In order to perform the developed adaptation decision taking technique, a video adaptation framework is also proposed in this paper. The adaptation experiments performed using the proposed framework prove the effectiveness of the framework to provide an important step towards enabling seamless video access for mobile devices to enhance viewing experience of users. © 2012 Springer Science+Business Media, LLC

Modeling user perception of 3D video based on ambient illumination context for enhanced user centric media access and consumption

For enjoying 3D video to its full extent, it is imperative that access and consumption of it is user centric, which in turn ensures improved 3D video perception. Several important factors including video characteristics, users’ preferences, contexts prevailing in various usage environments, etc have influences on 3D video perception. Thus, to assist efficient provision of user centric media, user perception of 3D video should be modeled considering the factors affecting perception. Considering ambient illumination context to model 3D video perception is an interesting research topic, which has not been particularly investigated in literature. This context is taken into account while modeling video quality and depth perception of 3D video in this paper. For the video quality perception model: motion and structural feature characteristics of color texture sequences; and for the depth perception model: luminance contrast of color texture and depth intensity of depth map sequences of 3D video are used as primary content related factors in the paper. Results derived using the video quality and depth perception models demonstrate that these models can efficiently predict user perception of 3D video considering the ambient illumination context in user centric media access and consumption environments

An expandable approach for design and personalization of digital, just-in-time adaptive interventions

Objective: We aim to deliver a framework with 2 main objectives: 1) facilitating the design of theory-driven, adaptive, digital interventions addressing chronic illnesses or health problems and 2) producing personalized intervention delivery strategies to support self-management by optimizing various intervention components tailored to people's individual needs, momentary contexts, and psychosocial variables

Giant Hydatid Cyst Originating from Psoas Muscle Extending to the Iliac Bone, Inguinal, and Femoral Canals: A Case Report and Current Literature Review

Retroperitoneal hydatid cysts are extremely rare and difficult to distinguish from other intra-abdominal pathologies, such as synovial sarcoma. In this study, we present a rare case of a complicated retroperitoneal hydatid cyst originating from the psoas muscle without any other focus. A 59-year-old male patient presented to the outpatient clinic with complaints of constipation and a feeling of gradually increasing swelling in the left lower quadrant of the abdomen and left groin area, progressing toward the left leg. In the examinations performed, a multiloculated giant hydatid cyst that filled the left pelvis in the retroperitoneal region, deviated the intra-abdominal organs to the right side, and extended to the left femoral and inguinal canals was detected. The patient underwent surgical excision and was followed up during the postoperative period. No evidence of recurrence was found at the patient’s 3rd and 6th month follow-ups. Primary muscle hydatid cysts necessitate a distinct approach to treatment and management when compared with hydatid cysts in other bodily organs. While recurrences remain a potential concern after resection, it is noteworthy that the window for the formation of fertile cysts typically spans up to 10 months. Thus, it is advisable to conduct regular postoperative follow-up examinations during the first year following surgery to ensure comprehensive monitoring and care

Monocyte/high-density lipoprotein ratio predicts the mortality in ischemic stroke patients

Objective The inflammatory process is a very important stage in the development and prognosis of acute ischemic stroke (AIS). The monocyte to high-density lipoprotein (HDL) ratio (MHR) is accepted as a novel marker for demonstrating inflammation. However, the role of MHR as a predictor of mortality in patients with AIS remains unclear. Methods We retrospectively enrolled 466 patients who were referred to our clinic within the first 24hours of symptom presentation and who were diagnosed with AIS between January 2008 and June 2016. Four hundred and eight controls of similar age and gender were also included. The patient group was classified into two groups according to 30-day mortality. The groups were compared in terms of monocyte counts, HDL, and MHR values. Results The patient group had significantly higher monocyte counts and lower HDL levels; therefore, this group had higher values of MHR compared to controls. Additionally, the monocyte count and MHR value were higher, and the HDL level was lower in non-surviving patients (p<0.001). The MHR value was also observed as a significant independent variable of 30-day mortality in patients with AIS (p<0.001). The optimum cut-off value of MHR in predicting the 30-day mortality for patients with AIS was 17.52 (95% CI 0.95–0.98). Conclusion Our study demonstrated that a high MHR value is an independent predictor of 30-day mortality in patients with AIS

Improving scalable video adaptation in a knowledge-based framework

In a knowledge-based content adaptation framework, video adaptation can be performed in a series of steps, named conversions. The high-level decision phase in such a framework occasionally encounters several feasible parameter values of a specific conversion. This paper proposes to transfer further decisions to a low-level phase that decides which parameters maximise the quality of the adaptation. Particularly when more than one solution are available, an innovative quality measure is used for selecting the best values for the parameters among the set of values that fulfil the adaptation constraints in the case of scalable vide