Similarity queries: their conceptual evaluation, transformations, and processing

Many application scenarios can significantly benefit from the identification and processing of similarities in the data. Even though some work has been done to extend the semantics of some operators, for example join and selection, to be aware of data similarities, there has not been much study on the role and implementation of similarity-aware operations as first-class database operators. Furthermore, very little work has addressed the problem of evaluating and optimizing queries that combine several similarity operations. The focus of this paper is the study of similarity queries that contain one or multiple first-class similarity database operators such as Similarity Selection, Similarity Join, and Similarity Group-by. Particularly, we analyze the implementation techniques of several similarity operators, introduce a consistent and comprehensive conceptual evaluation model for similarity queries, and present a rich set of transformation rules to extend cost-based query optimization to the case of similarity queries.     

Assessment of Fire Risk in the Readymade Garment Industry in Dhaka,Bangladesh

Readymade garments are the most important export item from Bangladesh, yet the working conditions and fire safety records in the factories are often not up to the standard. Despite a number of initiatives to curb fire accidents in the garment industry, there are still a significant number of fire occurrences in this industry. Unfortunately, there is no comprehensive statistics on the current status of fire provisions and management practices in the readymade garment factories in Bangladesh. Given the management practices (soft issues) are often as important as structural fire safety measures, yet difficult to regulate, this paper develops a fire risk index (FRI), the first of its kind in Bangladesh, for soft parameters in the garment industry. FRI for 60 random garment factories are developed through surprise inspections to understand the current status of fire risk due to inadequacies in the soft parameters. Results show that the mean FRI is 2.8 on a scale of 5.0, which indicates an alarming condition. Locked exit doors, lack of emergency announcement system and lack of fire drills are the three worst performers among the 24 investigated parameters and require immediate attention from the regulators and stakeholders. We also observed a U-shaped relationship between FRI and factory size. Factories that are members of the industry’s trade lobby generally have better fire safety practices than the non-members. Given the importance of the readymade garment sector in many developing countries, poor fire safety record and lack of information on fire safety, our approach of developing an FRI for the industry can be very useful to understand the immediate concerns and thus to curb fatalities and injuries from fire accidents in this sector.     

The effect of mincing method on the quality of refrigerated whiting burgers

Different mincing methods in the preparation of refrigerated whiting burgers had a significant effect on the products' quality during storage ( P  < 0.05). The burgers containing pre-cooked mince products (PCMP) had the lowest microbial load with longest sensory shelf life (10 days). Oven drying of dry ingredients with subsequent hygienic practices markedly decreased microbial load in final products, from 5.30 to <1.47 log CFU g⁻¹ for PCMP, 5.80–2.45 log CFU g⁻¹ for washed mince products (WMP), 5.65–2.14 log CFU g⁻¹ for unwashed mince products. The lowest trimethylamine and total volatile basic nitrogen (TVB-N) were observed with WMP reaching 14.7 and 42.03 mg per 100 g, respectively, at the end of storage. The differences in average surface colours of samples with different preparations and different additives were significant after mincing, but decreased after addition of ingredients, and after cooking. This study indicates the possibility of using pre-cooking as a method for formulated fish mince-based products as it had the highest consumer acceptance as well as longer sensory shelf life despite its higher values of trimethylamine and TVB-N compared with WMP.     

Vanadium pentoxide film for microsecond pulse generation in 1.5-μm region

Q-switched erbium doped fiber laser(EDFL) was passively realized using vanadium pentoxide(V₂O₅) embedded into polyethylene glycol(PEG) film as saturable absorber(SA). The laser could successfully generate stable self-starting pulses when the V₂O₅ film was placed in an EDFL cavity. It operated at 1 562.4 nm wavelength. The repetition rate can be varied from 91.7 kHz to 128.2 kHz while the pulse width shrank from 10.90 μs to 7.81 μs with rising pump powe...     

Securing Cloud Storage by Remote DataIntegrity Check with Secured Key Generation

In recent decades, a number of protocols for Remote data integrity checking (RDIC) have been proposed.Identity (ID) based RDIC protocols are constructed to guarantee cloud data integrity and data privacy. The known protocols for RDIC always assume that the Private key generator (PKG) is a trusted one, but in real-world applications by corrupt PKG, malicious Cloud server (CS) can easily cheat the third party auditor that the data owner's outsourced data are kept safe through the data has been deleted or altered. In this paper, we explore the novel model of RDIC with untrusted PKG and malicious CS, by employing the partial key method and Authentication, authorization, accounting (AAA) service. We construct a new ID-based RDIC, which provides the ID revocation and key updation. The experimental evaluations show that our scheme is more efficient than known ones.     

Study on brittleness templates for shale gas reservoirs-A case study of Longmaxi shale in Sichuan Basin,southern China

Differentiating brittle zones from ductile zones in low permeability shale formations is imperative for efficient hydraulic fracturing stimulation.The brittlene...     

Active vibration control of smart plates using directional actuation and sensing capability of piezoelectric composites

The efficacy of directional actuation and sensing using piezoelectric fiber-reinforced composite (PFRC) actuators and sensors in active vibration suppression is examined for the first time for smart fiber metal laminate (FML) plates. A recently developed quadrilateral element with four physical nodes and one electric node, based on an efficient layer-wise theory, is employed for the structural analysis. The linear quadratic Gaussian (LQG) control strategy is employed for the active vibration control. The optimal direction of PFRC fibers to achieve the minimum control voltage is obtained for skew plates of cantilever and simply supported boundary conditions for different skew angles.