Least fresh first cache replacement policy for NDN-based IoT networks

In-network caching in Named Data Networking (NDN) based Internet of Things (IoT) plays a central role for efficient data dissemination. Data cached throughout the network may quickly become obsolete as they are transient and frequently updated by their producers. As such, NDN-based IoT networks impose stringent requirement in terms of data freshness. While various cache replacement policies were proposed, none has considered the cache freshness requirement. In this paper, we introduce a novel cache replacement policy called Least Fresh First (LFF) integrating the cache freshness requirement. LFF evicts invalid cached contents based on time series forecasting of sensors future events. Extensive simulations are performed to evaluate the performance of LFF and to compare it to the different well-known cache replacement policies in ICN-based IoT networks. The obtained results show that LFF significantly improves data freshness compared to other policies, while enhancing the server hit reduction ratio, the hop reduction ratio and the response latency.     

Deep freezing to maintain the freshness of pork loin during long-term storage

Food Science and Biotechnology - As storage temperature impacts frozen meat quality, we evaluated the ideal freezing and storage temperatures for pork loin, and effects of long-term storage...     

VIS/NIR spectroscopy for non-destructive freshness assessment of Atlantic salmon (Salmo salar L.) fillets

Visible/near-infrared spectroscopy has been evaluated for use in freshness prediction and frozen-thawed classification of farmed Atlantic salmon fillets, where fresh samples were stored as whole fish in ice. A handheld interactance probe for performing rapid measurements of single fillets and an imaging spectrometer for online analysis at an industrial speed of one fillet per second, have been used. Freshness as storage days in ice is predicted with an accuracy of 2.4 days for individual fillets, whereas frozen-thawed salmon fillets are completely separated from fresh fillets. The prediction results are comparable to previous results using the Quality Index Method with trained panelists. The region between 605 and 735 nm, which excludes interference by carotenoids and water, is appropriate for both frozen-thawed classification and freshness prediction of salmon fillets. The results indicate that the spectral changes are explained mainly by oxidation of heme proteins during the freeze–thaw cycle and during chilled storage in ice.     

新鲜度敏感的上下文推理实时调度算法

由于普适计算中上下文具有时效性,上下文推理器必须支持推理任务的实时调度。针对上下文推理结果在一段时间内仍然保持新鲜的特点,本文提出推理结果重复利用效率及其计算公式。在此基础上提出一种新鲜度敏感的上下文推理实时调度算法FRSA,以推理结果重复利用效率作为判断依据结合任务的deadline进行调度,其目标是在推理器负载较重时达到较高吞吐量。实验表明,在推理器负载重时,FRSA的系统吞吐量比经典调度算法(SJF,EDF,LSF和FCFS)高出10%-30%。     

Colorimetric assay for determination of trimethylamine-nitrogen (TMA-N) in fish by combining headspace-single-drop microextraction and microvolume UV–vis spectrophotometry

In this work, headspace-single-drop microextraction has been used in combination with microvolume UV–vis spectrophotometry to enhance the determination of trimethylamine-nitrogen (TMA-N) in fish samples. TMA-N is often used for monitoring fish freshness, but due to the low analytical sensitivity usually achieved, its determination must be performed after certain time of storage in some fish species. The proposed methodology, based on the extraction and subsequent complexation of volatile TMA-N onto a picric acid-containing xylene microdrop exposed to the headspace, involves an important improvement of sensitivity (detection limit 6 × 10⁻⁴ mg TMA-N per 100 g of fish), a miniaturization of the AOAC Official Method (971.14) and a simple approach for routine labs. This method is well suited to determination of TMA-N in different species of frozen and fresh fish samples from markets and to study the evolution of TMA-N concentration in farmed turbot at the earliest stages of deterioration.     

Chemical and microbiological quality of grass carp (Ctenopharyngodon idella) slaughtered by different methods

The effect of two slaughter methods (immersion in ice-water slurry and electrical stunning followed by ice slurry asphyxiation) on chemical and microbiological parameters of grass carp (Ctenopharyngodon idella) stored in ice for 20 days was evaluated. No differences in total volatile basic nitrogen (TVB-N), pH, carbohydrate or protein content of mucus were observed between the slaughter methods. Ice-slaughtered fish had lower bacteria counts at the beginning of storage, but higher counts than fish slaughtered by electricity at the end of storage (p < 0.05). However, no significant differences in the shelf life were observed between the slaughter methods evaluated (limit of acceptability – counts > 3 × 10⁶ CFU g⁻¹ – attained after 13–16 days). Results indicated that the chemical parameters evaluated have a limited applicability to assess the shelf life of grass carp stored in ice, since pH limit (6.8) was exceeded after 4 days, while TVB-N limit (30 mg%) was not attained after 20 days of storage.     

Automatic freshness assessment of cod (Gadus morhua) fillets by Vis/Nir spectroscopy

VIS/NIR spectroscopy for differentiating between fresh and frozen-thawed cod fillets and for assessing the freshness as days on ice has been evaluated. Both a handheld interactance probe for doing quick measurements of single fillets and an imaging spectrometer for doing online analysis at industrial speed of one fillet per second, have been used. Results show that frozen-thawed cod fillets can be fully separated from fresh fillets using a small subset of wavelengths in the visible region. Freshness as days on ice can be determined with an accuracy of 1.6 days on individual fillets. The results indicate that oxidation of hemoglobin and myoglobin during freezing-thawing and cold storage on ice are explaining most of the variations seen in the visible region of the spectrum.     

Evaluation of chicken freshness using a low-cost colorimetric sensor array with AdaBoost–OLDA classification algorithm

This paper attempted to evaluate chicken freshness using a low-cost colorimetric sensor array with the help of a classification algorithm. We fabricated a novel and low-cost colorimetric sensors array, with a specific colorific fingerprint to volatile compounds, using printing chemically responsive dyes on a C2 reverse silica-gel flat plate. In addition, we proposed a novel classification algorithm for sensors data classification – orthogonal linear discriminant analysis (OLDA) and adaptive boosting (AdaBoost) algorithm, namely AdaBoost–OLDA. And we compared it with two classical classification algorithms – linear discriminant analysis (LDA) and back propagation artificial neural network (BP-ANN). Experimental results showed classification results by AdaBoost–OLDA algorithm is superior to BP-ANN and LDA algorithms, the classification results by which are both 100% in the calibration and prediction sets. This study sufficiently demonstrated that the colorimetric sensors array with a classification algorithm has a high potential in evaluating chicken freshness, and AdaBoost–OLDA algorithm has a strong performance in solution to a complex data classification.     

Quality of Crude Oil Extracted from Aging Walleye Pollock (<Emphasis Type="Italic">Theragra chalcogramma</Emphasis>) Byproducts

The quality of crude oil was examined as a function of the temperature and delay time between collecting and processing the fish byproducts from a commercial cannery into crude oil. Extracts from pollock byproducts stored at 6 and 15 °C for up to 4 and 10 days was examined. Longer storage of byproducts resulted in higher free fatty acid (FFA) and an increase in retinol levels in the extracted crude oils. Primary and secondary oxidation assays consisting of peroxide value and thiobarbituric acid-reactive substances increased initially with storage time on day 1 followed by an unexpected decrease with storage time. Higher storage temperature resulted in greater FFA and retinol levels, but lower oxidation products in the crude oils. The tocopherol levels decreased with storage time of the byproducts with no differences between the storage temperatures. Eicosapentaenoic acid, docosahexaenoic acid and polyunsaturated fatty acids percentage remained similar in the extracted oils with the respective storage time or temperature treatments.