Search

Soil salinity is a growing problem in agriculture, plant growth regulators (PGRs) can regulate plant response to stress. The objective of this study was to evaluate the effects of exogenous 6-benzyladenine (6-BA) on photosynthetic capacity and antioxidant defences in watermelon (Citrullus lanatus L.) seedlings under NaCl stress. Two watermelon genotypes were subjected to four different treatments: (1) normal water (control); (2) 20 mg L−1 6-BA; (3) 120 mmol L−1 NaCl; and (4) 120 mmol L−1 NaCl + 20 mg L−1 6-BA. Our results showed that NaCl stress inhibited the growth of watermelon seedlings, decreased their photosynthetic capacity, promoted membrane lipid peroxidation, and lowered the activity of protective enzymes. Additionally the salt-tolerant Charleston Gray variety fared better than the salt-sensitive Zhengzi NO.017 variety under NaCl stress. Foliar spraying of 6-BA under NaCl stress significantly increased biomass accumulation, as well as photosynthetic pigment, soluble sugar, and protein content, while decreasing malondialdehyde levels, H2O2 content, and electrolyte leakage. Moreover, 6-BA enhanced photosynthetic parameters, including net photosynthetic rate, stomatal conductance, intercellular CO2 concentration, and transpiration rate; activated antioxidant enzymes, such as superoxide dismutase, catalase, and peroxidase; and improved the efficiency of the ascorbate-glutathione cycle by stimulating glutathione reductase, dehydroascorbate reductase, and monodehydroascorbate reductase, as well as ascorbic acid and glutathione content. Principal component analysis confirmed that 6-BA improved salt tolerance of the two watermelon varieties, particularly Zhengzi NO.017, albeit through two different regulatory mechanisms. In conclusion, 6-BA treatment could alleviate NaCl stress-induced damage and improve salt tolerance of watermelons by regulating photosynthesis and osmoregulation, activating the ascorbate-glutathione cycle, and promoting antioxidant defences.

The ECG classification processor is a key component in wearable intelligent ECG monitoring devices which monitor the ECG signals in real time and detect the abnormality automatically. The state-of-the-art ECG classification processors for wearable intelligent ECG monitoring devices are faced with two challenges, including ultra-low energy consumption demand and high classification accuracy demand against patient-to-patient variability. To address the above two challenges, in this work, an ultra-energy-efficient ECG classification processor with high classification accuracy is proposed. Several design techniques have been proposed, including a reconfigurable SNN/ANN inference architecture for reducing energy consumption while maintaining classification accuracy, a reconfigurable on-chip learning architecture for improving the classification accuracy against patent-to-patient variability, and a dual-purpose binary encoding scheme of ECG heartbeats for further reducing the energy consumption. Fabricated with a 28nm CMOS technology, the proposed design consumes extremely low classification energy (0.3μJ) while achieving high classification accuracy (97.36%) against patient-to-patient variability, outperforming several state-of-the-art designs.

South Asia is a hub for encompassing air contamination, with 37 of the top tiers of the 40 most contaminated urban communities around the globe (IQAIR, 2020). From this perspective, this research aims to explore the validity of the Environmental Kuznets Curve while controlling for the impacts of technological innovation and energy consumption on the sustainable economic growth–environmental pollution nexus in the backdrop of South Asian economies by using panel dataset from 1998 to 2018. Therefore, this analysis adopts a fully modified ordinary least square (FMOLS) approach for examination, which affirms the EKC hypothesis existence, suggesting that the environment in South Asia is deteriorating while technological innovations have moderated the impact. Moreover, the empirical findings indicate that energy consumption as well as technological innovations both have a significant positive impact on the CO2 emanations, which harms biodiversity.

At the present time, it is of major significance to study the solid-liquid-gas three-phase coupling relationship of coal, water, and gas in deep-mining stopes in order to prevent and control coal and gas outbursts in high-gas mines. In this study, the influence rules of water on the mechanical characteristics of coal, as well as gas diffusion and migration processes, was examined by combining theoretical analysis and laboratory testing procedures. The results showed that with increases in water content, the mechanical characteristics of coal bodies presented change trends of first increasing and then decreasing. In this study, it was found that the water content levels which corresponded to the maximum shear strength of the coal in the No. 8 coal seam in the study area had ranged between 6.77% and 11.9%, and the water content level corresponding to the extreme point was 8.66%. It was observed that under different water content conditions, the gas desorption speeds of the coal bodies gradually decreased over time. The gas desorption speeds rapidly decreased during the initial desorption stage and then gradually decreased over time. Furthermore, under the different water content conditions, the amount of gas desorption in the coal bodies was observed to gradually increase over time, with the initial desorption amounts displaying rapid increases. Then, with the passage of time, the increase speeds of the gas desorption amount gradually decreased and finally tended to remain at a stable value. It was found that with the increases in water content, the desorption speeds, initial desorption speeds, and desorption amount of gas in the coal bodies continuously decreased. In other words, the water content levels in the coal bodies were negatively correlated with the gas desorption speeds and desorption amounts of the coal bodies. In addition, the gas desorption speeds, initial desorption speeds, and desorption amounts were observed to change more sharply with the increases in water content. The results of this research hold important guiding significance for the improvement of the understanding of the mechanical properties of high-gas coal seams and the implementation of effective gas control measures.

The Chengdu-Chongqing urban agglomeration (CUA) faces considerable air quality concerns, although the situation has improved in the past 15 years. The driving effects of population, land and economic urbanization on PM2.5 concentrations in the CUA have largely been overlooked in previous studies. The contributions of natural and socio-economic factors to PM2.5 concentrations have been ignored and the spillover effects of multi-dimensional urbanization on PM2.5 concentrations have been underestimated. This study explores the spatial dependence and trend evolution of PM2.5 concentrations in the CUA at the grid and county level, analyzing the direct and spillover effects of multi-dimensional urbanization on PM2.5 concentrations. The results show that the mean PM2.5 concentrations in CUA dropped to 48.05 μg/m3 at an average annual rate of 4.6% from 2000 to 2015, however, in 2015, there were still 91% of areas exposed to pollution risk (&gt, 35 μg/m3). The PM2.5 concentrations in 92.98% of the area have slowly decreased but are rising in some areas, such as Shimian County, Xuyong County and Gulin County. The PM2.5 concentrations in this region presented a spatial dependence pattern of “cold spots in the east and hot spots in the west”. Urbanization was not the only factor contributing to PM2.5 concentrations. Commercial trade, building development and atmospheric pressure were found to have significant contributions. The spillover effect of multi-dimensional urbanization was found to be generally stronger than the direct effects and the positive impact of land urbanization on PM2.5 concentrations was stronger than population and economic urbanization. The findings provide support for urban agglomerations such as CUA that are still being cultivated to carry out cross-city joint control strategies of PM2.5 concentrations, also proving that PM2.5 pollution control should not only focus on urban socio-economic development strategies but should be an integration of work optimization in various areas such as population agglomeration, land expansion, economic construction, natural adaptation and socio-economic adjustment.

Warranty claims forecasting plays an increasingly important role not only for preparing financial plans but also for optimizing warranty policy and improving after-sale services. In the case of new products, an important feature is that the new generation of products often has a close connection with the previous generations of products it replaces. Thus, the warranty claims data of the previous generations of products can be used for extracting reliability information of new products. In this context, we propose a warranty claims forecasting model considering usage rate for new products sold with a two-dimensional warranty. The accelerate failure time model is introduced to investigate the effect of usage rate on product degradation. The non-homogeneous Poisson process is used to model failure counts of repairable products and the constrained maximum likelihood estimation method is used to estimate model parameters. The results of data experiments based on both simulation and real data collected from an automobile manufacturer in China show that the proposed model considering the varying usage rate outperforms the traditional models in forecasting the number of warranty claims.

Offering appropriate preventive maintenance strategy has an effective impact on achieving higher customer satisfaction. This article presents a flexible preventive maintenance strategy, where customers are grouped into two groups according to their usage rates, and then different preventive maintenance programs are applied to different types of customers. The product follows a two-dimensional failure process and the preventive maintenance cost is shared between the manufacturer and customer on a pro rata basis. The manufacturer’s warranty cost is minimized by jointly optimizing the pro rata proportion of the preventive maintenance cost, the preventive maintenance number and the corresponding preventive maintenance levels. Numerical experiments are presented to illustrate the effectiveness of the proposed approach. Results prove that the flexible preventive maintenance strategy outperforms the conventional unified preventive maintenance strategy in terms of total warranty cost. Besides, some managerial suggestions are also given to provide guidance of implementing the proposed preventive maintenance strategy.

Product warranty in the market has a significant role in both protection and promotion. The manufacturer faces a problem of optimizing the warranty period considering a trade-off between the warranty cost and marketing competition. Meanwhile, for a two-dimensional (2D) warranty, customers with different usage rates have various perceptions on warranty period. Based on the relationships between nominal usage rate and customer’s usage rates, three different cases of designed 2D warranty period are discussed. Considering the variations in customers perceptions, a demand function based on attractiveness index is proposed to describe the boosted sales volume. Meanwhile, the expected warranty cost of 2D warranty based on a bivariate approach is derived when the product failures are minimally repaired. A profit model is developed to estimate the manufacturer’s expected profit of providing a longer warranty period. The optimal extension of 2D base warranty period is obtained by maximizing the manufacturer’s expected profit. Numerical examples in the automobile market are also conducted to validate the proposed model.

Traditionally, a two-dimensional (2D) warranty is characterized by a single 2D warranty region with age limit as the x-axis and usage limit as the y-axis. However, customers with heterogeneous usage rate have various perceptions on the same 2D warranty region, which leads to dissatisfaction on warranty policy. This study proposes a customized 2D warranty menu for customers with heterogeneous usage rates to increase customers’ satisfaction on after-sales service. Customers are classified into several categories according to their usage rates, and the optimal 2D warranty regions in the menu are designed considering both the manufacturer’s total expected warranty cost and heterogeneous customers’ perceptions on the designed 2D warranty menu. We define an attractiveness index to quantify a customer’s perception on the 2D warranty region based on his usage rate. Meanwhile, design principles and procedures of designing the appropriate 2D warranty menu are proposed. By adopting the proposed menu, customer population has a better perception than a single region. Meanwhile, the manufacturer is more competitive by providing the proposed menu with a same total expected warranty cost.

Surface functionalization of nanomaterials with highly specific recognition elements, such as biomolecules and organic molecules, has made possible many novel nanosensors for bio/chemical analysis and target bioimaging. In this report, a fluorescent nanosensor which exhibits highly specific recognition capability towards Zn

For products with a two-dimensional (2D) warranty policy, customers are heterogeneous on usage rates. In this study, we propose a systematic warranty-reliability-price combination decision model for repairable products with a 2D Free Replacement-Repair Warranty (FRW). The effects of customers’ heterogeneous usage rate on both reliability design and the demand function of 2D warranted products are considered in the model. The optimal warranty-reliability-price combination is obtained by maximizing total expected profits over products’ life cycle. Two marketing scenarios are discussed, i.e., a stable market and a dynamic market. The optimality conditions for the two scenarios are investigated. The applicability of the model is demonstrated via a case study of an industrial 3D printer manufacturer, and it shows the consistency of the model.

Understanding the field reliability of a sold product is crucial to both managers and engineers for monitoring product quality and improving warranty service design. When practitioners model warran...

Product prices fluctuate dynamically with changes in market supply and demand. This poses a dilemma for dealers, that is, dealers need to establish a dynamic extended warranty (EW) pricing strategy based on the fluctuations in product prices to attract consumers. To address this challenging issue, we establish a dynamic integration model to derive optimal product prices and two-dimensional (2D) EW prices in a multistage dynamic market environment to maximize the dealer’s expected discounted profit during the product life cycle. In order to explore the dynamic influence mechanism between reliability engineering factors and market elements, this model combines the warranty cost model influenced by reliability related repair learning characteristics and the 2D EW demand model influenced by product price fluctuations. The model allows dealers to identify the relationships among various factors, including repair learning characteristic, production scale effect, product cost, EW cost in product reliability level, and fluctuating product demand and EW demand in market demand level, and more important, their effects, on the dealers’ profit. The necessary optimality conditions and case study are conducted for static and dynamic markets.

Warranties are prevalent in the market. The manufacturer of products sold with warranties often faces a problem of balancing a trade-off between warranty cost and boosted demand by warranties when ...

Design of experiments has received much attention in the context of reliability improvement. Many engineers and researchers are considering how to use designed experiments to improve the reliability of products and processes. This work illustrates a 12-run Plackett-Burman design and its analysis to improve the reliability of a diamond drill bit. A detailed description and execution of the design are provided including how to choose the factors and determine the number of experimental factors. In addition, the results of the real-world experiment are presented and the predicted performance from statistical model fitting is verified by part of a confirmation experiment. The experimental data show that the recommended factor settings substantially improved the reliability of the diamond drill bits.

Field data contain lots of information reflecting products’ field reliability under the real operating conditions. To utilize the information for reliability improvement, a framework based on field failure data is introduced. There are three steps during the procedure, including field data analysis, failure mechanism identification and reliability growth strategy. During the process of field data analysis, the main failure mode and field reliability are analyzed. Then, the physical mechanism of the failure is identified to provide a physical growth guidance. The reliability growth strategy is conducted to confirm the provided improvement guidance. Finally, a real case of the vehicle’s front hub bearing assembly is presented to illustrate its effectiveness.

Obtaining tunable photoluminescence (PL) with improved emission properties is crucial for successfully implementing fluorescent carbon nanodots (fCDs) in all practical applications such as multicolour imaging and multiplexed detection by a single excitation wavelength. In this study, we report a facile hydrothermal approach to adjust the PL peaks of fCDs from blue, green to orange by controlling the surface passivation reaction during the synthesis. This is achieved by tuning the passivating reagents in a step-by-step manner. The as-prepared fCDs with narrow size distribution show improved PL properties with different emission wavelengths. Detailed characterization of fCDs using elemental analysis, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy suggested that the surface chemical composition results in this tunable PL emission. Surface passivation significantly alters the surface status, resulting in fCDs with either stronger surface oxidation or N element doping that ultimately determine their PL properties. Further experiments suggested that the as-prepared orange luminescent fCDs (O-fCDs) were sensitive and specific nanosensing platforms towards Fe(3+) determination in a complex biological environment, emphasizing their potential practical applications in clinical and biological fields.

A multistage carrier phase estimation (CPE) scheme for any $m$ -ary quadrature amplitude modulation (QAM) formats is proposed and analyzed in coherent optical communication systems. The scheme is based on the crossed constellation transformation algorithm that is transparent to all modulation formats whose constellations are on the square grid. Simulation results show that the hardware complexity of the proposed CPE scheme can be significantly reduced by the group factors of 6.1/8.6, 4.7/6, and 2.6/3.3 (in the form of multipliers/adders) for 32-QAM, 64-QAM, and 128-QAM compared with the single-stage blind phase search algorithm. In 32-QAM, 64-QAM, and 128-QAM, coherent optical communication systems with 1-dB SNR penalty at bit error rate is $1\times 10^{-2}$ , the comparable linewidth symbol duration can be reached with the values of $6\times 10^{-5}$ , $4\times 10^{-5}$ , and $8\times 10^{-6}$ , respectively.

Low complexity carrier phase estimation (CPE) with bit-error-rate independent and modulation format transparency is very important for coherent optical communication receiver, and is still a challenge task. We propose a series of schemes of good performance and low complexity CPE, including an optical pilot-tone-added (PA) method and a crossed constellation transformation (CCT) algorithm, which are proved to be linewidth tolerant, bit-error-rate independent, modulation format transparent, and low complexity. We introduce an optical pilot-tone-added CPE scheme for a dual-carrier Nyquist m-QAM system. We also present a multi-stage CPE scheme based on CCT for either the square-frame m-QAM like 64QAM or the non-square-frame m-QAM like 32-QAM and 128-QAM.