Analyze the FMCW Waveform Skin Return of Moving Objects in the Presence of Stationary Hidden Objects Using Numerical Models

In this paper, a high-performance antenna array system model is presented to analyze moving-object-skin-returns and track them in the presence of stationary objects using frequency modulated continuous wave (FMCW). The main features of the paper are bonding the aspects of antenna array and electromagnetic (EM) wave multi-skin-return modeling and simulation (M&S) with the aspects of algorithm and measurement/tracking system architecture. The M&S aspect models both phase and amplitude of the signal waveform from a transmitter to the signal processing in a receiver. In the algorithm aspect, a novel scheme for FMCW signal processing is introduced by combining time- and frequency-domain methods, including a vector moving target indication filter and a vector direct current canceller in time-domain, and a constant false alarm rate detector and a mono-pulse digital beamforming angle tracker in frequency-domain. In addition, unlike previous designs of using M × N fast Fourier transform (FFT) for an M × N array, only four FFTs are used, which tremendously save time and space in hardware. With the presented model, the detection of the moving-target-skin-return in stationary objects under a noisy environment is feasible. Therefore, to track long range and high-speed objects, the proposed technique is promising. Using a scenario having (1) a target with 17 dBm2 radar cross section (RCS) at about 40 km range with 5.936 Mach speed and 11.6 dB post processing signal to noise ratio, and (2) a strong stationary clutter with 37 dBm2 RCS located at the proximity of the target, it demonstrates that the root-mean-square errors of range, angle, and Doppler measurements are about 26 m, 0.68 degree, and 1100 Hz, respectively

Accumulatively Increasing Sensitivity of Ultrawide Instantaneous Bandwidth Digital Receiver with Fine Time and Frequency Resolution for Weak Signal Detection

It is always an interesting research topic for digital receiver (DRX) designers to develop a DRX with (1) ultrawide instantaneous bandwidth (IBW), (2) high sensitivity, (3) fine time-of-arrival-measurement resolution (TMR), and (4) fine frequency-measurement resolution (FMR) for weak signal detection. This is because designers always want their receivers to have the widest possible IBW to detect far away and/or weak signals. As the analog-to-digital converter (ADC) rate increasing, the modern DRX IBW increases continuously. To improve the signal detection based on blocking FFT (BFFT) method, this paper introduces the new concept of accumulatively increasing receiver sensitivity (AIRS) for DRX design. In AIRS, a very large number of frequency-bins can be used for a given IBW in the time-to-frequency transform (TTFT), and the DRX sensitivity is cumulatively increased, when more samples are available from high-speed ADC. Unlike traditional FFT-based TTFT, the AIRS can have both fine TMR and fine FMR simultaneously. It also inherits all the merits of the BFFT, which can be implemented in an embedded system. This study shows that AIRS-based DRX is more efficient than normal FFT-based DRX in terms of using time-domain samples. For example, with a probability of false alarm rate of 10−7, for N=220 frequency-bins with TMR = 50 nSec, FMR = 2.4414 KHz, IBW > 1 GHz and ADC rate at 2.56 GHz, AIRS-based DRX detects narrow-band signals at about −42 dB of input signal-to-noise ratio (Input-SNR), and just uses a little less than N/2 real-samples. However, FFT-based DRX have to use all N samples. Simulation results also show that AIRS-based DRX can detect frequency-modulated continuous wave signals with ±0.1, ±1, ±10 and ±100 MHz bandwidths at about −39.4, −35.1, −30.2, and −25.5 dB of Input-SNR using about 264.6 K, 104.7 K, 40.2 K and 18.3 K real-samples, respectively, in 220 frequency-bins for TTFT

Environmental Penalties, Investor Attention and Stock Market Reaction: Moderating Roles of Air Pollution and Industry Saliency

Despite the importance of environmental penalties in environmental enforcement, how and under what situations they impact stock market reaction is still unclear. Drawing on the theories of expectancy violation and attention driven, a conceptual model is built to explore how environmental penalty influences stock market reaction through investor attention. Furthermore, it is explored that the air pollution and industry saliency facilitate the indirect relationship between environmental penalty and investor attention. We empirically test this theoretical framework using a sample of 88 listed companies that received the environmental penalty. Up to 31 December 2020, a total of 88 A-share listed companies in Shanghai and Shenzhen stock exchanges were obtained as samples by collecting the announcement of environmental penalties of listed companies on Juchao Network. Furthermore Baidu index is taken as a proxy for investor attention in this study. Our findings reveal that investor attention plays mediating role in the relationship between environmental penalty and abnormal returns, while the direct effect of environmental penalty on stock market reaction has not been verified, thus, investor attention plays a complete mediating role between them. In addition, air pollution moderates the relationship between Environmental penalties and investor attention. The study found that enterprises in heavy pollution industries might suffer safety-in-numbers effect, which would weaken the directly negative impact of environmental penalties, and verified the moderating effect of industry saliency. These findings provide theoretical and practical implications for understanding how environmental penalties influence on stock market reaction

Responses to shade and subsequent recovery of soya bean in maize-soya bean relay strip intercropping

In relay intercropping systems, late-planted crops often grow under the shade of the canopy of early-planted tall crops and then transfer to full sunlight after the harvest of the early-planted crops. In order to know the effects of recovery growth of the late-planted soya bean in maize–soya bean relay intercropping, a field experiment was carried out to observe architectural, morphological, physiological and anatomical traits of soya bean plants related to shade and subsequent removal in intercropping before and after maize harvest, respectively. During shade period, soya bean biomass was severely reduced, and stem elongation was stimulated. Typical features of shade grown leaves were found, such as lower LMA (leaf mass per unit area), thinner thickness, higher chlorophyll content, lower chlorophyll a:b ratio. Whole-plant leaf area analysis found that soya bean increased leaf area ratio by adjusting leaf morphology rather than by dry mass allocation. After maize harvest, leaf area and leaf mass increased rapidly, contributing to compensation growth in intercropped soya bean. Meanwhile, physiological and anatomical traits of leaf went back to similar levels as grown in sole cropping. However, stem morphological traits were irreversible after removal of shade. Finally, no difference on seed weight per plant of soya bean was observed between relay intercropping and sole cropping. Based on these findings, we speculated the recovery growth might be the direct determining factor on pod formation in soya bean, and improvement on the capacity of recovery growth could increase yield of relay intercropped soya bean

Additional file 1: Table S1. of Factors associated with spontaneous abortion: a cross-sectional study of Chinese populations

The odds ratio of spontaneous abortion associated different socioeconomic status, by urban. (DOCX 14 kb

Additional file 2: Table S2. of Factors associated with spontaneous abortion: a cross-sectional study of Chinese populations

The odds ratio of spontaneous abortion associated different socioeconomic status, by rural. (DOCX 14 kb

The relationships of school-based sexuality education, sexual knowledge and sexual behaviors—a study of 18,000 Chinese college students

Abstract Background A growing prevalence of unexpected pregnancies and younger age of sexual debut is observed among Chinese young people, while they lack formal sexuality education from schools and parents. It is necessary to measure their knowledge level of sexual and reproductive health, and how such knowledge associates with their sexual behaviors and reproductive health outcomes, which would shed light on the effectiveness of sexuality education in China. Methods An Internet-based questionnaire survey was conducted from January to August, 2015. 130 colleges were selected from eastern, central, and western parts China with a good balance of geographic distributions. The survey link was subsequently delivered to the focal points in each college for voluntary participation, targeting on undergraduates aged 18 ~ 25. Information on demographics, experience of school-based sexuality education (defined as any course introducing information on sexual and reproductive health) and SRH knowledge quiz was collected. Multivariate linear regression and logistic regression were applied to explore the relationship between students’ SRH knowledge, sexual behaviors and reproductive health outcomes, such as sexual intercourse (penetrative sex by vaginal or anal), unprotected sex, pregnancy and abortion, etc. Results A total sample of 17,966 Chinese college students (mean age = 20.2, 60.4% female) eventually entered the analysis. Only 55.6% of the respondents self-reported having received sexuality education before, and they scored significantly higher (2.33/4.00) in the SRH knowledge quiz than those who had not (1.75/4.00). Among the sexually experienced students (n = 3639, 20.2%), both males and females with higher SRH knowledge were less likely to report having experience of (partner’s) pregnancy or abortion (OR < 1, p < 0.05). In the group of sexually experienced males, those with higher SRH knowledge had a slightly later age of sexual debut (coefficient = 0.28, p < 0.001), and were less likely to have unprotected sex during the last or in most sexual intercourses (OR = 0.82, 95%C.I.: 0.69 ~ 0.96). Conclusion Students’ experience of school-based sexuality education may be positively associated with their SRH knowledge level as well as with their sexual behaviors and reproductive health outcomes, but such associations were stronger among males than females. A more effective implementation of school-based sexuality education needs to be scaled up, and a gender-sensitive education strategy to different needs is desirable for SRH promotion among Chinese young people

Blue-Light-Dependent Stomatal Density and Specific Leaf Weight Coordinate to Promote Gas Exchange of Soybean Leaves

Blue and red light are essential light signals used to regulate stomatal development and leaf structure. In the present study, stomatal and leaf traits that respond to blue and red light were studied at two light intensities (400 and 100 µmol m−2 s−1) in soybeans. The stomatal traits and leaf characteristics were determined. Furthermore, their contribution to the operational maximum stomatal conductance (gopmax) was evaluated using the rdacca.hp R package. With the light intensity significantly reduced, the stomatal size (SZ) under blue light did not change. Similarly, the decrease in light intensity did not influence the stomatal density (SD), specific leaf weight (SLW) or gopmax under red light. These results implied that the regulation of SD and SLW depended on blue light and that SZ was highly sensitive to red light. In addition, SLW was strongly correlated with SD. The SLW and SD had the highest contribution rates (19.43% and 19.5%, respectively) to gopmax, as compared with the other parameters. In conclusion, these results suggested that in long-term exposure to blue light, the enhancements in gopmax were primarily due to the synergistic promotion of SLW and SD

Effect of narrow-row planting patterns on crop competitive and economic advantage in maize–soybean relay strip intercropping system

Narrow-row planting patterns directly affect crop yield and competition in intercropping systems. A two-year (2012 and 2013) field experiment was conducted to determine the interactive behavior between intercrops in a maize–soybean relay strip intercropping system. Maize plants were planted in different narrow-wide row planting patterns, whereas soybean was planted in wide rows. The total biomass and grain yield of maize increased with increasing maize narrow-row spacing, but the opposite trend was observed for soybean. The aggressivity, competitive ratio, and partial relative crowding advantage values for maize were greater than those for soybean. Moreover, the competitive interaction of the intercrops was affected by the distance between maize and soybean rows. The highest intercrop land equivalent ratio (LER) 1.61 and 1.59 was found in the 40:160 planting pattern (i.e. 40 cm narrow-row spacing and 160 cm wide-row spacing of maize) during 2012 and 2013, respectively. Combined with actual yield loss and LER, the intense intra-specific competition of maize plants reduced the depression for the associated soybeans when the maize narrow-row spacing was less than 30 cm. When the narrow-row spacing was wider than 50 cm, soybean growth was seriously depressed by maize because of the stronger inter-specific competition between maize and soybean. The maximum yield and economic advantage appeared in the 40:160 narrow-wide row planting pattern. Therefore, intercropping advantage may be achieved by changing the row spacing and distance between intercrop rows to coordinate the inter-specific competition between maize and soybean