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Background Modern industrial facilities urgently need effective wireless communication technology to monitor instruments and equipment, but electromagnetic interference and physical shielding often exist in these fields, thereby preventing traditional communication methods from working correctly. Objective As a special wireless optical communication technology, X-ray communication (XCOM) is expected to solve the problem of signal transmission under this extreme condition. Our goal was to prove the feasibility of XCOM for signal transmission under metal barrier condition. Methods The Monte Carlo method was used to simulate the transmission characteristics of X-ray beam under metal barrier conditions, and the communication performance of XCOM was evaluated. Moreover, the experimental demonstration system of XCOM was developed to test the penetration and communication performance of XCOM under metal shield. Results X-ray with energy above 150 keV could achieve a bit error rate of less than 10-4 after passing through a 20 mm iron, whereas X-ray with energy above 250 keV could maintain excellent communication performance after passing through a 30 mm iron. The experimental test results were consistent with the theoretical calculation. Conclusions As a new wireless optical communication technology, X-ray communication is expected to solve the problem of signal transmission under physical shielding conditions.

Background Growth in insect pest populations poses a significant threat to ecosystem functions and services, societal development, and food security in alpine regions under climate change. Risk assessments are important prioritization tools for pest management, which must be used to study insect pest expansion in alpine ecosystems under global warming. We used species distribution modeling to simulate the current and future distribution probabilities of 58 insect pest species in the Qinghai Province, China, based on a comprehensive field investigation. Subsequently, general linear modeling was used to explore the relationship between the distribution probability of these species and the damage caused by them. Finally, we assessed the ecological risk of insect pest expansion across different alpine ecosystems under climate change. Results Climate change could increase the distribution probabilities of insect pest species across different alpine ecosystems. However, the presence of insect pest species may not correspond to the damage occurrence in alpine ecosystems based on percent leaf loss, amount of stunting, and seedling death of their host species. Significant positive relationships between distribution probability and damage occurrence were found for several of the examined insect pest species. Insect pest expansion is likely to increase extensively in alpine ecosystems under increasing carbon dioxide (CO2 ) emission scenarios. Conclusion The relationships between distribution probability and damage occurrence should be considered in species distribution modeling for risk assessment of insect pest expansion under climate change. Our study could improve the effectiveness of risk assessment of insect pest expansion under changing climate conditions. © 2021 Society of Chemical Industry.

Enhancing the positional information acquisition during Mars entry blackout improves the Mars landing mission reliability. A positioning method based on the high-penetration of X-rays was developed to solve the problem. The X-ray signal attenuation was estimated. The positioning performance and the influence of X-ray signal transmission system were also evaluated. Results indicated that the X-ray signal attenuation is extremely low, and the X-ray-based method is expected to be a potential application for obtaining high-precision positional information during Mars entry blackout.

A three-core photonic crystal fiber (PCF) surface plasmon resonance (SPR) biosensor with high performance is presented. The structure of the biosensor is easy to implement and has good repetition. The outer layer of the fiber structure is gold film. The analyte is placed on the surface of the gold film. The Full vector finite element method is used to numerical simulation and analysis the transmission mode and characteristics of the three-core PCF-SPR biosensor. The influence of sensor structure parameters on sensing performance is investigated. The structure parameters are optimized. The optimum structure parameters are given. The refractive index (RI) sensitivity of the sensor is discussed there. The results show that the average refractive index sensitivity of the sensor is 3435 nm/RIU in the sensing range of 1.33–1.40, and the resolution is 2.91 × 10−6 RIU. The sensor has the advantages of high sensitivity and high resolution. And it can be applied to real-time detection of the biomolecules and small drug-molecules.

A D-shaped photonic crystal fiber surface plasmon resonance biosensor is presented with high sensitivity. Determinand are used outside the fiber structure to realize a simple detection mechanism. The sensor consists of photonic crystal fiber, graphene and metal. The sensitivity of the sensor is enhanced by graphene between the silver layer and D-shaped photonic crystal fiber. The two small air holes in the center of the photonic crystal fiber are beneficial to the phase matching of the core and the plasmon polaritons. The two large air holes are beneficial to the birefringence and the coupling of polarized light with metal. The Full vector finite element method is used to numerical simulation and analysis the transmission mode and characteristics of the photonic crystal fiber surface plasmon resonance biosensor. In the range of refractive index is 1.34–1.40, the average sensitivity of the sensor is 4850 nm/RIU with a high resolution of 2 × 10−5RIU. The minimum full width at half maximum is 10 nm. The proposed sensor can be applied to real-time detection of the biomolecules and small drug-molecules due to the advantages of long distance transmission, high sensitivity and high resolution.

The principle of detecting the vacuum degree of terahertz wave is discussed. The imaging principle, imaging characteristics, imaging speed, and price of pulsed terahertz and continuous wave terahertz are compared and analyzed. The conclusion shows that the pulse terahertz frequency is higher in the practicality of vacuum detection, but it is expensive, bulky and inconvenient to operate in the field. Continuous wave terahertz imaging has high frequency resolution, low price, short imaging time and practical more sexual.

Contingency plans is growing in quantity and gains higher quality in recent years. Contingency plan management has become a public service and affects our society. In this paper, we proposed a formal model of contingency plans and designed the three-layer architecture of the contingency plan management system. First, we give the formal representation of basic attributes, contents and the task model respectively. We have three layer in proposed contingency plan management system. The storage layer is designed to adapt to various types of data, such as XML and relational. The formal-model layer provides interfaces for accessing contingency plans based on formal representation. The application layer use the interfaces for different applications.

X-ray communication (XCOM) is a novel method that exploits X-rays as a carrier for data transmission. The high penetration of X-rays enables XCOM to avoid radio blackout during the atmospheric re-entry into Earth. To guarantee stable and robust XCOM, this study provides a power budget for XCOM. The Monte Carlo method was used to evaluate the transmission properties of X-ray beams in near-earth space, and a link model in the re-entry blackout region were established. Moreover, we established a noise model for the X-ray detector and evaluated the mathematical relationship between the transmitting power, and the bit-error-rate (BER). Results indicated that the X-rays with energies of 30–50 keV are highly suitable at an altitude of 35 km, and that robust communication performance could be obtained by using soft X-rays in the upper atmosphere. Adopting optimal X-ray energies according to different altitudes of spacecraft re-entry is, thus, of great significance. We calculated the minimum transmitting power of the X-ray source for a targeted BER and found that, when the link distance is 295 km and the X-ray energy is 50 keV, the power consumption of the X-ray source must be 140 W to achieve BER of less than 10−6 level.

Due to the emergency plan format information characteristics is stronger and more easily to gain the complete content description, so this paper puts forward the recommendation algorithm of emergency plan based on content filtering. This paper proposes the characteristics model of emergency plan and the user's interest model and designs the flexible recommendation interface for user interactive, so we can get the recommend results.

How to ensure a smooth, fast and efficient emergency response procedure becomes a highly concerned issue. However, a procedure of emergency plan may be confusing and inefficient in reality due to delay caused by waiting for decision-making, responding to conflicts and limited resource during the process of dealing with emergency. In this paper, we propose a colored stochastic Petri net to evaluate the security and complexity of emergency response procedure and the reasonableness of resource flow, so as to effectively analyze the potential deficiencies of emergency response procedure. We firstly establish a colored stochastic Petri net, and then convert the colored stochastic Petri net to an isomorphic Markov chain. Studying the structural properties of the colored stochastic Petri net and steady-state nature of the Markov chainprovides a scientific basis for the perfection of emergency plan. Meanwhile, it also ensures an ordered and efficient implementation of emergency response procedure in an emergency.

For vibration control of long-span arch bridges under multi-support seismic excitation, this paper presents schemes of control to seismic responses of arch bridges with Magneto-Rheological dampers(MRD). In the semi-active control system of arch bridge-MRD, Linear Quadratic Gaussian (LQG)-based Sign function control algorithm is used to command MRD，and traveling wave effects on the responses of structure are considered. The Nimu arch bridge is used as a simulation example to verify the proposed control scheme. Numerical results show that traveling wave effects have no unfavorable influence on the control to response of arch bridge.

A new sensor — transverse electric (TE) polarized excite surface plasmon resonance (SPR) fiber optic biosensor is proposed. The graphene is the plasma layer. The transfer matrix method and the finite difference time domain method are applied to conduct the numerical simulation of the four layers (fiber core/photonic crystals/graphene/sample) of fiber optic biosensor. The results show that the relationship between refractive index and resonant wavelength is linear and the sensitivity of the fiber optic biosensor reaches 1942 nm/RIU.

Recent advances in wireless mobile computing, digital library, and distributed multimedia technologies are stimulating the development of mobile multimedia digital library systems (M2DLS) that allow mobile clients to access multimedia material anywhere and anytime over a cellular radio network. This paper addresses the problem of providing synchronized multimedia retrieval in these systems. An efficient inter-media synchronization scheme called wireless prioritized feedback (WPF) for mobile multimedia on-demand retrieval in digital library systems over CDMA cellular radio networks in the absence of synchronized clocks is presented. In the WPF scheme, base stations use preferential lightweight message called feedback units transmitted by mobile mediaphones to detect and correct asynchronies. The algorithm is described with pseudo code, and experiments are described to demonstrate the efficiency of WPF.

An optical fiber surface plasmon resonance biosensor is presented that allows to numerically demonstrate, using transfer matrix method and the finite difference time domain method, the detection range is very wide. Two different structures of graphene photonic crystal multilayer (i.e. sensor I and sensor II) are constructed in the cladding region of single-mode fiber. Graphene is used as the plasma layer instead of the traditional metal. According to the analysis, the properties of graphene can be changed by adjusting the chemical potential µ c . In the spectral region of 1.667| µ c | ћω µ c |, the imaginary part of conductivity σ ″ becomes negative. Thus the weakly bounded low-less TE-SPR is supported by graphene. The results of the numerical simulation show that the relationship between refractive index and resonant wavelength is linear. The sensor I can detect the refractive index range of 1.33–1.4, and the sensitivity is 1942 nm/RIU. The sensor II can detect the refractive index range of 1.41–1.67, and the sensitivity is up to 2315.4 nm/RIU. Therefore, the detection of wide refractive index range of 1.33–1.67 or simultaneous detection of different biological medium concentration is realized by the sensor.

Simultaneous organic carbon and nitrogen removal was studied in a sequencing batch reactor (SBR) fed with synthetic municipal wastewater and controlled at a low dissolved oxygen (DO) level (0.8 mg dm−3). Experimental results over a long time (120 days) showed that the reactor achieved high treatment capacities (organic and nitrogen loading rates reached as high as 2.4 kg COD m−3 d−1 and 0.24 kg NH3-N m3 d−1) and efficiencies (COD, NH3-N and total nitrogen removal efficiencies were 95%, 99% and 75%). No filamentous bacteria were found in the sludge even though the reactor had been seeded with filamentous bulking sludge. Instead, granular sludge, which possessed high activity and good settleability, was formed. Furthermore, the sludge production rate under low DO was less than that under high DO. Significant benefits, such as low investment and less operating cost, will be obtained from the new process. © 2001 Society of Chemical Industry