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The rock mass consists of rock blocks and structural planes, which can reduce its integrity and strength. Therefore, accurately obtaining the characteristics of the rock mass structural plane is a prerequisite for evaluating stability and designing supports in underground engineering. Currently, there are no effective testing methods for the characteristic parameters of the rock mass structural plane in underground engineering. The paper presents the digital drilling technology as a new testing method of rock mass structural planes. Flawed rock specimens with cracks of varying widths and angles were used to simulate the rock mass structural planes, and the multifunctional rock mass digital drilling test system was employed to carry out the digital drilling tests. The analysis focuses on the variation laws of drilling parameters, such as drilling pressure and drilling torque, affected by the characteristics of prefabricated cracks, and clarifies the degradation mechanism of rock equivalent compressive strength. Additionally, an identification model for the characteristic parameters of rock mass structural planes during drilling is established. The test results indicate that the average difference of the characteristics of prefabricated cracks identified by the equivalent compressive strength is 2.45° and 0.82 mm, respectively. The identification model while drilling is verified to be correct due to the high identification accuracy. Based on this, a method for testing the characteristic parameters of the surrounding rock structural plane while drilling is proposed. The research offers a theoretical and methodological foundation for precise in situ identification of structural planes of the surrounding rock in underground engineering.

Intervertebral disc degeneration (IDD) serves as the underlying pathology for various spinal degenerative conditions and is a primary contributor to low back pain (LBP). Recent studies have revealed a strong correlation between IDD and biological processes such as Programmed Cell Death (PCD), cellular senescence, inflammation, cell proliferation, extracellular matrix (ECM) degradation, and oxidative stress (OS). Of particular interest is the emerging evidence highlighting the significant involvement of the JNK signaling pathway in these fundamental biological processes of IDD. This paper explores the potential mechanisms through the JNK signaling pathway influences IDD in diverse ways. The objective of this article is to offer a fresh perspective and methodology for in-depth investigation into the pathogenesis of IDD by thoroughly examining the interplay between the JNK signaling pathway and IDD. Moreover, this paper summarizes the drugs and natural compounds that alleviate the progression of IDD by regulating the JNK signaling pathway. This paper aims to identify potential therapeutic targets and strategies for IDD treatment, providing valuable insights for clinical application.

Rapid urbanization in mountainous areas has caused unbalanced development, land use conflicts, and decreased urban spatial efficiency (USE) due to terrain constraints and disorderly land expansion, and this issue has not been fully explored. To address this gap, this study constructs a framework to quantify the impacts of landscape gradients on urban spatial efficiency. By developing indicator systems to characterize both landscape heterogeneity and urban spatial efficiency, the relationships between these factors are analyzed using the Boosting Regression Trees model, and clusters are identified to reveal spatial differentiation through key landscape gradient indicators. The results indicate that (1) the Summit Density (Sds) of Normalized Difference Vegetation Index (NDVI) exhibits the most significant negative impact on urban spatial efficiency, especially on spatial utilization efficiency; (2) the Root Mean Square Slope (Sdq) of Digital Elevation negatively affects traffic and public services efficiency; (3) the Texture Direction Index (Stdi) of building distribution has the most significant positive impact on public service efficiency. In mountainous environments, different landscape gradient types exhibit clear contrasts in urban spatial efficiency. Varied elevations lead to diverse construction sites and building layouts within urban blocks, resulting in spatial differentiation of urban spatial efficiency. This study enhances the use of gradient surface metrics in urban spatial research by describing landscape patterns and heterogeneity at the block scale. It offers valuable insights for urban planning and design with a focus on equity and sustainability.

Existing methods for constructing Landscape Ecological Networks (LEN) either focus on functional attributes or structural attributes and also do not address the dynamic impact of urban development on ecological spaces. To address these limitations, this paper proposed evaluating the maximum connectivity (k) of potential LEN, composed of existing ecological spaces, using a network fault tolerance index. We then used graph-based networking technology to construct the optimal LEN structure based on this index. Specifically speaking, first, we identified the existing LEN with the highest ecosystem service capacity and lowest ecological cost in the study area. Using four landscape pattern metrics, we comprehensively evaluated the fault tolerance index as the maximum connectivity k of potential LEN and determined that k = 7. We then modeled the existing LEN as a weighted graph and transformed the network optimization problem into a k-edge addition problem. This calculation yielded seven LEN schemes, each corresponding to different priority orders of new ecological corridors based on k value. This index captures changes in ecological space patterns and offers diverse LEN optimization solutions. It provides practitioners with flexible spatial strategies to address the dynamic impacts of urbanization.

Abstract Random bit generators are critical for information security, cryptography, stochastic modeling, and simulations. Speed and scalability are key challenges faced by current physical random bit generation. Herein, we propose a massively parallel scheme for ultrafast random bit generation towards rates of order 100 terabit per second based on a single micro-ring resonator. A modulation-instability-driven chaotic comb in a micro-ring resonator enables the simultaneous generation of hundreds of independent and unbiased random bit streams. A proof-of-concept experiment demonstrates that using our method, random bit streams beyond 2 terabit per second can be successfully generated with only 7 comb lines. This bit rate can be easily enhanced by further increasing the number of comb lines used. Our approach provides a chip-scale solution to random bit generation for secure communication and high-performance computation, and offers superhigh speed and large scalability.

Common-signal-induced synchronization of semiconductor lasers with optical feedback inspired a promising physical-layer key distribution with information-theoretic security and potential in high rate. A significant challenge is the requirement to shorten the synchronization recovery time for increasing the key rate without sacrificing the operation parameter space for security. Here, open-loop synchronization of wavelength-tunable multi-section distributed Bragg reflector lasers is proposed as a solution for physical-layer key distribution. Experiments show that the synchronization is sensitive to two operation parameters, i.e., currents of grating section and phase section. Furthermore, fast wavelength-shift keying synchronization can be achieved by direct modulation on one of the two currents. The synchronization recovery time is shortened by one order of magnitude compared to close-loop synchronization. An experimental implementation is demonstrated with a final key rate of 5.98 Mbit/s over 160 km optical fiber distance. It is thus believed that fast-tunable multi-section semiconductor lasers open a new avenue for a high-rate physical-layer key distribution using laser synchronization.

Urban green spaces play a crucial role in enhancing the quality of life by providing ecological, social, and economic benefits [...]

Changes in land cover by rapid urbanization have diminished the cooling effect of urban green spaces (UGS), exacerbating the upward trend of land surface temperature (LST). A thorough and precise understanding of the spatio-temporal characteristics of UGS and LST is essential for mitigating localized high temperatures in cities. This study identified the spatio-temporal changes in UGS configuration and LST in Shanghai from 2003 to 2022. The correlation between UGS configuration and LST was explored using spatial autocorrelation analysis and causal inference. The results show that (1) the high-temperature space had grown from 721 km2 in 2003 to 3059 km2 in 2022; (2) in suburbs, the largest area of UGS tended to decrease, while the number of patches tended to increase, indicating a distinct feature of suburbanization; (3) changes in the largest area of UGS had more significant spatial correlation, indicating that urban sprawl primarily impacts large UGSs; and (4) compared to the number and shape of UGS, changes in the largest area are the key factor influencing regional LST. These findings enrich the knowledge of the spatio−temporal relationship between the UGS configuration and its cooling effect in urbanization, offering valuable insights for building cooler cities.

Mapping cultural ecosystem services (CES) in river basins is crucial for spatially identifying areas that merit conservation due to their significant CES contributions. However, precise quantification of the appropriate area of mapping units, which is the basis for CES assessment, is rare in existing studies. In this study, the optimal area threshold of mapping units (OATMU) identification, consisting of a multi-dimensional indicator framework and a methodology for validation, was established to clarify the boundary and the appropriate area of the mapping units for CES. The multi-dimensional indicator framework included geo-hydrological indicator (GI), economic indicator (EI) and social management indicator (SMI). The OATMU for each indicator was determined by seeking the inflection point in the second-order derivative of the power function. The minimum value of the OATMU for each indicator was obtained as the OATMU for CES. Finally, the OATMU for CES was validated by comparing it with the area of administrative villages in the river basin. The results showed the OATMU for CES was 3.60 km2. This study adopted OATMU identification, with easy access to basic data and simplified calculation methods, to provide clear and generic technical support for optimizing CES mapping.

We propose and experimentally demonstrate a wireless-channel key distribution scheme based on laser synchronization induced by a common wireless random signal. Two semiconductor lasers are synchronized under injection of the drive signal after electrical-optical conversion and emit irregular outputs that are used to generate shared keys. Our proof-of-concept experiment using a complex drive signal achieved a secure key generation rate of up to 150 Mbit/s with a bit error rate below 3.8 × 10−3. Numerical simulation results show that the proposed scheme has the potential to achieve a distribution distance of several hundred meters. It is believed that common-signal-induced laser synchronization paves the way for high-speed wireless physical-layer key distribution.

In this article, we propose and numerically demonstrate a novel dual-phase modulated time-delay signature (TDS) concealed communication system. The proposed system addresses the fatal disadvantage of conventional electro-optic chaotic systems in that TDS is vulnerable to detection. Combined with the dispersive devices ahead, which significantly expands the complexity of the signal, the scheme perturbs the transmitted data with the mutual injection of the feedforward and feedback branches in the phase, strengthening the nonlinear effect of the system considerably. In addition, the key space of the system against illegal users’ exhaustive attack within reasonable parameters reaches 1019, which is 14 orders of magnitude larger than that of the classical electro-optic system. A confidential 32 G/s OOK signal was transmitted over 100 km and successfully recovered. Numerical results demonstrate that the chaotic system can tolerate minor parameter mismatches which are controllable in practice, proving that the system can be used for secure communication.

In this paper, a novel phase encryption scheme based on a dual-loop electro-optic self-feedback structure is proposed for time-delay signature (TDS) concealment. As for a conventional single-loop feedback structure, the TDS is extremely vulnerable to exposure in the common link, resulting in a fatal weakness in the entire security system, whereas, the introduction of an additional feedback branch, brings about the mutual dynamics between the phase feedbacks, and effectively solves the problem. The modulation depth and dispersion values, which are two crucial variables affecting TDS concealment, are investigated in detail. In principle, the scheme is verified to have better robustness, more security, and can supply large key space. Error-free transmission of high-speed signals is possible. Thanks to the aforementioned benefits, the dual-loop electro-optic structure proposed could inspire fresh ideas for secure optical communication systems in the future.

As an inherent part of the landscape ecological network (LEN), the ecological corridor is the bridge between ecological sources and also the key to ensuring urban ecological security. Existing studies on ecological corridors mostly stay in the large scale of landscape patterns and lack guidance for corridor structure design or optimization at the land use level. To provide a reference for the internal landscape structure adjustment of the ecological corridor composed of hybrid land use in the rapidly urbanized areas, first, we constructed the “Comprehensive benefit index of ecological corridors I” by using the three indexes of “Ecological benefit enhancement potential”, “Economic input cost” and “Social coordination cost”. Second, with the goal of maximizing the comprehensive benefits of the three aspects of ecological corridor construction, we established a functional relationship between the converted agricultural land area A, constructed land area C, and index I to determine the optimal proportion of agricultural lands and constructed lands converted into ecological lands within the planning scope of the ecological corridors. The results show that (1) according to the conversion ratio, the ecological corridors in the study area can be divided into three degrees of conversion rate: low, moderate, and high. (2) Among the 66 ecological corridors, the agricultural lands in 26 ecological corridors and the constructed lands in 35 ecological corridors need to be converted into ecological land at a high ratio to ensure the comprehensive benefits of the corresponding corridors. We also put forward suggestions for landscape structure adjustment and optimization for ecological corridors with different conversion degrees. This method can help balance the benefits of different stakeholders in the city and implement the results of ecological corridor planning on a large spatial and temporal scale at the land use level.

Rapid global urbanization has caused habitat degradation and fragmentation, resulting in biodiversity loss and the homogenization of urban species. Birds play a crucial role as biodiversity indicators in urban environments, providing multiple ecosystem services and demonstrating sensitivity to changes in habitat. However, construction activities often disrupt urban bird habitats, leading to a decline in habitat quality. This paper proposes a framework for prioritizing habitat restoration by pinpointing bird hotspots that demand attention and considering the matching relationship between bird richness and habitat quality. Shanghai represents a typical example of the high-density megacities in China, posing a significant challenge for biodiversity conservation efforts. Utilizing the random forest (RF) model, bird richness patterns in central Shanghai were mapped, and bird hotspots were identified by calculating local spatial autocorrelation indices. From this, the habitat quality of hotspot areas was evaluated, and the restoration priority of bird habitats was determined by matching bird richness with habitat quality through z-score standardization. The results were as follows: (1) Outer-ring green spaces, large urban parks, and green areas along coasts or rivers were found to be the most important habitats for bird richness. Notably, forests emerged as a crucial habitat, with approximately 50.68% of the forested areas identified as hotspots. (2) Four habitat restoration types were identified. The high-bird-richness–low-habitat-quality area (HBR-LHQ), mainly consisting of grassland and urban construction land, was identified as a key priority for restoration due to its vulnerability to human activities. (3) The Landscape Shannon’s Diversity Index (SHDI) and Normalized Difference Vegetation Index (NDVI) are considered the most significant factors influencing the bird distribution. Our findings provide a scientifically effective framework for identifying habitat restoration priorities in high-density urban areas.

Chaotic optical communication based on conventional external cavity semiconductor laser is a very promising solution for physical layer secure communication. However, the intrinsic time delay signature (TDS) associated with the external cavity length and the potential direct linear filtering (DLF) or synchronization utilization attack greatly threaten the system security. In this work, we propose and numerically demonstrate a novel scheme for TDS suppression and security enhancement of chaotic optical communication based on external temporal self-feedback hardware encryption and decryption. In this scheme, the confidential chaotic modulated signal is temporally scrambled in the time domain by two optical dispersion components and an electro-optic self-feedback phase modulation loop between them, which simultaneously conceal the TDS and enhance the security against malicious attacks. Proof-of-principle demonstration for a security enhanced chaotic optical communication system with error free transmission is successfully achieved. The proposed scheme may provide a promising way for pure-hardware based physical secure chaotic optical communication systems.

The cooling effect of green infrastructure (GI) is becoming a hot topic on mitigating the urban heat island (UHI) effect. Alterations to the green space are a viable solution for reducing land surface temperature (LST), yet few studies provide specific guidance for landscape planning adapted to the different regions. This paper proposed and defined the landscape complexity and the threshold value of cooling effect (TVoE). Results find that: (1) GI provides a better cooling effect in the densely built-up area than the green belt; (2) GI with a simple form, aggregated configuration, and low patch density had a better cooling intensity; (3) In the densely built-up area, TVoE of the forest area is 4.5 ha, while in the green belt, TVoE of the forest and grassland area is 9 ha and 2.25 ha. These conclusions will help the planners to reduce LST effectively, and employ environmentally sustainable planning.

Two parameter-matched Fabry-Perot lasers injected by a super-luminescent diode, after independent and random mode selection, emit chaotic lights with synchronization on-off keying. Shared keys are extracted from the synchronous waveforms.

Terahertz (THz) noise sources play an irreplaceable role in testing THz devices and evaluating THz application systems, and the flatness of their radio frequency (RF) spectra is an important technical parameter. In this paper, a scheme for generating flat THz noise by mixing multiple filtered incoherent light fields is proposed. A theoretical analysis is conducted to investigate the impact of different spectral linewidths and central wavelength differences of incoherent light fields on the noise power and RF spectrum flatness, and an optimized experimental scheme is obtained. The results show that the proposed method can generate a 280–380 GHz flat THz noise signal with an RF spectrum flatness of ±0.5 dB in simulation and ±2.7 dB in our experiments. This article provides an excellent technical solution to the demand for flat THz noise in the THz field.

Submarine optical cables, utilized as fiber-optic sensors for seismic monitoring, are gaining increasing interest because of their advantages of extending the detection coverage, improving the detection quality, and enhancing long-term stability. The fiber-optic seismic monitoring sensors are mainly composed of the optical interferometer, fiber Bragg grating, optical polarimeter, and distributed acoustic sensing, respectively. This paper reviews the principles of the four optical seismic sensors, as well as their applications of submarine seismology over submarine optical cables. The advantages and disadvantages are discussed, and the current technical requirements are concluded, respectively. This review can provide a reference for studying submarine cable-based seismic monitoring.

Optimizing the configuration of green–blue spaces is crucial in mitigating the urban heat island effect. However, many existing studies neglect to consider the synergistic cooling effect of green–blue space and its spatial comparison, focusing instead on individual ecological elements of green space or water bodies. Additionally, the relative importance of different configuration indicators and their marginal effects on the cooling effect of green–blue space remain unclear, with an identified need for the quantification of indicator thresholds for maximizing the cooling effect. To address these gaps, this study investigated green–blue spaces in 30 urban waterfront communities located in Kunshan City, Jiangsu Province, China, and measured the scale, distribution, morphology, green–blue relationship, and built environment of these spaces. To determine the cooling effect, maximum air temperature and mean cold island intensity were measured using ENVI-met simulations. Correlation analyses and boosted regression trees (BRT) were utilized to identify the configuration indicators that affect the cooling effect and their action threshold. The results show that green space distribution and water body shape are the most important features affecting the maximum air temperature, with green space patch density (PD) and water landscape shape index (LSI) contributing 21.3% and 20.9% to the reduction in temperature, while the thresholds are 550 and 4.2, respectively. The contribution of green–blue space percentage is critical in raising urban cold island intensity, with threshold effects at 43%. These findings provide practical guidance for the efficient exploitation of the synergistic cooling effects of green–blue space and enhancement of climate resilience in coastal cities.

Self-accelerating beams have the unusual ability to remain diffraction-free while undergo the transverse shift during the free-space propagation. We theoretically identify that the transverse optical field distribution of 2D self-accelerating beam is determined by the selection of the transverse Cartesian coordinates, when the caustic method is utilized for its trajectory design. Based on the coordinate-rotation method, we experimentally demonstrate a scheme to flexibly manipulate the rotation of transverse optical field for 2D self-accelerating beams under the condition of a designated trajectory. With this scheme, the transverse optical field can be rotated within a range of 90 degrees, especially when the trajectory of 2D self-accelerating beams needs to be maintained for free-space photonic interconnection.

Global urbanization and post-industrialization have resulted in the emergence of a large number of brownfields. The integration of brownfields into green infrastructure (GI) has been widely recognized as a sustainable development strategy in metropolitan areas. It is important to spatially prioritize brownfields catering for GI, which can enable the greatest enhancement of urban functions. Various studies have assessed brownfield site attributes or urban demands to define the priority of brownfields transformed into GI, but it is key to consider the coupling coordination between urban demands and site attributes in order to achieve more accurate matches. In this paper, an approach is proposed for assessing the priority of brownfields catering for GI in Xuzhou, China; this involved calculating the coupling coordination degree between site attributes and urban function demands, including heat island mediation, stormwater regulation, disaster prevention, landscape aesthetics improvement, and leisure and recreation increments. The results showed that 42.52% of the brownfields have a high degree of coupling coordination (“good coordination” and “primary coordination”) between site attributes and urban demands. Furthermore, 40.82% of the brownfields (120 plots) were selected to be integrated into urban GI; these are not only located in high urban functional demand areas, but also have a high coupling coordination degree. These brownfields were divided into three priority levels, and 4.42% and 17.69% of the total brownfields are of very high and high priority. Our proposed approach offers an accurate decision-making tool for urban GI optimization in high-density built-up metropolitan areas, and offers guidance for brownfield redevelopment.

In this paper, we propose a method for cracking the key parameters of an electro-optic self-feedback temporal optical phase encryption system and experimentally demonstrate the feasibility of the scheme. By scanning a tunable dispersion compensation (TDC) module at the receiver, the time delay signature (TDS) of an encrypted signal can be exposed, making it possible to extract other key parameters of the system and reconstruct a decryption setup. The TDS characteristics for three typical modulation formats are investigated, revealing that while such an encryption system is secure against power detection attack, there is a risk of TDS leakage. The findings can guide the design of advanced optical encryption schemes with TDS suppression for security enhancement.

We propose a scheme for key-space-enhanced chaos secure communication using semiconductor lasers with spectrum-programmable optoelectronic feedback. This feedback consists of multiple parallel optoelectronic feedback loops composed of bandpass filters and radio-frequency amplifiers. The centre frequencies of the filters and gain coefficients of the amplifiers increase the key space. We use 12 parallel filtered feedback loops to analyse the effects of parameter mismatch on the synchronization quality. The simulation result indicates that the key space reaches approximately 2100 at a data rate of 10 Gbit/s, and it can be further enhanced by increasing the number of feedback loops. These results suggest an alternative approach for security-enhanced optical chaos communication.

Chaotic secure communication schemes encounter a conflict of key space enhancement between the consistency and complexity of chaotic transceivers. In this paper, we propose a monolithically integrated multi-section semiconductor laser (MIMSL), used as a compact chaotic transceiver with an enhanced key space. The MIMSL consists of a distributed feedback (DFB) laser section, a semiconductor optical amplifier (SOA) section, two phase (P) sections and a passive optical waveguide. We simulate the dynamics of the MIMSL by applying the time-dependent coupled-wave equations for traveling-wave optical fields. Further, we numerically demonstrate a security enhancement of the unidirectional chaotic communication scheme using the MIMSL transceivers with independent high-speed modulation in the phase sections of the MIMSL. The security of our scheme depends not only on the difficulty of identifying the MIMSL structural parameters and the bias current of each section, but also on the phase shifts in two phase sections providing the additional dimension of security key space. Final simulation results show that a total of 248 key spaces can be achieved with a data rate of 2.5 Gb/s and an injection strength of 0.36.

We propose a simple method to generate broadband polarization chaos using two mutually coupled free-running vertical-cavity surface-emitting lasers (VCSELs). Specifically, we quantitatively investigate the effect of critical external parameters (bias current, frequency detuning and coupling coefficient) on the polarization chaos bandwidth in the scenarios of parallel injection and orthogonal injection, and reveal the physical mechanism of bandwidth enhancement in two scenarios. Final simulation results show that the bandwidth of chaotic signals obtained from parallel and orthogonal injection can reach 35.15 GHz and 32.96 GHz, respectively.

We propose and numerically demonstrate the generation of wideband millimeter-wave (mmW) flat chaos with controllable power spectrum by injection of chaotic signal from external cavity semiconductor laser (ECSL) into optical time lens with noise phase modulation. Simulation results indicate consistent elimination of the ECSL relaxation oscillation frequency domination over the RF spectrum for large scale parameters of the optical time lens module and a wideband flat chaos, whose efficient bandwidth rapidly increases with the bandwidth of the noise signal driving the phase modulator and phase modulation index. Besides, we show that the time delay signature suppression can be concurrently achieved for moderate values of the noise bandwidth and phase modulation index. The proposed wideband mmW flat chaos exhibits great potential applications for ultrahigh-speed chaos communications, mmW radars and macroscopic mmW noise source required for mmW research and design.

The use of intensity-based phase-sensitive optical time-domain reflectometry (φ-OTDR) system to measure low-frequency vibration is the aim of this paper. It is well-known that the laser frequency drift (LFD) and other system noise act as internal vibration that challenge φ-OTDR system to capture external low-frequency vibration. We proposed theoretically and demonstrated experimentally that by adapting the probe pulse repetition rate/pulse period to the frequency of vibration to be measured, consistent intensity change should be always realized in the disturbance region compared to the induced phase-noise change from pulse to pulse. In particular, two different pulse periods were used to demonstrate the effectiveness of the adaptive pulse period method (APP) for detection of low-frequency vibration. Experimentally, the sensing of external vibrations of 5; 1; 0.5 and 0.1 Hz frequencies with intensity-based φ-OTDR system was achieved with good signal-to-noise ratio. Moreover, an approach suitable for measuring low-frequency vibration induced by a PZT through direct acquisition of the Rayleigh intensity in the disturbance region was established. Various driving voltages applied to the PZT confirmed the consistency of the method.

Indigenous people have used architecture over millennia to adapt to climatic factors and achieve stable and comfortable living. These adaptations can still inform the design of contemporary regional architecture. In order to explore the relationship between traditional dwellings and climatic factors, we examine buildings in four provinces and cities in southwest China. A database was created using detailed data obtained from the literature on indicators of climatic factors (e.g., temperature, precipitation, temperature difference, wind speed, solar radiation) and architectural elements (e.g., roof slope and eave length). Thorough statistical analysis shows that (1) MPWM has the most significant correlation with the slope angle of traditional building roofs but is not recommended as a predictor in multivariate equations. (2) Temperature and wind speed were significant correlates of roof slope, and a multiple regression model dominated by AMT and AWS serves as a good predictor of roof slope. (3) Solar radiation was not correlated with roof slope but was the largest correlate of eaves length in traditional buildings. AMSR and AWS also dominantly affect eaves length in a regression relationship. These results serve not only as a reference to catalog the use of traditional passive technologies but can guide the design of green buildings. However, more research is needed to refine the use of passive technologies to adapt to climate change

With the widespread application of big data, the amount of data transmitted through optical networks has been increasing dramatically. Correlated random bit generation (CRBG) is one of the key technologies in secure communication systems to ensure security performance and transmission efficiency. We propose and demonstrate a CRBG scheme based on a Mach–Zehnder modulator (MZM) electro-optic feedback loop to improve the security and speed of communication systems. In this scheme, common-signal-induced synchronization is accomplished to generate wideband complex physical entropy sources, and a private hardware module is employed to perform post-processing and nonlinear transformation of the synchronized signal. The simulation results show that the effective bandwidth of the output chaotic signal is significantly increased to 27.76 GHz, and high-quality synchronization with a correlation coefficient of over 0.98 is reached. A high-rate CRBG of up to 5.3 Gb/s is successfully achieved between two synchronized wideband physical entropy sources, and the hardware key space is enhanced to ∼242, which greatly improves the privacy of physical entropy sources. The proposed scheme provides a promising approach for high-speed private CRBG, which is expected to be used in high-speed secure key distribution and optical communication systems.

We present a photonic approach for fast quantum random number generation based on optically sampled amplified spontaneous emission (ASE). This approach utilizes a terahertz optical asymmetric demultiplexer to sample the ASE and then digitize the sampled optical pulses into random bits using a multi-bit parallel comparator. A proof-of-concept experiment demonstrates that 40 Gb/s random bits with verified randomness can be obtained using our method. The current generation rate is mainly limited by the bandwidth of the available ASE source.

The loss and fragmentation of natural spaces in rapidly urbanized areas have greatly reduced their capacity to provide multiple ecosystem services (ESs). It is of great importance to identify natural spaces with key ecological functions, which are used to construct effective and efficient ecological networks, especially in urbanized areas where natural spaces are limited. This paper individually evaluated five key ESs provided by natural spaces in the Su-Jia-Hu area. By constructing an evaluation model coupling individual ESs, the multi-ecosystem service capacity index (MESC index) of each natural space was calculated. The index evaluation results showed that the overall level of ES supply was the highest in the two types of natural space, which were lakes and forests. The results of the clustering analysis on this basis showed that the natural space priority could be divided into six grades: the first grade was the large ecological conservation area, the second and third grades were the important ecological hubs, and the fourth, fifth and sixth grades were the potential stepping stones and structural corridors. The method based on the MESC index evaluation proposed here provided a scientific and repeatable framework for the identification and management of important natural spaces in ecological network planning and useful reference information for planners and decision makers.

True random number generators (TRNGs) are a fundamental resource in information security and can guarantee the absolute security of information in principle. Entropy source is the most critical part of TRNGs, which provides the unpredictability and is the root of security for TRNGs. Electrical noise, which is inevitable and unpredictable in electronic systems, is always used as entropy source for TRNGs. This review discusses the different methods to harvest electrical noise in TRNGs, including the early amplify noise based on amplifier, phase jitter based on oscillator, the effect of electrical noise on the metastable behavior and amplify noise based on chaos circuits. Each method has its own strengths in aspect of speed, cost, complexity and portability. Finally, some post-processing technologies and TRNG evaluation methods are also discussed. With this review, we hope the current spots for TRNGs using electrical noise are summarized and some possible future directions are pointed out.

The method presented is helpful for assessing effects of land use policy and unfolding the action mechanism and implementation effect of policies on land use changes. The backcasting method is based on the re-simulation of the historical real changes of land use. By observing the error between the real and simulated states, adjust the parameters for many times, and a variety of land use scenarios are obtained, and the scenario with the minimum and acceptable error is selected to assess the effects of land use policy represented by its parameters. The method is structured in four sequential stages, including expressing the policy action mechanism as the parameter combinations to control land use changes, and then translating the parameter combination that can reflect the effect of land use policies into the policy effectiveness. This process is realized by ArcGIS and GeoSOS-FLUS software developed based on Cellular Automata (CA) model. The method was successfully tested in the peri-urban region near Shanghai metropolitan area. The raw material is Land-Use/Cover (LULC) data of study area in 2000 and 2015. This method assessed the effects of land use policies during fifteen years, and analyzed the mechanism of effective policies, as well as the types and reasons of failure policies. This presented method is useful in land governance and the formulation and implementation of land use policy. • This article developed a backcasting approach to evaluate the effectiveness of land use policies on land use changes in a certain period of time. • The policy action mechanism was transformed into controllable, visible, and adjustable parameter combinations. • The method built an analytical framework for the assessment of land use policy effectiveness in any regions. Method name: Backcasting approach with multi-scenario simulation (BAMSS), Keywords: Cellular Automata model, Conversion cost matrix, Parameter translation, Land use simulation, Policy effectiveness

We propose a high-sensitivity fiber fault detection method using the feedback-delay signature of a modulated semiconductor laser. The modulated laser is directed to a fiber fault and then receives the fault echo, which, in principle, forms an external cavity feedback laser. The fault location, i.e., the external cavity length, is measured by the feedback-delay signature appearing on the laser modulation response curve. The resonance effect between the modulation frequency and external cavity frequency significantly enhanced the laser sensitivity to feedback light and then led to highly sensitive fault detection. Numerical simulations based on laser rate equations predicted that −118.1 dB sensitivity to fault echo light can be obtained.

Water-flow-regulating ecosystem services (ESs) determine the regulation of hydrological flows on the ground’s surface. A lack of water-flow-regulating ESs would cause environmental problems such as heavy rainfall runoff and urban water logging, leading to floods affecting well-being, especially in dense urban areas. Research on water-flow-regulating ES supply–demand relationships in urban areas is urgently needed to better support the management of urban surface runoff. However, matching the supply–demand relationships of water-flow-regulating ESs remains challenging. In this contribution, a cross-scale approach linking the supply–demand assessment of water-flow-regulating ESs on a macroscale and the evaluation of the constructed urban environment on a microscale was developed. The approach was applied in the city of Bochum, Germany, as a trial of bridging the “science–practice gap”. Our findings show that the supply–demand budget of water-flow-regulating ESs in Bochum exhibits an urban–rural difference and is also partially influenced by land cover transformations such as vegetation degradation. In addition, further assessment of the constructed urban environment confirmed the result from the assessment of water-flow-regulating ESs based on the understanding of the urban hydrological cycle in Bochum. To account for the mismatch in the supply–demand budget, we classified the typical superior and inferior forms of urban water-flow-regulating ESs through field research on the same extreme areas to summarize the operable optimization, enhancement, and protection suggestions for urban construction decision makers. Finally, the cross-scale approach was approved as a possible way to bridge the “science–practice” gap for water-flow-regulating ES research in urban areas.

Context: Without clear understanding of the units used for ecosystem service (ES) mapping, ES assessment accuracy and the practical application of ES knowledge will be hampered. Method: We systematically reviewed 106 studies over the past 11 years to explore the type, characteristic pattern and deficiencies of mapping units. Result: We proposed that ES mapping units can be categorized into minimal unit for assessing ESs using corresponding indicators and methods, and aggregated unit for analysis and application based on research objectives, and classified the mapping units into five common types. Of the 12 characterizing variables of ES mapping studies, some have been shown to introduce a difference in the selection of mapping units and to exhibit characteristic patterns. We also found that the accuracy of ES assessments based on minimal units was lacking, and aggregated units were insufficient to establish a link between ES knowledge and practice. Conclusion: Herein, we propose possible solutions such as the use of fine spatial resolution grids and the introduction of additional data beyond land cover as supplements to improve the assessment accuracy. To enhance the availability of the results for practice, aggregated units connected with urban planning units should be established at a spatial level suitable for urban management.

When a tunnel is excavated in the water-rich soft rock stratum, the strength of the soft rock is greatly reduced due to the seepage of groundwater. The condition may result in engineering accidents, such as large deformation, limit invasion, and even local collapse of the tunnel. Therefore, it is very important to research the stability of the surrounding rock in the water-rich soft rock tunnel. The water-rich disturbance factor considering the seepage influence of groundwater and blasting disturbance is proposed, and the generalized Hoek–Brown strength criterion is modified on the basis of the immersion softening test of soft rock. In accordance with the classical elastic–plastic mechanics theory, the stress, strain, and displacement calculation formulas of the tunnel surrounding rock are derived. The displacement of tunnel surrounding rock is analyzed using the derived formula and the modified Hoek–Brown strength criterion and then compared with the measured value. Results show that the displacement of surrounding rock, which is calculated by modified Hoek–Brown strength criterion considering water-rich disturbance factor and the displacement calculation formula, is close to the measured deformation of surrounding rock in water-rich soft rock tunnel, and the error is small. Therefore, the modified Hoek–Brown strength criterion can be applied to the water-rich soft rock tunnel, and the derived displacement calculation formula can accurately calculate the deformation of tunnel surrounding rock. It is of great significance to the study of surrounding rock stability of water-rich soft rock tunnel.

Initial geostress has great influence on the properties of gneiss. The physical and mechanical properties of gneiss vary considerably due to different initial geostresses, which exert a huge effect on the stability of underground engineering. In order to explore the influence of initial ground stress on the properties of gneiss. Changes in the physical properties (e.g., P-wave velocity and volumetric weight), mechanical properties (e.g., compressive strength, elastic modulus, and residual strength) and failure mode of gneiss are analyzed by conducting physical and mechanical tests on gneiss in different ground stress areas. The results show that high geostress can improve the pre-peak mechanical properties of gneiss, and weaken its post-peak mechanical properties. When the initial geostress is greater, the pre-peak mechanical properties are better, and the post-peak mechanical properties are worse. The failure mode of gneiss under high ground stress is primarily brittle failure. When the initial ground stress is greater, brittleness is stronger. According to the research results of this paper, it can provide the basis for the optimization and improvement of underground engineering support in gneiss strata with high geostress. The research results have important reference value and guiding significance for underground engineering construction in high geostress gneiss areas.

Ecological restoration has become an important tool for mitigating and adapting to environmental degradation caused by global urbanization. However, current research has focused on single indicators and qualitative analysis, meaning that ecological restoration has not been effectively and comprehensively addressed. This study constructed a spatial priority identification system for ecological restoration, with landscape area, landscape structure and landscape function as the core indicators. The system has wide adaptability. In this work, the spatial classification of ecological degradation was performed by overlay analysis. The results showed the following: (1) In the Shanghai metropolitan area, the landscape quality showed a trend of degradation, with built-up areas encroaching on forests and cropland. (2) Ecological degradation in the suburbs was more severe than that in the urban center. Forests had the highest landscape area indicator (LAI) stability. Significant degradation of landscape structure indicators (LSIs) occurred when built-up area and cropland were transformed into forests. (3) Different types of ecological restoration had significant spatial distribution patterns. Through this identification system, this study aimed to help planners/managers of ecological restoration to recognize the changing patterns of regional landscape quality and its relationship with land cover. It ultimately provides a basis for the formulation of regional ecological objectives and spatial strategies.

Due to intense anthropogenic impacts, river networks in co-urbanized areas are severely degraded and fragmented, and their ability to supply multiple ecosystem services is greatly reduced. This study aimed to provide a novel technical approach to identify spatial priorities for complex and special linear water spaces in a co-urbanized area. This approach fully considers the features of river networks with multiple levels and multiple functions. We first identified two spatial configurations of river networks based on the river density: river cluster patches and river corridors, which were each divided into four spatial levels. We then assessed and mapped the multiple ecosystem services provided by each river level through a coupling evaluation model. Finally, based on the evaluation results and spatial clustering analysis, we identified priorities of linear water spaces using six priority grades. This priority identification method based on multiple levels and multiple ecosystem services of linear water spaces shows how a holistic catchment perspective can be applied to the practice of integrated river management in co-urbanized areas. Selecting conservation strategies for linear water spaces on the basis of their structural level and ecological contribution is a more targeted measure.

We experimentally demonstrate a real-time high-speed physical random bit generator using the time-interleaved sampling of broadband white chaos. The white chaos is generated by optical heterodyning of two external-cavity feedback laser diodes. It has a white-noise-like spectrum with a 3-dB bandwidth of 16.7 GHz and a symmetric amplitude distribution and has no time-delay signatures of the external feedback cavities. An analog-to-digital converter (ADC) chip integrated by two time-interleaved sub-ADCs with a maximum sampling rate of 7 GHz is utilized to discretize the white chaos into parallel binary streams. After real-time interleaving combination and exclusive-OR operation in the field-programmable gate array (FPGA), a 14-Gbps binary stream with verified randomness is achieved.

The cooling and humidifying effects of urban aggregated green infrastructure can provide essential services for city ecosystems, regulating microclimates or mitigating the urban heat island effect. However, the optimal thresholds of plant community structure parameters for maximizing the associated cooling and humidifying effects remain unclear. In this paper, we use the method of dummy variable regression to measure plant communities in an urban aggregated green infrastructure. By examining the relationships between the cooling and humidifying effects and plant community structure parameters (i.e., canopy density, porosity, and vegetation type), we introduce optimal thresholds for the parameters. We find that canopy density has a significantly positive correlation with both cooling and humidifying effects, while porosity has a positive correlation with cooling and a negative one with humidifying. Different vegetation types have distinct influences on cooling and humidifying effects. When the canopy density is between 0.81 and 0.85 and the porosity is between 0.31 and 0.35, the cooling and humidifying effects of the plant communities reach their peak. Additionally, the greening coverage rate and spatial types of urban aggregated green infrastructure have influences on cooling and humidifying effects. The findings can help us to better understand the relationships between plant community structure parameters and their temperature regulation functioning for urban aggregated green infrastructure. This study provides guidelines and theoretical references for the plant configuration of future urban green spaces.

In this paper, a deep learning (DL)-based predictive analysis is proposed to analyze the security of a non-deterministic random number generator (NRNG) using white chaos. In particular, the temporal pattern attention (TPA)-based DL model is employed to learn and analyze the data from both stages of the NRNG: the output data of a chaotic external-cavity semiconductor laser (ECL) and the final output data of the NRNG. For the ECL stage, the results show that the model successfully detects inherent correlations caused by the time-delay signature. After optical heterodyning of two chaotic ECLs and minimal post-processing are introduced, the model detects no patterns among corresponding data. It demonstrates that the NRNG has the strong resistance against the predictive model. Prior to these works, the powerful predictive capability of the model is investigated and demonstrated by applying it to a random number generator (RNG) using linear congruential algorithm. Our research shows that the DL-based predictive model is expected to provide an efficient supplement for evaluating the security and quality of RNGs.

We propose a real-time self-balanced photonic method for extracting ultrafast random numbers from broadband randomness sources. In place of electronic analog-to-digital converters (ADCs), the balanced photo-detection technology is used to directly quantize optically sampled chaotic pulses into a continuous random number stream. Benefitting from ultrafast photo-detection, our method can efficiently eliminate the generation rate bottleneck from electronic ADCs which are required in nearly all the available fast physical random number generators. A proof-of-principle experiment demonstrates that using our approach 10 Gb/s real-time and statistically unbiased random numbers are successfully extracted from a bandwidth-enhanced chaotic source. The generation rate achieved experimentally here is being limited by the bandwidth of the chaotic source. The method described has the potential to attain a real-time rate of 100 Gb/s.

We propose a combined attenuation and high-resolution fault measurement method using chaos optical time-domain reflectometry (OTDR). Utilizing the pulse-modulated chaotic light and correlation operation, this technique realizes fiber attenuation measurement and a distance-independent spatial resolution simultaneously. We demonstrate a proof-of-concept experiment for measurements of a single-mode fiber (G.652) and a fiber link consisting of a single-mode fiber (G.652) and a conventional (62.5-μm) multimode fiber. The measurement results show that different attenuation coefficients can be measured, and the coefficients agree well with the values obtained by using conventional OTDR. A 0.6-m resolution is achieved with a data acquisition bandwidth of 200 MHz.

We propose a method with high spatial resolution to detect fiber faults in a time-division multiplexing passive optical network (TDM-PON). A semiconductor laser serving as the probe light source is subjected to self-feedback caused by reflection at fiber faults. The feedback will induce the laser to generate chaos. Autocorrelation of the output time series shows the external cavity signature and, therefore, indicates the distance between the laser and the fiber fault. Each branch is identified by the marker that is formed by the inserted fiber Bragg grating (FBG) providing the feedback in each branch, and the faulty branch can be distinguished by the marker that has disappeared. Our proof-of-concept experiment demonstrates the identification of the faulty branch and the location of the fault point in an optical network simultaneously. This is achieved with a 6-km feeder fiber and realizes the 8-mm spatial resolution.

An incoherent Brillouin optical time-domain reflectometry with random state correlated Brillouin spectrum is proposed and experimentally demonstrated for the first time, which is based on a newly developed broadband random light source (chaotic laser) with a bandwidth of four times of the Brillouin spectral width in fiber. A variable optical delay line is introduced to provide location distribution of the temperature or strain in the fiber to replace the optical pulse generator. By adjusting the reference light path, the correlation of the same random state of the Stokes light and the pump light will be measured in the form of the Brillouin spectrum. The spatial resolution is inversely proportional to the bandwidth of the chaotic laser, and hence, the pump wave and Stokes wave are correlated to each other by their identical random state. The experimental result shows a 0.96-m spatial resolution (limited by the bandwidth of the chaotic laser) over a 155-m sensing range.

A multiwavelength single-longitudinal-mode (SLM) Brillouin-erbium fiber laser sensor with ultrahigh resolution is proposed and investigated experimentally. The one short common cavity with 50 m of single mode fiber (SMF) as the fiber under test and 100 m of SMF as the reference can effectively reduce the external perturbations and the cost. With the configuration that uses a fiber Fabry-Pérot (FFP) filter, every Stokes wavelength maintains SLM status, which can lead to the higher temperature resolution. In the experiment, 3.104 MHz/°C sensitivity of the third-order Stokes wavelength is demonstrated, which is three times that of the first-order Stokes wavelength. A less-than 0.2 °C temperature error is obtained for every Stokes wavelength. In contrast, with a beat frequency linewidth of a different order Stokes wavelength, approximately 10-6°C ultrahigh resolution in the short term is acquired at the third-order Stokes wavelength. This proposal can provide a feasible temperature sensing scheme with high sensitivity, high precision, and low-frequency detection.

We propose a scheme for random bit generation with filtered amplified spontaneous emission (ASE). Using the filtered ASE, we can get larger signal fluctuations than when using directly detected ASE with a photodetector. Utilizing the delayed self-difference technique to improve the symmetry of filtered ASE, we experimentally achieve real-time 2.5-Gbit/s random sequence generation, which matches with the speeds of fiber communication for one-time pad encryption. Experimental results show that the generated random sequences can pass NIST tests as long as the delay time is beyond a threshold value, which is called the minimum delay time (MDT). Further simulation results indicate that there is a certain relationship between the MDT and bandwidth of the ASE signal.