We propose and demonstrate a pulsed-chaos multiple-input-multiple-output (MIMO) radar system in this paper. In the proposed MIMO radar system, multi-channel pulsed chaotic signals are extracted from ...an optical seed chaos source with Delta-like autocorrelation and flat spectrum. The seed chaos source is generated by passing the chaotic output of an external-cavity semiconductor laser through a dispersive self-feedback phase-modulation loop and used for MIMO radar signal generation. The cross-correlation characteristics of MIMO radar signals, the maximum channel number of separable mixed echoes, as well as the performances of multi-target ranging and anti-interference in the proposed pulsed-chaos MIMO radar system are systematically investigated. The results indicate that multi-channel pulsed-chaos signals with Delta-like autocorrelation can be simultaneously generated from the seed chaos source, and excellent quasi-orthogonality of transmission radar signals can be guaranteed. Moreover, it is demonstrated that the proposed pulsed-chaos MIMO radar supports multi-target ranging with a centimeter-level resolution and can maintain satisfactory performance under low SNR scenarios with various interferences.
Purpose: This systematic review aimed to identify and evaluate the effectiveness of the main child neglect measures published between 2003 and 2023. Method: Six databases were searched. The ...methodological quality and psychometric properties of the identified measures were appraised through the COnsensus-based Standards for the selection of health Measurement INstruments checklist. Results: A total of 39 measures were identified across the 66 studies that met the relevant inclusion criteria. The most commonly used measurement tool was The Childhood Trauma Questionnaire (original or modified version), with the Child Neglect Questionnaire also showing great promise. Internal consistency was the most reported and robust psychometric property, with responsiveness, criterion validity, and measurement error being understudied. Conclusion: No instrument demonstrated a sufficient level of evidence across all criteria. Further research is required to validate the effectiveness of new and existing instruments. This can be achieved by employing higher-quality methods and assessing all psychometric properties.
State Infrastructure Banks (SIBs) are established to provide low-interest loans and credit enhancements to assist local governments in financing transportation projects. SIB loans, one of their core ...products, are low-cost and low-risk when compared to traditional capital finance tools. However, SIB loans are still rarely used by local communities. This study investigates the determinants of local government adoption of SIB loans among Pennsylvania municipalities from 2008 to 2015. Using limited dependent variable models, we discover that infrastructure demands, prior experiences, and neighboring adoptions are all positively associated with municipalities’ likelihood of applying for SIB loans as well as the intensity of loan usage, whereas fund balance reduces the probability of applying for SIB loans. We also find that as fund balance increases, the positive impact of infrastructure demands diminishes.
We propose a type of semiconductor laser (SL) network that supports flexible chaos synchronization and multipoint-to-multipoint communications by using one-way isolation (OWI). The properties of ...chaos synchronization, influences of coupling strength and time delay mismatches on the quality of chaos synchronization, and the performance as well as the security of the SL network-based chaotic communications are systematically discussed. The numerical results demonstrate that, with the introduction of OWI, flexible chaos synchronization can be easily achieved in arbitrary-size SL clusters over wide parameter spaces of coupling strength and current factor. Based on the high-quality flexible chaos synchronization, satisfactory performance for Gb/s chaotic communications can be achieved in arbitrary-size clusters in the SL networks. Moreover, it is also indicated that in the SL networks, the security of intra-cluster communications can be guaranteed in three aspects. Firstly, the eavesdroppers cannot intercept any useful information by using a typical illegal attack. Secondly, due to the OWI, the chaotic carriers are only transmitted in the corresponding clusters, not transmitted among clusters, as such the security can be further improved. Thirdly, the high sensitivity of cross-correlation coefficient to the injection delay mismatches indicates that the injection delays of idle SLs to communicating SLs can be regarded as the keys of the communication clusters. The proposed scheme offers an alternative solution to flexible secure network-type communications.
We propose and experimentally demonstrate a novel multi-channel chaos generation scheme, which can simultaneously produce multiple chaotic signals with wideband spectrum and suppressed time-delay ...signature (TDS). In this scheme, we introduce an external self-phase-modulated feedback (ESPMF) to improve the optical bandwidth of the initial chaos generated by a conventional external-cavity semiconductor laser (ECSL), then optical tunable filters (OTFs) are utilized to simultaneously extract three-channel chaotic outputs. The experimental results show that the proposed scheme has three main advantages. Firstly, it can simultaneously generate multiple chaotic outputs with different central wavelengths and low correlations. Secondly, the bandwidth of original ECSL-based chaos can be improved by several times, and the undesired TDS characteristics in the original chaos can be completely suppressed to an indistinguishable level (lower than 0.02). Thirdly, the bandwidths of these chaotic outputs are flexible and can be adjusted within a wide range of 20 GHz by controlling the filter bandwidths. In addition, we demonstrate an application of the proposed chaos generation scheme in random bit generation (RBG), and multi-channel high-speed random bit sequences with a total generation rate over Tb/s and NIST verified randomness are simultaneously obtained.
•Two types of bamboo cellulose fiber-based functional materials were fabricated.•Structural materials from cellulose I had the highest tensile strength (571 MPa).•Flexible electrode materials from ...cellulose II had areal capacitance of 2032 mF cm−2.•Differences between bamboo cellulose I and II were compared.
Degradable and sustainable materials are needed to reduce pollution and energy consumption. Bamboo, an inexpensive and abundant resource, can be used to develop such materials. To this end, we demonstrate two types of bamboo-fiber-based functional materials. The first can be used as structural materials with outstanding anti-mildew properties (ultra-high tensile strength: 571 MPa; compressive strength: 191 MPa; surface hardness: 227 MPa) and is produced with long and aligned bamboo cellulose I fibers mixed with epoxy. The second is suitable for electrodes in wearable devices (areal capacitance: 2032 mF cm−2; linear capacitance: 670 F cm−1; energy density: 139.3 µWh cm−2; power density: 80.4 µW cm−2) and uses nickel-coated bamboo cellulose II fibers. The design strategies of bamboo-fiber-based functional materials demonstrated in this study provide new insights for novel degradable and sustainable functional materials.
We propose and numerically demonstrate a novel secure key distribution (SKD) scheme by using dynamically synchronized semiconductor lasers (SLs) subject to common dual injections from two mutually ...coupled SLs. The performance of hybrid chaos synchronization, complexity of chaotic signals, chaos-based key distribution, and the privacy of SKD scheme are systematically discussed. It is shown that high-quality hybrid chaos synchronization of zero lag and lead lag can be both achieved between two local lasers under different injection delay conditions, whereas low cross correlations are observed among the driving lasers and the local lasers. By randomly perturbing the injection delays with four independent random sequences, the outputs of local SLs can be dynamically synchronized. Extracting the outputs in the synchronization time slots of zero lag and lead lag, synchronous entropy sources are obtained and used to generate keys with high consistency at local ends of Alice and Bob, which are robust to the parameter mismatches of local lasers to some extent. Moreover, large BER is calculated in two types of typical illegal attacks, which demonstrates the security of the proposed scheme. This work proposed a high-level secure key distribution solution to one-time pad communication.
Purpose: This study examined the feasibility, acceptability, and preliminary effectiveness of Parenting for Lifelong Health for Parents and Adolescents program in reducing the risk of child ...maltreatment in Chinese families with adolescents. Methods: A pre-post single-arm pilot trial was conducted in July and August, 2023, and involved 16 parents and 13 teenagers with a mixed-methods design to collect both quantitative and qualitative data. Results: Parents reported enhanced positive parenting and reduced child behavioral problems. Adolescents reported decreased general child maltreatment and emotional maltreatment, along with perceived improvements in positive parenting and parent-child communication. Thematic analyses suggested of tangible benefits for participants, as well as for their family dynamics. Discussion: The program demonstrated promising feasibility, and it was significantly associated with reduced adolescent maltreatment. Further rigorous randomized controlled trials are needed.
Regression is a powerful tool to study how the response variables vary due to changes of explanatory variables. Unlike traditional statistics or mathematics where data are assumed fairly accurate, we ...notice that the real-world data are messy and obscure; thus, the uncertainty theory seems more appropriate. In this paper, we focus on the residual analysis of the Johnson–Schumacher growth model, with parameter estimation performed by the least squares method, followed by the prediction intervals for new explanatory variables. We also propose a
k
-fold cross-validation method for model selection with imprecise observations. A numerical example illustrates that our approach will achieve better prediction accuracy.
We propose a novel wideband chaos generation scheme by using an external-cavity semiconductor laser (ECSL) subject to optical-electronic hybrid feedback. In this scheme, the output of ECSL is ...photo-detected and used to modulate the output of a continuous wave laser by an electro-optical phase modulator, the constant-amplitude self-phase-modulated light is then injected back into the ECSL. The experimental results indicate that, compared with the chaos generation with conventional optical feedback (COF), significant bandwidth enhancement is achieved in the proposed scheme. The effective bandwidth of generated chaos is increased from a few GHz to over 20 GHz, and moreover, the spectrum flatness and the complexity of generated chaos are also considerably improved. Furthermore, we propose a wideband chaos synchronization system based on the proposed chaos generation scheme. It is experimentally demonstrated that high-quality synchronization between two wideband chaos signals with an effective bandwidth greater than 20 GHz is achieved. This work simultaneously achieves the generation and the synchronization of wideband chaos, which shows valuable potential in chaos-based secure communication, such as enhancing the transmission capacity and improving the security.
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