Passive Scenario Research Articles

Real-time regulation of detention ponds via feedback control: Balancing flood mitigation and water quality

Detention ponds can mitigate flooding and improve water quality by allowing the settlement of pollutants. Typically, they are operated with fully open orifices and weirs (i.e., passive control). Active controls can improve the performance of these systems: orifices can be retrofitted with controlled valves, and spillways can have controllable gates. The real-time optimal operation of its hydraulic devices can be achieved with techniques such as Model Predictive Control (MPC). A distributed quasi-2D hydrologic-hydrodynamic coupled with a reservoir flood routing model is developed and integrated with an MPC algorithm to estimate the operation of valves and movable gates in real-time. The control optimization problem is adapted to switch from a flood-related algorithm focusing on mitigating floods to a heuristic objective function that aims to increase the detention time when no inflow hydrographs are predicted. The case studies show the potential results of applying the methods developed in a catchment in Sao Paulo, Brazil. The performance of MPC compared to alternatives that do not change the operation over time with either fully or partially open valves and gates are tested. Comparisons with HEC-RAS 2D indicate volume and peak flow errors of approximately 1.4% and 0.91% for the watershed module. Simulating two consecutive 10-year storms shows that the MPC strategy can achieve peak flow reductions of 79%. In contrast, the passive scenario has nearly half of the performance (41%). A 1-year continuous simulation results show that the passive scenario with 25% of the valves opened can treat 12% more runoff compared to the developed MPC approach, with an average detention time of approximately 6 h. For the MPC approach, the average detention time is nearly 14 h, indicating that both control techniques can treat similar volumes; however, the proxy water quality for the MPC approach is enhanced due to the longer detention times achieved.

Mean airway pressure - Minute ventilation product (mM): A simple and universal surrogate equation to calculate mechanical power in both volume and pressure controlled ventilation

Introduction Mechanical power represents the energy delivered by a mechanical ventilator onto the lungs. It incorporates all the variables participating in ventilator-induced lung injury, including driving pressure, tidal volume, positive end expiratory pressure, and respiratory rate. The pitfall of mechanical power is its mathematical complexity, as the gold standard method of calculation involves deriving the inspiratory area under the pressure-volume curve of each breath. Prior studies attempted to create simplified equations, they lack clinical utility as calculations cannot be done by solely looking at ventilator settings or they require manipulation of variables. There are also different formulas depending on the type of the mode of ventilation used. This study offers a simplified, universal equation called the mean airway pressure - Minute ventilation product (mM equation) which renders mechanical power clinical application more feasible at the bedside. Methods and Statistics Data collection used the online SIVA simulator, which simulate mechanical ventilation and calculate the geometrical area of the inspiratory limb of the pressure-volume curve. Different combinations of passive scenarios with varying compliances (10-80 ml/cmH2O) and resistances (5-30 cmH2O/L/S) in each the VCV and PCV modes were accomplished by adjusting ventilator settings with respiratory rate (5-40 BPM), tidal volume (150-700 mL), DP (5-30 cmH2O), and PEEP (0-15 cmH2O), with different inspiratory times in PCV and different flows rates in the VCV. A total of 2,000 values were collected in each mode. Range of Mechanical power measured by the simulator: 0.1 - 105 J/min and range of mM equation (mean airway pressure x Minute ventilation): 0.37 - 820 cmH2O/L/min. Pearson correlation coefficients were calculated to compare the relationship of the mM equation to the measured MP, and linear regressions were used for predicting the MP derived from the mM equation in each mode separately and when combining all data from both modes. T-test for equal variance and Bland Altmann plot were used to compare the reference MP measured (MPR) from the simulator to the one derived from the Mm formula (MPD). Results There was a statistically significant linear relationship (P < 0.001) and strong correlation of determination (R2 = 0.931), CI (0.961, 0.967) between the mM formula and the gold-standard method of calculating mechanical power for the combined two modes. For the VCV: there was a statistically significant linear relationship (P < 0.001) and strong correlation of determination (R2 = 0.936), CI (-0.963, 0.971). For the PCV: there was a statistically significant linear relationship (P < 0.001) and strong correlation of determination (R2 = 0.936), CI (-0.964, 0.970). A linear regression model predicted the MP from the mM as follows: for both modes MP = 0.13 (mM) + 3.41, for PCV MP = 0.15 (mM) + 3.79, for VCV MP = 0.13 (mM) + 2.48. The derived mechanical power from the mM was not statistically different (P 0.498) from the calculated reference MP using two sample T-tests assuming equal variance. The Bland-Altman plot for VCV mode showed a mean of 0.78 with 95% CI (0.34, 1.22), SD (-13.27, 14.83). In PCV, a mean of - 0.53 with 95% CI (-0.68, -0.38), SD (-6.28, 5.22). For both modes, a mean of 0, with 95% CI (-0.2, 0.2), SD (-10.06, 10.05). Conclusion The mM equation and its MP derived formula is a reliable method of calculating mechanical power. The simplicity and universal nature of its calculation can provide significant clinical utility at the bedside. More studies are needed to validate this method of calculation. Keywords: Mechanical power, mean airway pressure, minute ventilation

Avalanche properties at the yielding transition: from externally deformed glasses to active systems.

We investigated the yielding phenomenon in the quasistatic limit using numerical simulations of soft particles. Two different deformation scenarios, simple shear (passive) and self-random force (active), and two interaction potentials were used. Our approach reveals that the exponents describing the avalanche distribution are universal within the margin of error, showing consistency between the passive and active systems. This indicates that any differences observed in the flow curves may have resulted from a dynamic effect on the avalanche propagation mechanism. The evolution time required to reach a steady state differs significantly between active and passive scenarios under similar conditions. However, we demonstrated that plastic avalanches under athermal quasistatic simulation dynamics display a similar scaling relationship between avalanche size and relaxation time, which cannot explain the different flow curves.

Phase behavior and dynamics in a colloid-polymer mixture under spherical confinement.

From studies via molecular dynamics simulations, we report results on structure and dynamics in mixtures of active colloids and passive polymers that are confined inside a spherical container with a repulsive boundary. All interactions in the fully passive limit are chosen in such a way that in equilibrium coexistence between colloid-rich and polymer-rich phases occurs. For most part of the studies the chosen compositions give rise to Janus-like structure: nearly one side of the sphere is occupied by the colloids and the rest by the polymers. This partially wet situation mimics approximately a neutral wall in the fully passive scenario. Following the introduction of a velocity-aligning activity to the colloids, the shape of the polymer-rich domain changes to that of an ellipsoid, around the long axis of which the colloid-rich domain attains a macroscopic angular momentum. In the steady state, the orientation of this axis evolves via diffusion, magnitude of which depends upon the strength of activity, but only weakly.

Forest-Wide Longleaf Pine Restoration Response to Varying Future Management Intensities in a Transitioning Upland Forest

Abstract Many public land management programs in the southeastern United States have been restoring the longleaf pine forest for more than 20 years, which includes intensive treatment with fire, thinning, chemical control of competition, and tree planting. A shift to more passive management (prescribed burning alone) is anticipated once a critical level of longleaf pine has been established. It remains unclear whether this longleaf pine threshold has been reached and whether intensive management should continue at Fort Benning, Georgia. Using the Landis-II forest landscape model, changes in tree species and forest types were estimated from 2017 to 2117 under four forest management scenarios, ranging from passive (“burn only”) to intensive (“proactive”). The desired future condition includes 75% of upland forest dominated by longleaf pine (>49.5% composition). The proactive scenario resulted in the desired future forest condition, whereas reactive and passive scenarios did not. These results suggest a critical threshold of longleaf pine forest has not been reached at Fort Benning and therefore intensive management approaches are still required. This study shows that even well-established populations of longleaf pine on public lands require maintenance and continued intensive restoration to reach desired forest-wide conditions.

From inequalities to territorial inequalities. An approach to the agency of the territory

In recent decades, the study of inequalities has become a central theme in the research agendas of the social sciences. As a result of this interest, there is currently an abundant production in which a diversity of forms of interpretation, measurement and conceptualization coexist, which, in turn, present different and, in some cases, opposing theoretical approaches. In parallel with these debates, there has recently been a progressive concern for understanding the socio-spatial or territorial dimension of social inequalities. However, until now, most disciplines, with the exception of geography, have given little importance to the territory or geographic space where these inequalities are developed and reproduced. Based on a theoretical-documentary research, the intention of this paper is to present a general approach to the relationship between inequalities and territory, starting with two fundamental questions: what are the implications for the analysis of inequalities of recognizing the agency of the territory, ¿and what role does the territory play in the production and reproduction of inequalities? In conclusion, the need to recover the idea of "territorial agency" is emphasized, since the territory should not be seen as a mere support or passive scenario where inequalities develop. This notion makes it possible to understand the inequalities/territory dialectic and to observe it as an active mediator in the configuration of these inequalities. 

Passive indoor visible light-based fall detection using neural networks

In this paper, a passive visible light sensing (VLS) fall detection system based on luminaires is proposed that uses neural networks to learn the state (i.e., upright or prone) of a target (e.g., a person). The proposed method measures the channel impulse response (CIR) between different source-receiver pairs in a passive scenario, where the user does not hold a device or sensor. The CIR measurements are collected in a realistically modeled room and neural networks are employed to learn the relationship between the CIR measurements and the states of the target at randomly selected positions in the room. The performance evaluation of the system shows that an accuracy of more than 97% is attainable by utilizing a large number of data samples and high brightness factor of the luminaires. The robustness of the proposed method is validated by using a tilted state which is labeled with same class as the upright state, however, the tilted state is not used to train the network. One of the key applications of fall detection is in healthcare domain for patient monitoring. The correct prediction of the prone state is particularly critical in such scenarios since emergency situations may arise from a fall.

CLAP: A Cross-Layer Analytic Platform for the Correlation of Cyber and Physical Security Events Affecting Water Critical Infrastructures

Water CIs are exposed to a wide number of IT challenges that go from the cooperation and alignment between physical and cyber security teams to the proliferation of new vulnerabilities and complex cyber-attacks with potential disastrous consequences. Although novel and powerful solutions are proposed in the literature, most of them lack appropriate mechanisms to detect cyber and physical attacks in real time. We propose a Cross-Layer Analytic Platform (denoted as CLAP) developed for the correlation of Cyber and Physical security events affecting water CIs. CLAP aims to improve the detection of complex attack scenarios in real time based on the correlation of cyber and physical security events. The platform assigns appropriate severity values to each correlated alarm that will guide security analysts in the decision-making process of prioritizing mitigation actions. A series of passive and active attack scenarios against the target infrastructure are presented at the end of the paper to show the mechanisms used for the detection and correlation of cyber–physical security events. Results show promising benefits in the improvement of response accuracy, false rates reduction and real-time detection of complex attacks based on cross-correlation rules.

Parametric Enhancement of Radiation from Electrically Small Antennas

Electrically small antennas are characterized by large quality factors, which yield limited gain-bandwidth products, as a result of the Bode-Fano limit. This bound implies a trade-off between the antenna's footprint and radiation features, hindering wireless applications that require compact, broadband, and efficient antennas. Here, building on a previous theoretical analysis of parametric matching networks [H. Li, A. Mekawy, and A. Al\`u, Phys. Rev. Lett. 123, 164102 (2019)], we demonstrate how parametric phenomena can overcome this trade-off, offering a pathway to realize stable non-Foster wideband antennas that go beyond the restrictions of passive systems. We demonstrate our approach in a planar small loop antenna loaded by a time-varying capacitor that oscillates around twice the radiation frequency, showing that it can result in wideband radiation enhancement, exceeding the limitations of passive scenarios.

A Passive DOA Estimation Algorithm of Underwater Multipath Signals via Spatial Time-Frequency Distributions

Direction of arrival (DOA) estimation of underwater multipath signals has become an indispensable part of many military and civil applications in the oceanic field. However, DOAs of different paths of the multipath signals may be the same or too close to be separated in space, which brings a great challenge to the DOA estimation of multipath signals. Besides, the number of multipath is generally unknown and time-varying in passive scenarios which generally lead to an underdetermined case. Therefore, it is essential to study an efficient algorithm to realize the underdetermined DOA estimation of underwater multipath signals in passive scenarios. This paper proposes a passive DOA estimation algorithm of underwater multipath signals via spatial time-frequency distributions (STFDs). Firstly, we establish a multipath signals model and utilize the quadratic time-frequency (TF) analysis method to reduce cross-terms while keeping a good resolution. Then, we estimate the number of multipath and introduce a novel multi-ridge detection technique to extract the TF trajectories of multipath signals, which adopts the idea of smoothing forward and backward, and the edge TF point detection strategy. Lastly, we estimate the DOA of each path of the multipath signals separately and realize source association based on the clustering-based method. Simulation results and analysis demonstrate that this algorithm can effectively improve the estimation accuracy of instantaneous frequency (IF) and DOA estimation of underwater multipath signals in underdetermined cases and passive situations.

The Impact of Passive Green Technologies on the Microclimate of Historic Urban Structures: The Case Study of Lodz

Rapid population growth necessitates modifications of urban form, especially in city centers. Consequently, the correlation of the outdoor environment with the occupant’s behavior has profoundly changed. In this study, the authors describe a method, that allows for the estimation of the impact of passive green technologies on the microclimate of historic urban structures, taking into account the city-specific conditions. The Envi-met application, which is widely applied in urban climatology, was used to create the atmospheric processes simulation. Passive scenarios such as green roofs, living facades, and high greenery for chosen periods—warm conditions and the hottest day—were considered. It enabled an assessment of microclimatic outdoor conditions at the pedestrian (1.4 m) and living level (5 m). The results suggested that the highest temperature reduction was related to the tree scenarios (0.09 °C at 1.4 m and 0.18 °C at 5 m height for warm a period; 1.23 °C at 1.4 m and 1.31 °C at 5 m height for the hottest day). The thermal comfort was calculated through the usage of simulated output data. In our investigation, the maximum change in PET was 1.51 °C (for the warm period) and 5.41 °C (during the hottest day of the year). The findings have valuable implications for the design of the city’s structure.

Investigating alternative development strategies for sport arenas based on active and passive systems

Raising energy consumption observed in sport events for the last decades leads the organizing associations to developing adequate countermeasures. While the enhancement of active systems (installed on or integrated in buildings) had been already boosted to increase their efficiency in producing renewable energy, passive strategies still present room for development. The hereby study aims at providing useful information which can orient decision-makers towards wiser choices through the comparison of two alternative configurations, respectively based on active and passive strategies. A building-integrated photovoltaic (BiPV) plant and a cool surface treatment to increase the envelope solar reflectance were investigated in the Dacia Arena football stadium (Italy). Economic and environmental analyses were carried out in order to identify limits and potentials. The variables considered in the analyses included the installing costs, costs for the replacement, earnings due to energy production, profits from Emission Trading System for carbon credits, and savings from reduced energy consumption (if compared to initial configuration). Results demonstrated that highly-reflective coating guarantees a lower impact than BiPV plant in terms of economics, and permits paying back installing costs in a shorter time interval. When it comes to the environmental analyses, the amount of compensated emissions equals around 100 kgCO2-eq/m2 for the passive scenario and 1,500 kgCO2-eq/m2 for the active scenario.

Stereotypes, emotions, and behaviors associated with animals: A causal test of the stereotype content model and BIAS map

Using the stereotype content model (SCM; Fiske, Cuddy, Glick, & Xu, 2002) and the behaviors from intergroup affect and stereotypes (BIAS) map (Cuddy, Fiske, & Glick, 2007), two experiments tested the effect of animal stereotypes on emotions and behavioral tendencies toward animals. As a novel approach, Study 1 ( N = 165) manipulated warmth and competence traits of a fictitious animal species (“wallons”) and tested their effect on emotions and behaviors toward those animals. Stereotypical warm-competent and cold-incompetent “wallons” elicited fondness/delight and contempt/disgust, respectively. Cold-competent “wallons” primarily elicited threat but not awe. Warm-incompetent “wallons” were elusive targets, not eliciting specific emotions. The warmth dimension determined active behaviors, promoting facilitation (support/help) and reducing harm (kill/trap). The competence dimension determined passive behaviors, eliciting facilitation (conserve/monitor) and reducing harm (ignore/let them die off). Study 2 ( N = 112) tested the relation between animal stereotypes for 25 species and realistic scenarios concerning behavioral tendencies toward animals. Similar to Study 1, stereotypically warm (vs. cold) animals matched with active scenarios, eliciting more facilitation (i.e., national health campaign) but less harm (i.e., fighting animals). Stereotypically competent (vs. incompetent) animals matched with passive scenarios, eliciting more facilitation (i.e., restricted areas) but less harm (i.e., accidental mortality). Accordingly, stereotypes limited the suitability of scenarios toward animals. Although findings are consistent with the SCM/BIAS map framework, several unpredicted results emerged. The mixed support is discussed in detail, along with the implications of an intergroup approach to animals.

Lexicon and Scenarios of Touch Perception: Towards Developing a Research Thesaurus

The paper shows the important advance in sensory neuroscience achieved with a recent discovery of C-tactile system integrating mechanosensitive C fibers that innervate the hairy skin and representing the neurobiological substrate for the affective and rewarding properties of touch. It has drawn scientists' attention to social touch research and has increased the demand for developing psychometric instruments of touch perception assessment calling for developing an elaborated and cross-culturally validated touch lexicon. The paper focuses on creating a Russian touch lexicon and assessing the relevance of different sensory and emotional characteristics (a list of 270 adjectives and participles) to active ('I touch', 80 participants) and passive ('I am being touched', 75 participants) scenarios of touch perception by native speakers of the Russian language. A comparison to previously reported data for the sample of American English speakers has revealed a general similarity of Russian and English touch lexicons. Active touch perception scenario was characterized by the dominance of haptic characteristics (features relevant to sensory properties of objects), while in passive touch perception scenario a prominent increase was observed for the perceived relevance of touch recipient's sensory experience characteristics including words related to pain, tickle, chafing, and itch. The results suggest that the choice of particular words used in task descriptions and in semantic differential scales should be made relevant to the particular touch perception scenarios, rather than relying on a limited generic touch lexicon.

A Mixed-Methods Investigation Into the Acceptability, Usability, and Perceived Effectiveness of Active and Passive Virtual Reality Scenarios in Managing Pain Under Experimental Conditions

Burn patients often suffer excruciating pain during clinical procedures, even with analgesia. Virtual Reality (VR) as an adjunct to pharmacological therapy has proved promising in the management of burn pain. More evidence is needed regarding specific forms of VR. This mixed-method study examined the impact of active and passive VR scenarios in experimental conditions, gathering data relating to user experience, acceptability, and effectiveness in managing pain. Four scenarios were developed or selected following a consultative workshop with burn survivors and clinicians. Each was trialed using a cold pressor test with 15 University students. Data were gathered regarding pain threshold and tolerance at baseline and during each exposure. Short interviews were conducted afterwards. The two active scenarios were ranked highest and significantly extended participants' pain threshold and tolerance times compared to passive and baseline conditions. Passive scenarios offered little distraction and relief from pain. Active scenarios were perceived to be engaging, challenging, distracting, and immersive. They reduced subjective awareness of pain, though suggestions were made for further improvements. Results suggested that active VR was acceptable and enjoyable as a means of helping to control experimental pain. Following suggested improvements, scenarios should now be tested in the clinical environment.

Ambiguity Function Analysis for OFDM-Based LDACS Passive Multistatic Radar

The ambiguity function analysis is central to investigating the resolution capabilities of a radar system. It is particularly important for passive radar scenarios, where the signals of opportunity have not been originally designed for radar purposes. This paper focuses on studying the achievable resolution capabilities for a noncoherent orthogonal frequency division-multiplexing (OFDM)-based passive multistatic radar for L-band digital aeronautical communication system (LDACS) signals. For this purpose, the ambiguity function obtained when employing the OFDM-based LDACS communications signals as signals of opportunity is studied. A generic bistatic link is considered and closed-form expressions for the expectation of the corresponding ambiguity function when accounting for the different signal contributions are derived. The resulting expressions are then used to evaluate and analyze the overall multistatic radar ambiguity function for two sample radar scenarios. The results highlight the impact of the geometry on the shape of the ambiguity function, allowing therefore for a better understanding of the effect that the geometry has on the range and velocity resolution capabilities of the studied system.

Galaxy and Mass Assembly (GAMA): variation in galaxy structure across the green valley

Using a sample of 472 local Universe (z<0.06) galaxies in the stellar mass range 10.25 < log M*/M_sun < 10.75, we explore the variation in galaxy structure as a function of morphology and galaxy colour. Our sample of galaxies is sub-divided into red, green and blue colour groups and into elliptical and non-elliptical (disk-type) morphologies. Using KiDS and VIKING derived postage stamp images, a group of eight volunteers visually classified bars, rings, morphological lenses, tidal streams, shells and signs of merger activity for all systems. We find a significant surplus of rings ($2.3\sigma$) and lenses ($2.9\sigma$) in disk-type galaxies as they transition across the green valley. Combined, this implies a joint ring/lens green valley surplus significance of $3.3\sigma$ relative to equivalent disk-types within either the blue cloud or the red sequence. We recover a bar fraction of ~44% which remains flat with colour, however, we find that the presence of a bar acts to modulate the incidence of rings and (to a lesser extent) lenses, with rings in barred disk-type galaxies more common by ~20-30 percentage points relative to their unbarred counterparts, regardless of colour. Additionally, green valley disk-type galaxies with a bar exhibit a significant $3.0\sigma$ surplus of lenses relative to their blue/red analogues. The existence of such structures rules out violent transformative events as the primary end-of-life evolutionary mechanism, with a more passive scenario the favoured candidate for the majority of galaxies rapidly transitioning across the green valley.

I Know What You Saw Last Minute—Encrypted HTTP Adaptive Video Streaming Title Classification

Desktops and laptops can be maliciously exploited to violate privacy. There are two main types of attack scenarios: active and passive. In this paper, we consider the passive scenario where the adversary does not interact actively with the device, but he is able to eavesdrop on the network traffic of the device from the network side. Most of the Internet traffic is encrypted and thus passive attacks are challenging. Previous research has shown that information can be extracted from encrypted multimedia streams. This includes video title classification of non HTTP adaptive streams (non-HAS). This paper presents an algorithm for encrypted HTTP adaptive video streaming title classification. We show that an external attacker can identify the video title from video HTTP adaptive streams (HAS) sites such as YouTube. To the best of our knowledge, this is the first work that shows this. We provide a large data set of 10000 YouTube video streams of 100 popular video titles (each title downloaded 100 times) as examples for this task. The dataset was collected under real-world network conditions. We present several machine algorithms for the task and run a through set of experiments, which shows that our classification accuracy is more than 95%. We also show that our algorithms are able to classify video titles that are not in the training set as unknown and some of the algorithms are also able to eliminate false prediction of video titles and instead report unknown. Finally, we evaluate our algorithms robustness to delays and packet losses at test time and show that a solution that uses SVM is the most robust against these changes given enough training data. We provide the dataset and the crawler for future research.

Depositional age, provenance characteristics and tectonic setting of the Meso- and Neoproterozoic sequences in SE Yangtze Block, China: Implications on Proterozoic supercontinent reconstructions

Meso- to Neoproterozoic sedimentary successions along the southeastern margin of the Yangtze Block in South China have been investigated for their depositional ages, provenance and tectonic setting. The 1524 Ma, 834 Ma and 763 Ma U-Pb ages of detrital zircons for here investigated Tianli Schists, Liuyuan and Wengjialing sandstone constrain the maximum depositional ages for the respective sedimentary protoliths. Considerable time lag between onset of sedimentation and the age of source rocks suggests that the sedimentary protolith of the Tianli Schists received detritus from a wide range of cratonic sources in a tectonically passive scenario, as indicated by their elevated Zr/Sc ratios. Extraneous source for the 2700–2600 Ma detritus indicates that the sedimentary protolith for the Tianli Schists itself was deposited in a basin that received detritus from the Yangtze Block during the fragmentation of the Columbia/Nuna supercontinent. On the other hand, profuse syn-sedimentary magmatic (804–849 Ma) detritus for the Liuyuan sandstone indicates a continental arc setting, also supported by the La-Th-Sc and Th-Co-Zr signatures. The Wengjialing Formation and its equivalents were deposited in a continental rift basin, coeval with the breakup of Rodinia supercontinent, with addition of newly formed arc-related rocks (≥820 Ma) and syn-rifting magmatic rocks (810–760 Ma) as the predominant sources. These features provide substantial evidence for the paleogoegraphic reconstructions of the southeastern Yangtze Block within the Proterozoic supercontinent configurations.

On the security of cooperative cognitive radio networks with distributed beamforming

This paper investigates the secrecy performance of amplify-and-forward (AF)-relaying cooperative cognitive radio networks (CCRNs) over Rayleigh-fading channels. Specifically, we consider practical passive eavesdropping scenarios, where the channel state information of the eavesdropper’s link is not available at the secondary transmitter. In order to avoid interfering with the primary receiver and enhance the secrecy performance, collaborative distributed beamforming is adopted at the secondary relays. Closed-form and asymptotic expressions for the secrecy outage probability of CCRNs in the presence of single and multiple non-colluding eavesdroppers are derived. The asymptotic analysis reveals that the achievable secrecy diversity order of collaborative distributed beamforming with M AF relays is M−1 regardless of the number of eavesdroppers. In addition, simulations are conducted to validate the accuracy of our analytical results.