Passive Detection Research Articles

A Combined Passive Automatic Detection Method of Constant False Alarms and Multiple Nodes

Aiming at the problem of whether multi-array passive joint detection can improve the detection performance of sonar, this paper analyzes in detail the relationship between the detection probability, false alarm probability, the input signal-to-noise ratio, and integration time under the condition of single array detection, and then obtains the input signal-to-noise ratio and integration time required to achieve the same detection probability and false alarm probability under different joint detection rules. It is concluded that the multi-array joint detection can reduce the required input signal-to-noise ratio and integration time and provide detection performance, which is verified by simulation experiments.

A novel CSoDoA based passive islanding detection technique for multi‐DER AC microgrid control

AbstractMicro‐grid islanding methods are gaining importance as the presence of renewable energy resources is becoming increasingly popular in power distribution. Among all the islanding methods, passive methods are easy to implement and applicable to all types of DERs provided the NDZ is minimized. This article presents a novel passive islanding detection method based on the CSoDoA of ellipse formed by the successive phase voltages to address the NDZ problem. The peak magnitude and phase angle difference of voltages are the parameters to be estimated to compute the area of the ellipse. State‐of‐the‐art passive methods consider the effect of either magnitude or phase angle or frequency as an islanding detection metric. The CSoDoA metric combines the effect of both magnitude and phase angle thereby reducing the NDZ. The proposed method is validated on both synchronous and inverter‐interfaced DERs. The test systems considered are both single‐DER based MG and modified IEEE 13 bus multi‐DER MG. The CSoDoA algorithm is implemented on a Raspberry‐Pi controller and validated using HIL workbench with real‐time simulator OP‐4510. Various islanding and non‐islanding events are simulated, tested and it is evident from the results that it has a very small NDZ.

Advances in Marine Intelligent Electromagnetic Detection System, Technology, and Applications: A Review

This paper introduces the current state of the art in marine intelligent electromagnetic detection sensors, systems and platforms for the detection and health monitoring of offshore structures, especially for subsea cables and pipelines. The presented survey is by no means exhaustive, but introduce some notable results and relevant techniques in the detection and inspection of marine structure electromagnetic monitoring fields. Particularly, this paper presents a review of the main research works focusing on electromagnetic detection techniques and intelligent marine vehicles for subsea cables. The marine electromagnetic exploration techniques are elaborated as active and passive detections based on different electromagnetic field generation and sensing principles. The pulse induction-based detection method for subsea ferromagnetic lines detection, transient and controlled-source electromagnetic systems in marine geological fields under the category of active detection approach, are reviewed. According to the classical applications on subsea cable-like target inspection, the passive detection approach is detailed classified as crisscrossing detection and along-tracking detection, which are characterised by different trajectories of detection vehicles. Finally, the paper discusses the marine electromagnetic detection techniques in general and highlights challenges that need to be addressed in developing detection vehicles with lower electromagnetic noises and advanced autonomy on carrying out detection missions.

Feature-Aided Passive Tracking of Noncooperative Multiple Targets Based on the Underwater Sensor Networks

Passive detection can work for a long time with low energy consumption in underwater surveillance. However, tracking unknown noncooperative targets with only direction angles is challenging, and the tracking performance of multiple targets is poor. Based on several passive sensors in the underwater sensor network (UWSN), a feature-aided state estimation method is used to start tracking unknown targets. The feature-aided joint probabilistic data association combined with the particle filter method is also proposed to improve the passive tracking performance of multiple targets. The track management and the fusion strategy are given to remove fake tracks and obtain correct trajectories of unknown targets. The simulation results show that the feature-aided method can quickly start and effectively track multiple noncooperative targets with passive sensors. Compared with other methods, the proposed method can track targets more accurately with the advantages of low energy consumption and less exposure in various environments.

Cellular response to photo-mediated ultrasound therapy

Photo-mediated ultrasound therapy (PUT) is a novel technique that combines relatively low-pressure focused ultrasound and low-fluence laser to enhance cavitation inside blood vessels. Due to the increased shear and circumferential stresses, the enhanced cavitation activity can achieve anti-vascular effect. The role of endothelial cells in the antivascular effect of PUT was explored by quantifying the release of vasodilators-nitric oxide and prostacyclin from endothelial cells after PUT, laser-only, and ultrasound-only therapies in an in vitro vessel mode. PUT was able to suppress both the vasodilators by more than 5% with concurrently applied 0.5MPa ultrasound pressure at 500 kHz and 15 mJ/cm2 laser fluence at 532 nm. Both the laser-only and ultrasound-only therapies at the similar levels resulted only in elevation of these vasodilators with respect to control. The suppression of vasodilators by PUT was justified with cavitation signals observed using passive cavitation detection and apoptosis observed with Annexin V-fluorescein isothiocyante (FITC), at respective levels. The endothelial cellular response to PUT further motivated us to evaluate the effect of PUT on melanoma cells and evaluate cytotoxic effect through MTT assay. PUT was able to destroy cancer cells through the cavitation effect when compared to laser-only and ultrasound-only therapies at the similar energy levels.

Histotripsy of healthy and tendinopathic ex vivo bovine tendons

Histotripsy has successfully fractionated most soft tissues; however, highly collagenous tissues like tendon have been resistant to histotripsy fractionation. Previously, we showed that some histotripsy parameters could create mild mechanical microdamage in healthy ex vivo rat tendons. Our objective here is to evaluate whether complete histotripsy fractionation is possible in tendons. Eight bovine tendons were injected with collagenase to induce tendinopathy; an additional four tendons were unaltered. Tendons were exposed to single- or dual-frequency histotripsy at 1.07-, 1.5-, and/or 3.68-MHz with 10-ms pulses delivered at 1 Hz for 60 s. Treatments were monitored with passive cavitation detection (PCD) and samples were evaluated for damage. Results show that exposure of tendinopathic tendons to 1.5- and 3.68-MHz dual-frequency histotripsy produces a distinct, fractionated hole; 1.5- and 3.68-MHz single-frequency histotripsy produces partial fractionation without a distinct hole. No fractionation was observed in healthy tendons, or in tendinopathic tendons exposed to 1.07 MHz single- or dual-frequency histotripsy. Histologically, all tendons showed evidence of thermal necrosis independent of whether a hole was observed. PCD showsincreases in amplitude and sustainment of cavitation in exposures that successfully fractionated tendon. These results suggest histotripsy fractionation is possible in tendinopathic tendons. [Work supported by NIH R21EB027886 and R01EB032860.]

Assessment of integrated renewable energy system state through VFMF—A novel approach

Islanding is the most important prerequisite to integrated energy systems, significantly when they are operating with Distributed Generation (DG) or Microgrid (MG) units. In this paper, a novel Variable Fuzzy Membership Function (VFMF) islanding detection is proposed for an inverter based integrated renewable energy system that consists of a either DG or MG units. Passive Islanding Detection (IDT) with Deviations in Frequency (DIF) and Deviations in Voltage (DIV) are the main data sets for the proposed VFMF approach. Proposed method is based on updating of Fuzzy Membership Function (FMF); those are obtained for each Islanding Event (IE) and Non Islanding Event (NIE) of operation. Control vector of a fuzzy system i.e Fuzzy Control Vector (FCV) is used for a range of Misclassification Data of Event (MDOE) either in IE or NIE. VFMF supports for obtaining FCV to achieve proper assessment of IDT in the test system. Handling of DIV/DIF from MDOE, false tripping signal is avoided at every NIE. Effectiveness of proposed method is validated through many IE and NIE cases.

Transcranial cavitation mapping of blood–brain barrier opening regions in Alzheimer’s disease patients using a neuronavigation-guided focused ultrasound system

We present real-time cavitation monitoring and mapping in a clinical trial for blood-brain barrier (BBB) opening in Alzheimer’s disease (AD) patients using a neuronavigation-guided focused ultrasound (FUS) system. Six AD patients (N = 6, age = 68.5 ± 9.5) were sonicated at the right prefrontal lobe with a single-element FUS transducer (PNP = 0.2 MPa, fc = 0.25 MHz, pulse length = 10 ms, PRF = 2 Hz, duration = 2 min) with the microbubble administration (Definity). We performed passive cavitation detection (PCD) using a single-element hydrophone (N = 4), and passive acoustic mapping (PAM) with a 64-element phased array transducer (N = 2). Five patients showed successful BBB opening (volume = 654 ± 394 mm3) on day0, and closure on day3, confirmed by contrast-enhanced T1-weighted MRI, while one patient served as a negative BBB opening case due to the insufficient microbubble administration. Ultra-harmonic cavitation dose (CD) correlated with the opening volume (R2 = 0.66, N = 4), but harmonic and broadband CDs showed a relatively poor correlation (R2 = 0.06 and 0.33). Cavitation maps (N = 2) showed a spatial distribution of acoustic energy that roughly coincided with the respective BBB opening location. We thus demonstrated the successful BBB opening and cavitation monitoring with the neuronavigation-guided system that allowed for a cost-effective procedure compared to the MR-guided approaches. The PCD and PAM showed promising results for potentially predicting the BBB opening volume and location found in MRI.

Real-time transcranial mapping in non-human primates and human subjects during opening of the blood-brain barrier

Opening of the blood-brain barrier (BBB) with focused ultrasound and microbubbles has been shown repeatedly in several preclinical disease models and clinical studies. Transcranial 2D mapping of the cavitation mechanism responsible for BBB opening is however challenging in primate brains due to the skull thickness. A real-time cavitation mapping system will be presented that can transcranially map the cavitation occurrence and dose in real time throughout the BBB opening procedure in Alzheimer’s disease (AD) adult and diffuse intrinsic pontine glioma (DIPG) pediatric patients. Passive acoustic mapping (PAM) with coherence factor (CF) correction is used to passively map the microbubble activity within the brain. Compared to passive cavitation detection (PCD), multi-element CF-PAM allows us to determine the exact location of the BBB opening without the need of contrast-enhanced MRI. An open-architecture ultrasound imager (Vantage, Verasonics, Redmond, WA) with a P4-2 (ATL, Philips) is used to provide the best tradeoff between transcranial propagation, spatial resolution and depth penetration. The system is first optimized in targeting the putamen during BBB opening in non-human primates followed by feasibility in the prefrontal cortex in AD and the pons in DIPG patients, achieving feedback rates of 2 Hz during the clinical procedures.

MRI-guided focused ultrasound drug delivery to DMG tumors in a mouse model

Diffuse midline glioma (DMG) is the most common and unfortunately the most deadly brainstem tumor in childern. Current clincal treatment methods only involve palliative radiotherapy that does not significantly improve survival beyond its poor mean survival of 9 months. These tumors remain difficult to treat with chemotherapy as they maintain an intact blood brain barrier (BBB). Focused ultrasound (FUS) and microbubbles (MBs) has been shown to disrupt the BBB, allowing chemotherapeutics to enter the perenchyma. Panobinostat is one of the chemotherapeutics that has difficulty crossing the BBB, although it has promising effects in vitro. In this study, we hypothesized that MB + FUS could disrupt the BBB, allowing a higher concentration of Panobinostat to enter the tumor region and provide a therapeutic effect. Our results demonstrate that MB + FUS can successfully deliver Panobinostat to the pons with DMG tumors over 3-fold, while only slightly increasing the concentration of the forebrain. Passive cavitation detection during treatments showed harmonic cavitation throughout the 3-minute treatment, while not having any significant broadband cavitation. The combination of both Panobinostat and MB + FUS showed major decreases in tumor growth by ∼71% by the end of the treatment weeks when compared to Panobinostat alone. A significant survival benefit was also demonstrated.

5G PRS-Based Sensing: A Sensing Reference Signal Approach for Joint Sensing and Communication System

The emerging joint sensing and communication (JSC) technology is expected to support new applications and services, such as autonomous driving and extended reality (XR), in the future wireless communication systems. Pilot (or reference) signals in wireless communications usually have good passive detection performance, strong anti-noise capability and good auto-correlation characteristics, hence they bear the potential for applying in radar sensing. In this paper, we investigate how to apply the positioning reference signal (PRS) of the 5th generation (5 G) mobile communications in radar sensing. This approach has the unique benefit of compatibility with the most advanced mobile communication system available so far. Thus, the PRS can be regarded as a sensing reference signal to simultaneously realize the functions of radar sensing, communication and positioning in a convenient manner. Firstly, we propose a PRS based radar sensing scheme and analyze its range and velocity estimation performance, based on which we propose a method that improves the accuracy of velocity estimation by using multiple frames. Furthermore, the Crámer-Rao lower bound (CRLB) of the range and velocity estimation for PRS based radar sensing and the CRLB of the range estimation for PRS based positioning are derived. Our analysis and simulation results demonstrate the feasibility and superiority of PRS over other pilot signals in radar sensing. Finally, some suggestions for the future 5G-Advanced and 6th generation (6 G) frame structure design containing the sensing reference signal are derived based on our study.

Long-term vs. short-term measurements in indoor Rn concentration monitoring: Establishing a procedure for assessing exposure potential (RnEP)

Radon (Rn-222 or Rn) is a naturally occurring chemical element that belongs to the progeny of U-238 released from soil and rocks into the atmosphere, whose impact on organisms is not negligible when it occurs inside confined spaces, such as mine shafts or low-ventilated buildings. The current methodologies for indoor radon assessment are based on passive and active detection. If passive detectors are mainly designed for long-term assessment, active detectors are electronic equipment that can allow on-time visualization of results and, therefore, faster decision-making on risk mitigation measures implementation. However, despite offering a prompt and informed decision, the uncertainty associated with active detector results may cast doubt on the quality of the measurements, which especially arises from the duration of the monitoring campaign. Since radon emanation from soils and rocks depends on a set of variables related to meteorological parameters and soil structure, the seasonal variation of these parameters impacts indoor radon concentration assessment, both on short-term and long-term measurements. Therefore, short-term monitoring campaigns lasting a month, a week, or a day may not produce a statistically representative description of indoor radon exposure for the monitored building. Accordingly, the study compares the reliability of short-term and long-term indoor radon measurements. It proposes a procedure for assessing the indoor Radon Exposure Potential (RnEP) based on in situ measurements through the analysis of the frequency of occurrence of results divided into three classes of potential exposure (low, moderate and high) to reduce occupants' radon risk exposure.

Evaluation of passive microwave dry snow detection algorithms and application to SWE retrieval during seasonal snow accumulation

The microwave emission of snow has distinctive, frequency-dependent characteristics that enable the use of passive microwave remote sensing for the detection of (dry) snow alongside the study of further snow properties. Passive microwave approaches for the retrieval of snow water equivalent (SWE) often implement dry snow detection as one of the main processing steps. Reliable dry snow detection is thus crucial; however, common algorithms tend to underestimate snow cover extent. This study conducts a long-term assessment of six dry snow detection algorithms as part of ongoing GlobSnow SWE product development. We focus on terrestrial snow on the Northern Hemisphere, using exhaustive in situ snow depth measurements and spatially complete snow maps by the NOAA Interactive Multisensor Snow and Ice Mapping System (IMS). In addition to using conventional daily snow masks, cumulative snow masks are investigated as means to counteract underestimation and the results emphasise their potential for this purpose. Best performances are achieved by the cumulative versions of the algorithm of the EUMETSAT H SAF H11 product and of the decision tree by Grody and Basist (1996), which agree with in situ data by approximately 81% and 84% whilst differing from IMS maps by only about 15% and 11%, respectively. Their validation for hemispheric SWE retrieval in the GlobSnow framework, using in situ snow course SWE observations, shows a noticeable improvement of the current statistics especially during shallow snow conditions in autumn—reducing the bias by up to 2.2 mm and the RMSE by up to 2.0 mm. This highlights the impact that the algorithm choice for dry snow detection has on the quality of SWE retrieval and therefore on long-term climate data records.

A note on recordings of Southern right whales (Eubalaena australis) off the coast of Uruguay

Passive acoustic detection has the potential to provide data regarding the location of right whales. Right whales are not known to produce songs; nonetheless, the call repertoire of Eubalaena australis, the southern right whale, has been exhaustively and quantitatively analysed. This paper describes sound production by southern right whales in the coast of Uruguay (35°S) in the South Atlantic Ocean. No previous study of southern right whale sounds in Uruguayan waters exists. The calls recorded were: Up call, a low tonal call with a frequency of 50Hz to 200Hz; High call, which has the most energy in a range of 200–500Hz, and Pulsive call, a complex mixture made up of amplitude modulated noise and tones, 50– 200Hz. This is the first acoustic study of E. australis in this region and focusses on the occurrence of calls previously identified by Clark to obtain more information about the acoustic behaviour of this cetacean in Uruguayan coastal waters. Future efforts will be made to obtain more recordings in different locations along the coast of Uruguay, where annual sightings occur. Such information is essential for examining global differences between vocalisations of southern right whales.

Widespread passive acoustic monitoring reveals spatio-temporal patterns of blue and fin whale song vocalizations in the Northeast Pacific Ocean

The NOAA-NPS Ocean Noise Reference Station Network (NRS) is a passive acoustic monitoring effort to record the low-frequency (<2 kHz) sound field throughout the U.S. Exclusive Economic Zone. Data collection began in 2014 and spans 12 acoustic recording locations. To date, NRS datasets have been analyzed to understand spatial variation of large-scale sound levels, however, assessment of specific sound sources is an area where these datasets can provide additional insights. To understand seasonal patterns of blue whale,Balaenoptera musculus, and fin whale,B. physalus, sound production in the eastern North Pacific Ocean, this study explored data recorded between 2014 and 2020 from four NRS recording sites. A call index (CI) was used to quantify the intensity of blue whale B calls and fin whale 20 Hz pulses. Diel and seasonal patterns were then determined in the context of their migratory patterns. Most sites shared similar patterns in blue whale CI: persistent acoustic presence for 4–5 months starting by August and ending by February with a CI maximum in October or November. Fin whale patterns included persistent acoustic presence for 5–7 months starting by October and ending before April with a CI maximum between October and December. The diel patterning of blue whale song varied across the sites with the Gulf of Alaska, Olympic Coast, Cordell Bank, and Channel Islands (2014–2015) exhibiting a tendency towards nighttime song detection. However, this diel pattern was not observed at Channel Islands (2018–2020). Fin whale song detection was distributed evenly across day and night at most recording sites and months, however, a tendency toward nighttime song detection was observed in Cordell Bank during fall, and Gulf of Alaska and Olympic Coast during spring. Understanding call and migration patterns for blue and fin whales is essential for conservation efforts. By using passive acoustic monitoring and efficient detection methods, such as CI, it is possible to process large amounts of bioacoustic data and better understand the migratory behaviors of endangered marine species.

Decoding the Kodi Ecosystem

Free and open-source media centers are experiencing a boom in popularity for the convenience they offer users seeking to remotely consume digital content. Kodi is today’s most popular home media center, with millions of users worldwide. Kodi’s popularity derives from its ability to centralize the sheer amount of media content available on the Web, both free and copyrighted . Researchers have been hinting at potential security concerns around Kodi, due to add-ons injecting unwanted content as well as user settings linked with security holes. Motivated by these observations, this article conducts the first comprehensive analysis of the Kodi ecosystem: 15,000 Kodi users from 104 countries, 11,000 unique add-ons, and data collected over 9 months. Our work makes three important contributions. Our first contribution is that we build “crawling” software ( de-Kodi ) which can automatically install a Kodi add-on, explore its menu, and locate (video) content. This is challenging for two main reasons. First, Kodi largely relies on visual information and user input which intrinsically complicates automation. Second, the potential sheer size of this ecosystem (i.e., the number of available add-ons) requires a highly scalable crawling solution. Our second contribution is that we develop a solution to discover Kodi add-ons. Our solution combines Web crawling of popular websites where Kodi add-ons are published (LazyKodi and GitHub) and SafeKodi , a Kodi add-on we have developed which leverages the help of Kodi users to learn which add-ons are used in the wild and, in return, offers information about how safe these add-ons are, e.g., do they track user activity or contact sketchy URLs/IP addresses. Our third contribution is a classifier to passively detect Kodi traffic and add-on usage in the wild. Our analysis of the Kodi ecosystem reveals the following findings. We find that most installed add-ons are unofficial but safe to use. Still, 78% of the users have installed at least one unsafe add-on, and even worse, such add-ons are among the most popular. In response to the information offered by SafeKodi, one-third of the users reacted by disabling some of their add-ons. However, the majority of users ignored our warnings for several months attracted by the content such unsafe add-ons have to offer. Last but not least, we show that Kodi’s auto-update, a feature active for 97.6% of SafeKodi users, makes Kodi users easily identifiable by their ISPs. While passively identifying which Kodi add-on is in use is, as expected, much harder, we also find that many unofficial add-ons do not use HTTPS yet, making their passive detection straightforward. 1

Passive Directivity Detection Using Individual Biaxial Ultrasound Transducers.

Biaxial transducers are an emerging technology that can steer generated ultrasound waves using a single piezoceramic component. Simulations have also shown that biaxial transducers can passively estimate the direction of arrival (DOA) of sound waves when operating in the receive mode. This research seeks to experimentally verify biaxial directivity estimates and establish directivity as an independent parameter detected by biaxial transducers. Three cuboid ( 3.84×3.84×5.92 mm) biaxial piezoceramics with two pairs of orthogonal electrodes (one pair applied laterally and one pair applied in the polling direction) were manufactured and characterized. Each transducer was placed in a water tank where an independent hemispherical source was attached to a moveable arm and operated at 250 kHz. Terminal voltages were recorded for 81 source positions in a plane parallel to the transducer's front face and at a depth of approximately 9 cm. Collection was repeated three times per transducer to ensure reproducibility. In silico results were compared with the experimental results. Two derived metrics were then calculated using both the forward and lateral terminal voltages: the phase difference and amplitude ratio. Biaxial transducers demonstrate an ability to estimate the DOA of incident sound waves, independently of any time-of-flight (TOF) information. The phase difference and amplitude ratio complement each other to provide statistically significant and repeatable estimates over a range of 48° (from -24° to +24°). These results can be used to augment a variety of medical, geophysical, and industrial passive ultrasound imaging techniques.

Development of a cryogenic passive-scattering-type near-field optical microscopy system.

Passive scattering-type, scanning near-field optical microscopy (s-SNOM) has been employed to study localized, long-wavelength infrared (LWIR) surface waves without external illumination. Here, we develop a cryogenic passive s-SNOM instrument in a vacuum chamber with 4K liquid-helium cooling. Notably, the extremely low-temperature environment inside the chamber enables the realization of passive near-field detection with low background thermal noise. The technique mainly utilizes a highly sensitive LWIR confocal optical system and a tuning fork-based atomic force microscope, and the near-field detection was performed at a wavelength of 10.2 ± 0.9 µm. In this paper, we discuss the cryogenic s-SNOM implementation in detail and report the investigation of thermally excited surface electromagnetic fields on a self-heated NiCr wire deposited on SiO2 at a temperature of 5K. The origin of the surface electromagnetic fields was established to be the thermally excited fluctuating charges of the conduction electrons. The cryogenic s-SNOM method presented herein shows significant promise for application in a variety of spheres, including hot-carrier dissipation in ballistic conductors.

Single-molecule force manipulation facilitated multiple rereads of a drug-bound DNA at specified sites by surface-enhanced Raman spectroscopy.

Single-molecule surface-enhanced Raman spectroscopy (SERS) directly probes the vibrational characteristics of individual molecules to uncover the information inaccessible from ensemble measurements. As a surface-sensitive technique, the amplification of SERS signal occurs upon the excitation of localized surface plasmon resonance in metallic nanostructures, which can overcome optical diffraction limit for spatial detections at a nanometer scale. Complementary to this passive detection technique, optical tweezers-based single-molecule force manipulation method enables the active control of a target molecule with the restricted orientation in three dimensions. By applying a stretching force to the target molecule, it provides high-frequency feedback in sub-milliseconds with sub-piconewton force resolution and sub-nanometer distance sensitivity. Combining the active molecular control and the passive molecular vibrational measurement, we have integrated the dual-traps optical tweezers technique with the Raman spectroscopic detection platform. Under precise single-molecule force manipulations, the real-time SERS readout of the specified sites of a drug-bound DNA are recorded and re-recorded multiple times in a programmable manner. Our results showcase the promise of this correlative molecular manipulation and detection approach for real-time, label-free, and multi-dimensional characterizations of a single target biomacromolecule with both high spatial resolution and high site-specified recognition accuracy.

Indonesian Cryptocurrencies Legislative Readiness: Lessons from the United States

Cryptocurrencies can facilitate cross-border global transfers easily and pseudonymously. It can be converted into fiat currencies, making it suitable for money laundering crimes. This study compared legal regulations in the United States that analysed the readiness of regulations and Indonesia's legal loopholes in responding to the development of the cryptocurrency business. As a result, cryptocurrency in Indonesia is susceptible to being used as a money-laundering tool due to the novelty of the technology, the anonymity it provides its users, and the immaturity of the regulations governing it. Therefore, it is necessary to create a cryptocurrency that can follow the “Travel Rule” and collect and share information about the people who send and receive cryptocurrency, like in the US. The study also argues that passive detection is used to detect the identity of cryptocurrency users through a centralised service. However, several cryptocurrency developers have responded to the increase in pseudonymity tracking methods by developing cryptocurrencies with greater secrecy change.