Large Fin Research Articles

Numerical study of the effect of winglet on the aerodynamic performance of sinusoidal and simple leading-edge wings

PurposeThis study aims to investigate the effectiveness of two types of winglets, multi-tip and raked, on the performance of sinusoidal and simple leading-edge wings and compares it by a numerical method.Design/methodology/approachThe wing configuration in this study is rectangular and uses NACA0020 section, and all simulations are performed by a numerical method based on finite volume and base pressure algorithm in Reynolds 2 × [10]^5. In the mentioned numerical method, the flow is considered turbulent, and the k-ω-SST model is used. To calculate the stresses on the wing surface, the mesh is extended to below the viscous layer, and a second-order upstream accuracy is used to calculate the convection flux.FindingsThe use of raked and multi-tip winglets for the sinusoidal edge of the wing improved aerodynamic performance by 5.12 and 2.28%, respectively, and the greatest effect of these two winglets was on increasing the lifting force and reducing the inductive drag, respectively. Also, by examining the distribution of induced vortices around the configurations, it was found that the curvature of the sinusoidal wing tip at the angles of attack before stall reduced the strength of the induced vortices and, the use of winglet during and after stall, caused increased aerodynamic performance of the sinusoidal wing.Practical implicationsThe whale is an international species of aquatic animal found in most of the world’s oceans. It has large fin aspect ratios that have a series of bulges at the edge of the attack, which improves the aerodynamic performance near and after stall. Today, one of the fields of research is the use of this idea in the wings of micro air vehicle.Originality/valueWinglet reduces induced drag in simple wings. So far, the effect of winglets on wings with sinusoidal attack edges has not been investigated.

Return of large fin whale feeding aggregations to historical whaling grounds in the Southern Ocean

Fin whales (Balaenoptera physalus quoyi) of the Southern Hemisphere were brought to near extinction by twentieth century industrial whaling. For decades, they had all but disappeared from previously highly frequented feeding grounds in Antarctic waters. Our dedicated surveys now confirm their return to ancestral feeding grounds, gathering at the Antarctic Peninsula in large aggregations to feed. We report on the results of an abundance survey and present the first scientific documentation of large fin whale feeding aggregations at Elephant Island, Antarctica, including the first ever video documentation. We interpret high densities, re-establishment of historical behaviours and the return to ancestral feeding grounds as signs for a recovering population. Recovery of a large whale population has the potential to augment primary productivity at their feeding grounds through the effects of nutrient recycling, known as 'the whale pump'. The recovery of fin whales in that area could thus restore ecosystem functions crucial for atmospheric carbon regulation in the world's most important ocean region for the uptake of anthropogenic CO2.

Experimental research on refrigerant condensation heat transfer and pressure drop characteristics in the horizontal microfin tubes

The condensation heat transfer characteristics and pressure drop for R410A were investigated in the horizontal smooth and microfin tubes. The 6.35-mm-OD, 7-mm-OD and 8-mm-OD tubes with active length 2 m were selected for condensation test cooled by the heat transfer fluid (water) circulated in a surrounding annulus. A refrigerant superheating 2–3 °C was set at the test section inlet and the mass flux range was 300–1100 kg·m−2·s−1. The heat transfer coefficient (HTC) of the microfin tube was about 1.63–2.29 times of that of the smooth one. The microfin one yields ~28.9% higher pressure drop than the smooth one. Large helix angle and fin height were beneficial to enhance heat transfer due to the centrifugal force and surface tension, but increased the pressure drop. 6.35-mm-OD tube produced both the higher HTC and pressure drop than the 7-mm-OD and 8-mm-OD tubes due to the increased effect of the surface tension and the sheer stress at the gas-liquid interface. It was necessary to optimize finned structure to enhance heat transfer. Experimental data were also compared with previous correlations proposed for smooth and microfin tube. It was necessary to collect more data source and make a generally-accepted and accurate correlation in future.

Wire-wrapped and helically-finned tubular ceramic membranes for enhancing water and waste heat recovery from wet flue gas

Recycling water and waste heat from wet flue gas is crucial for sustainable energy-water-environment nexus in industrial processes. Herein, we report the use of wire-wrapped and helically-finned tubular ceramic membranes to construct membrane condensers for simultaneous water and heat recovery. Compared with conventional plain tubular ceramic membrane (PTCM), wire-wrapped tubular ceramic membrane (WTCM) and helically-finned tubular ceramic membrane (FTCM) both exhibit superior water and heat recovery performance, indicating a non-negligible effect of chaotic fluid mixing on heat and mass transfer enhancement. FTCM shows better condensate capture performance than WTCM. Moreover, improved condensing heat transfer performances are observed on FTCMs provided with large fin height and pitch. FTCM provides higher heat transfer coefficients than PTCM at around 7.4% to 59.3% depending on different fin structures. Effects of operation parameters on membrane condensation process using FTCM are also investigated. Gas-side parameters have significant effects on water/heat recovery performance than water-side parameters. This study can serve as a basis for process intensification of membrane-based condensation used for flue gas dehumidification.

Analisis performansi kolektor surya pelat datar dengan diameter lubang sirip berbeda sebagai impinging jet

Solar collector is a device that is able to absorb and transfer heat from solar energy to the working fluid. Solar collectors in general, use a mass flow rate of air that is parallel to the absorbent plate, the air entering the inlet will pass through the absorbent plate and exit directly through the outlet. To improve the performance of the solar collector, modifications were made, namely by adding perforated fins with various hole diameters. The hollow fin is intended as a place for hot fluid to flow in the collector. The solar collector used in this study is a flat plate solar collector. The workings of the solar collector itself is that solar radiation is absorbed by the absorber plate and then transferred to the fluid flowing in the pipe above the absorber plate. The intended diameter modification is to make the hole diameters vary from a large diameter near the inlet to a small diameter near the outlet and from a small diameter near the inlet to a large diameter near the outlet which is installed in parallel. Variations in the diameter of the fin holes are 90mm, 70mm, 50mm, 30mm and 10mm while the placement of the perforated fins is done alternately, from large to small diameter and vice versa. The performance obtained is for useful energy from large to small diameter of 108.71 W while from small to large fin diameter 62.23 W. For efficiency it is obtained 22.62% for variations from large to small diameter and 12.38% for small to large variations.

Parametric CFD study for finding the optimal tube arrangement of a fin-and-tube heat exchanger with plain fins in a marine environment

In the past, fin-and tube heat exchanger (FTHE) tube pattern ratios have been largely based on ad-hoc design principles. Here, we investigate the optimal tube arrangements for a FTHE with plain fins in marine environments represented by two different air types; one for unfiltered air with high condensation rate and one for clean dry filtered air conditions. The thermal-hydraulic efficiency of the FTHE design is measured by comparing a modified ratio of Colburn j-factor and Fanning friction factor. The regression model generated from the CFD data is then used to identify the maximum efficiency for two design specific fin pitches separately. We identified two optimal tube patterns: one for a large fin pitch for unfiltered air, and another for a small fin pitch for filtered air. Manufacturing restrictions were found to significantly limit the maximum achievable efficiency of a tube pattern. By neglecting the related manufacturing restrictions, 4 % higher efficiency for a fin pitch of 1.5 mm and 23 % higher efficiency for a fin pitch of 3.5 mm is achieved. Without any application specific limitations or manufacturing restrictions the fin pitch 1.5 mm can have a 36 % increased efficiency than fin pitch 3.5 mm. These novel results show that development in manufacturing have potential for significant improvements in thermal-hydraulic efficiency. • Fin-and-tube heat exchanger is studied with open source conjugate CFD models. • The smaller fin pitch F p = 1 . 5 mm offers better JF performance than the F p = 3 . 5 mm. • A higher JF performance can be achieved by neglecting the manufacturing restrictions. • Unconventional tube arrangement ratio values P t / P l ≠ 1 . 1547 offer the best JF performance.

Resource partitioning among freshwater congeneric fishes (Loricariidae: Hypostomus): trophic, spatial, and temporal dimensions

ABSTRACT Resource partitioning is essential for coexistence of phylogenetically related species in altered environments, where changes in biotopes can limit resources and change ecological strategies. We investigated resource partitioning between two congeneric catfishes (Hypostomus affinis and H. luetkeni) in three niche dimensions (trophic, spatial, and temporal) in a Neotropical reservoir. We tested the hypothesis that the use of different mesohabitats (spatial dimension) is more relevant for the coexistence of species, and that morphological differences between the species confer different advantages in the mesohabitats occupation. We evaluated species morphology, diet composition and abundance along a spatial-temporal gradient. A high dietary overlap and a low temporal variability in species abundance were found, indicating that these two dimensions play a minor role in the species distribution. However, a strong spatial segregation modulated apparently by morphological differences was observed. Hypostomus luetkeni has a larger oral disk area, and a flatter body that confer advantages in the occupation of lotics habitats, whereas H. affinis has relatively larger fins that provide more efficient displacements in lentic habitats. Spatial partitioning was the main driver modulating mechanism for the coexistence of these species and differences in the occupation of the mesohabitats probably have been amplified in this altered environment.

Digest: More than just a pretty fin: The evolution of sexual ornaments in killifish.

What conditions favor the evolution of elaborate sexual ornaments? In freshwater killifishes, Sowersby etal. found that larger sexual ornaments were negatively associated with locomotive performance. Although selection clearly favored large ornamental fins in environments with fewer predators, there was no clear association between large ornamental fins and differences in life-history strategy. This finding illustrates that habitat differences in predation risk have the potential to influence the evolution of secondary sexual traits such as ornaments through natural selection.

ANALISIS UNJUK KERJA KOLEKTOR SURYA PELAT DATAR DENGAN PENAMBAHAN SIRIP BERLUBANG BERDIAMETER BEDA SEBAGAI NOSEL YANG DISUSUN SECARA STAGGERED

The solar collector is a device that collects solar radiation and converts it into useful heatenergy. Several types of solar collectors include the parallel flow flat plate solar collector and theperpendicular flow absorber plate solar collector. Previous design of flat plate solar collectorperpendicular flow absorber plate usually uses plates with the same hole diameter. To improve theperformance of this solar collector, modifications have been made by adding perforated fins withdifferent diameters which are arranged staggeredly as an air flow channel or nozzle. The intendedmodification of nozzle diameter is to make the nozzle diameter size different from the large diameter nearthe inlet to the small diameter near the oulet and compared to the reverse nozzle position. Making thediameter of the nozzle near the inlet is larger than the diameter of the hole near the outlet aims to makethe mass flow of air passing through the hole near the inlet larger, so that the flow of air massesexperiences more heat transfer while the diameter of the hole near the outlet is made small is to reducethe mass flow of air which is wasted faster through the outlet channel. With the variation of the holediameter from large to small, it is expected that the heat transfer that occurs in the solar collector will bemore optimal, but it should also be seen in the reverse position. The research was carried outexperimentally. The results of his research show that the useful energy and efficiency of solar collectorswith large to small diameter slotted fins are higher than those with small to large diameter slotted fins.

Experimental study on fast quenching of cryogenic LN2 flow through interior micro-fin tube

Future cryogenic vehicle requires a fast propellant fueling as well as a rapid pipeline quenching operation. In the present study, a novel interior micro-fin tube concept, with a series of cyclic fins arranged along the flow direction and has the size of 1 mm in both of fin height and fin width, is proposed to reach the purpose of cryogenic quenching acceleration. A cryogenic quenching test platform is established to evaluate the micro-fin effect. A straight tube and three micro-fin tubes, with fin intervals of 50, 100, and 200 mm, are fabricated and tested under different inlet Reynolds numbers (Re) conditions. The tube quenching cases covering inlet flow rate range of Re = 5000–45,000 are performed, and the results on temperature decrease, heat flux, and pressure drop are analyzed and compared. The test results demonstrate that the proposed micro-fin tube significantly reduces time cost in quenching process, and about 33–62% of time savings are reached for different Re conditions. The mechanism of micro-fin tube in facilitating quenching progress is that a radial velocity component within the annular vapor film could be induced by the micro-fin structure. This radial velocity acts on the liquid-vapor interface directly, which motivates interface fluctuation or tears the interface, and finally brings about an earlier liquid-wall contact at higher wall temperature. Moreover, it shows high heat flux appears immediately at the beginning of the quenching operation, and an approximately linear temperature decrease is experienced throughout the entire process. In addition, changing fin interval could affect the quenching rate under low Re conditions, but the fin interval influence decreases with the increase of Re. The test results show that the fin interval has slight influence on time cost when Re = 30,000. For a high-Re quenching event, a micro-fin tube with large fin interval could be suggested in the view of balancing consideration on heat transfer enhancement and flow resistance reduction. Compared to the surface treatment approaches, the proposed micro-fin structure tube provides a competitive approach in accelerating the quenching progress, and more work should be performed to optimize the micro-fin structure and the fin arrangement.

Cartilage structure increases swimming efficiency of underwater robots

Underwater robots are useful for exploring valuable resources and marine life. Traditional underwater robots use screw propellers, which may be harmful to marine life. In contrast, robots that incorporate the swimming principles, morphologies, and softness of aquatic animals are expected to be more adaptable to the surrounding environment. Rajiform is one of the swimming forms observed in nature, which swims by generating the traveling waves on flat large pectoral fins. From an anatomical point of view, Rajiform fins consist of cartilage structures encapsulated in soft tissue, thereby realizing anisotropic stiffness. We hypothesized that such anisotropy is responsible for the generation of traveling waves that enable a highly efficient swimming. We validate our hypothesis through the development of a stingray robot made of silicone-based cartilages and soft tissue. For comparison, we fabricate a robot without cartilages, as well as the one combining soft tissue and cartilage materials. The fabricated robots are tested to clarify their stiffness and swimming performance. The results show that inclusion of cartilage structure in the robot fins increases the swimming efficiency. It is suggested that arrangement and distribution of soft and hard areas inside the body structure is a key factor to realize high-performance soft underwater robots.

Heat transfer enhancement when boiling on finned surfaces

In this work, we studied the effect of radial surface finning and hydrophobic fluoropolymer coating of finned surfaces on the intensity of heat transfer at boiling. Two samples were used: 16 fins and 32 fins. At first, experiments were carried out without a hydrophobic coating. After that, the samples were covered with a layer of fluoropolymer and a series of experiments were carried out. During these experiments, the state of the fluoropolymer coating was analyzed. Experiments on a sample with 16 fins showed that deposition of fluoropolymer leads to significant intensification of heat transfer. For the sample with 32 fins, the opposite effect was observed: hydrophobization negatively affected the efficiency of heat transfer. Maximal enhancement of heat transfer, in comparison with finely finned and smooth surfaces, was achieved on a surface with large fins coated with fluoropolymer.

Molecular analyses of confiscated shark fins reveal shortcomings of CITES implementations in Germany

AbstractA three‐ton shipment of dry shark fins was examined by German customs in 2017 leading to the confiscation of 405 kg of potential CITES species. We analyzed a subsample of this material (115 specimens) using DNA sequence‐based identification and compared results to morphological screening of CITES species. We found a mixture of CITES regulated (4 of 11 species) and unregulated shark species. Our results demonstrate the difficulties of identifying CITES species morphologically in large fin shipments of mixed species composition. Correct identification of CITES species based on morphology alone may be hindered by missing characters or those altered by drying. We therefore suggest random molecular screening as a uniform approach for German customs authorities to check species composition and identify CITES regulated species in transit shipments.

Thermo-Hydraulic Performance of Square Micro Pin Fins under Forced Convection

Thermal management of the new generation’s high performance electronic and mechanical devices is becoming important due to their miniaturization. Conventionally, the plate fin arrangement is widely used for removal of dissipated heat but, their effectiveness is not up to mark. Among different options, the most attractive and efficient alternative for overcoming this problem is micro pin fin heat sink. This paper presents the experimental investigation of square micro-pin fins heat sink for identifying the most suitable pin fin geometry for heat removal applications under forced convection. Twenty five square micro pin fin heat sinks were tested for three different heat load and Reynolds number. The results show that for large fin height lower thermal resistance was observed at the cost of large pressure drop. The dimensionless heat transfer coefficient increases with fin height and Reynolds number while it decreases with increasing fin spacing. The improvement in micro pin fin efficiency were observed by about 2 to 9% owing to presence of fins on the impingement surface, flow mixing, disruption of the boundary layers, and augmentation of turbulent transport.

Multiple observations of Bigfin Squid (Magnapinna sp.) in the Great Australian Bight reveal distribution patterns, morphological characteristics, and rarely seen behaviour.

One of the most remarkable groups of deep-sea squids is the Magnapinnidae, known for their large fins and strikingly long arm and tentacle filaments. Little is known of their biology and ecology as most specimens are damaged and juvenile, and in-situ sightings are sparse, numbering around a dozen globally. As part of a recent large-scale research programme in the Great Australian Bight, Remotely Operated Vehicles and a towed camera system were deployed in depths of 946–3258 m resulting in five Magnapinna sp. sightings. These represent the first records of Bigfin Squid in Australian waters, and more than double the known records from the southern hemisphere, bolstering a hypothesis of cosmopolitan distribution. As most previous observations have been of single Magnapinna squid these multiple sightings have been quite revealing, being found in close spatial and temporal proximity of each other. Morphological differences indicate each sighting is of an individual rather than multiple sightings of the same squid. In terms of morphology, previous in-situ measurements have been roughly based on nearby objects of known size, but this study used paired lasers visible on the body of a Magnapinna squid, providing a more accurate scaling of size. Squid of a juvenile size were also recorded and are confirmed to possess the long distal filaments which have thus far been mostly missing from specimens due to damage. We have described fine-scale habitat, in-situ colouration, and behavioural components including a horizontal example of the ‘elbow’ pose, and coiling of distal filaments: a behaviour not previously seen in squid. These sightings add to our knowledge of this elusive and intriguing genus, and reinforce the value of imagery as a tool in deep-sea squid research.

Physiological insights for aquaculture diversification: Swimming capacity and efficiency, and metabolic scope for activity in cojinoba Seriolella violacea

Aquaculture diversification is important for providing sustainable sources of food fish amidst changing environments, pathogens, economies, and market demand. Particularly for newly cultured species where information may be limited, optimization of culture practices relies on an understanding of the physiology and ecology of a species. The cojinoba (Seriolella violacea; Centrolophidae), a coastal pelagic marine fish, is a species of growing importance for aquaculture production in South America. Although methods for breeding and larval to juvenile rearing have been established, little is known about the physiology of this species. Therefore, measures of metabolism, swimming capacity and efficiency, red:white (R:W) muscle ratios, and associated aerobic and anaerobic biochemical parameters, such as plasma glucose and lactate, and muscle enzyme activities (i.e., pyruvate kinase, citrate synthase, electron transport system [ETS]), were measured. For cojinoba at 15 °C with mean body length (BL; total length) of 22 cm, critical swimming velocity (Ucrit) was approximately 80 cm/s or 3.8 BL/s, and optimal swimming velocity (Uopt) was 50 cm/s or 2.3 BL/s. Aerobic scope for metabolism was approximately 300 mg O2/kg/h, with Mo2 max 3.4 fold greater than standard metabolic rate. Swimming was facilitated by linear increases in tail beat frequency until burst and glide swimming initiated near Ucrit. At low velocities, large (~20% BL) pectoral fins were used for propulsion and maneuverability/maintaining equilibrium; beat frequency diminished rapidly with increasing velocity. Red:white muscle ratios at 50% BL and 75% BL (caudal peduncle) were comparable to other ectothermic species, with a greater proportion of red muscle in the caudal peduncle presumably corresponding to facilitation of sustained pelagic swimming. Plasma glucose and lactate were elevated at Ucrit by 20% and 45% respectively, indicating mobilization of anaerobic energy sources at fatigue. Aerobic enzyme activities were much higher in red muscle, the ratio of anaerobic:aerobic enzyme activity was higher in white muscle, and ETS activities decreased at fatigue in both red and white muscle. The cojinoba has a moderate metabolic rate compared to other pelagic species, displays shoaling behavior, is maneuverable at low velocities due to pectoral fin use, but has optimal swimming efficiencies at higher velocities. These factors are beneficial for designing culture systems to promote exercise benefits for growth and welfare.

Relative contribution to the shark fin trade of Indo‐Pacific and Eastern Pacific pelagic thresher sharks

AbstractFins from highly mobile shark species entering large shark fin trade hubs can originate from various geographical locations and stocks. Tracing fins from internationally regulated species to their starting point in the supply chain can have important implications for the monitoring and enforcement of international laws intended to protect threatened shark species. Here we use pelagic thresher shark Alopias pelagicus fin samples (N = 86) collected during a 4‐year period (2014–2017), and phylogenetic analyses, using the cytochrome oxidase I (COI), to determine the relative contribution of this species to the two largest shark fin trade hubs in the world, Hong Kong and Guangzhou, mainland China. Our results suggest that the Eastern Pacific is a major starting point of the international supply chain of pelagic thresher shark fins, contributing 84.9% of the analyzed market‐derived fin samples. We suggest that capacity building investments are needed in Eastern Pacific countries to increase the efficiency of border control inspections and improve the enforcement of international trade regulations for this threatened shark species. Our study highlights the utility of combining population genetics data and large‐scale market surveys to trace wildlife products back to the starting point in the supply chain and support the assessment of emerging management and conservation measures for exploited sharks.

Three-dimensional numerical simulation of gas-liquid falling film flow characteristics on the airside of finned-tube heat exchanger with a typical large fin pitch

The closed-type heat-source tower (CTHST) heat pump system is a more promising alternative to the conventional air-source heat pump (ASHP) unit compared with the open-type heat-source tower (OTHST) heat pump system. However, the heat transfer efficiency of the CTHST is significantly lower than that of the OTHST, resulting from its indirect heat transfer way, liquid film break-up and high gas phase pressure drop. To provide a theoretical basis for the heat-mass transfer enhancement and structural optimization design of the high-performance CTHST, a three-dimensional (3D) model taking gas-liquid interfacial friction force into consideration was established in the present paper to study counter-current and co-current gas-liquid falling film flow characteristics on the airside of the finned-tube heat exchanger (FTHE) with a typical large fin pitch used in the CTHST. The predicting results of liquid film thickness based on the established model show good agreement with those of experiments in the reference, with a maximum deviation less than 5%, meaning that this model is reliable. Then the effects of contact angle, air flow direction, air Reg and liquid film Rel on liquid film characteristics were studied. The prediction correlation of average liquid film thickness was presented. The pressure drop characteristics of gas phase were analyzed in the co-current gas-liquid flow under three different liquid film Rel. Meanwhile, the change law of interfacial friction force with air Reg was revealed. The numerical results show that the critical mass flow rate of complete film flow on the finned-tube surface with contact angle of 30° is 0.06 kg/(m⋅s). The average liquid film thickness on the surface of the FTHE is obviously higher than that on the vertical plate. There is a close and positive quadratic curve relation between average interfacial friction force and air Reg. To obtain a complete film flow and small air pressure drop, the air Reg should be less than 2190.7 and 3286.0 in the counter-current and co-current gas-liquid falling film flow, respectively.

A Numerical and Experimental Study of a Novel Heat Sink Design for Natural Convection Cooling of LED Grow Lights

Light-emitting diode (LED) grow lights are increasingly used in large-scale indoor farming to provide controlled light intensity and spectrum to maximize photosynthesis at various growth stages of plants. As well as converting electricity into light, the LED chips generate heat, so the boards must be properly cooled to maintain the high efficiency and reliability of the LED chips. Currently, LED grow lights are cooled by forced convection air cooling, the fans of which are often the points of failure and also consumers of a significant amount of power. Natural convection cooling is promising as it does not require any moving parts, but one major design challenge is to improve its relatively low heat transfer rate. This paper presents a novel heat sink design for natural convection cooling of LED grow lights. The new design consists of a large rectangular fin array with openings in the base transverse to the fins to increase air flow, and hence the heat transfer. Numerical simulations and experimental testing of a prototype LED grow light with the new heat sink showed that openings achieved their intended purpose. It was found that the new heat sink can transfer the necessary heat flux within the safe operating temperature range of LED chips, which is adequate for cooling LED grow lights.

Species composition of the largest shark fin retail-market in mainland China

Species-specific monitoring through large shark fin market surveys has been a valuable data source to estimate global catches and international shark fin trade dynamics. Hong Kong and Guangzhou, mainland China, are the largest shark fin markets and consumption centers in the world. We used molecular identification protocols on randomly collected processed fin trimmings (n = 2000) and non-parametric species estimators to investigate the species composition of the Guangzhou retail market and compare the species diversity between the Guangzhou and Hong Kong shark fin retail markets. Species diversity was similar between both trade hubs with a small subset of species dominating the composition. The blue shark (Prionace glauca) was the most common species overall followed by the CITES-listed silky shark (Carcharhinus falciformis), scalloped hammerhead shark (Sphyrna lewini), smooth hammerhead shark (S. zygaena) and shortfin mako shark (Isurus oxyrinchus). Our results support previous indications of high connectivity between the shark fin markets of Hong Kong and mainland China and suggest that systematic studies of other fin trade hubs within Mainland China and stronger law-enforcement protocols and capacity building are needed.