Large Flow Volume Research Articles

Chlorophyll Content and Photosynthetic Activity of Phytoplankton in Reservoirs of the Volga River (Russia)

Using the fluorescent method in the modification of Krasnoyarsk State University, we studied the development (as chlorophyll content, ∑CHL) and photosynthetic activity of phytoplankton in seven large flat reservoirs of the Volga River cascade (Russia) in August 2015–2017. In the period of the maximal warming of water, average ∑CHL varied in limits of 19.4–33.7 μg L−1 in the Upper Volga, 8.5–27.8 μg L−1 in the Middle Volga, and 5.2–11.3 μg L−1 in the Lower Volga. The photosynthetic activity coefficient (PhAC) varied mostly in limits of 0.12–0.59, with an average of 0.22–0.38 and only in 2017 decreased to minimal < 0.10 and average < 0.20. The average PhAC values show the normal physiological state of the phytoplankton of the Upper Volga during all periods of observation, with an occasional decrease in PhAC in the Middle Volga and low photosynthetic activity in the Lower Volga. A decrease in the average ∑Chl and PhAC in 2017 was under cyclonic windy weather with a large amount of precipitation, low solar radiation, and large volume of flow. A trend towards a decrease in ∑CHL, like a decrease in PhAC from the Upper Volga to the Lower Volga, is explained by an increase in the flow rate and volume of runoff downstream of the Volga River.

Multiple debris-resisting barriers with basal clearance: A study on impact force

Optimising debris-resisting barriers is of paramount importance on constructing cost-effective and eco-friendly mitigation works. Multiple barriers with basal clearance can potentially serve as an optimal approach because they can facilitate flow energy dissipation, reduce the impact force on each barrier, ease the maintenance and resist a large flow volume. However, the design impact force of multiple barriers with basal clearance remains empirical. In this study, physical model tests were carried out to investigate the impact force of idealised dry granular flow against dual rigid barriers with basal clearance using a 5-m-long flume model. Measured impact forces show that basal clearance attenuates the impact force exerted on the second barrier by apportioning the impact forces from basal discharge and overflow. Basal discharge dissipates the kinetic energy of landing flow and reduces the impact force of overflow. A rational design of basal clearance serves as an efficient measure for optimising the design of multiple barriers.

Contained-Reflected Megaturbidites of the Marnoso-arenacea Formation (Contessa Key Bed) and Helminthoid Flysches (Northern Apennines, Italy) and Hecho Group (South-Western Pyrenees)

Contained-reflected beds deposited by fully-ponded or partially-reflected turbidity currents are important because their correct evaluation can give important indications on the degree of basin confinement and on the type, size and orientation of the morphological obstacle. Through a detailed facies analysis of various significant megabeds in the Marnoso-arenacea Formation, including the Contessa key bed, in the helminthoid flysches in the northern Apennines (Italy) and in the Pyrenees (megaturbidite MT5), this work proposes a depositional model that is well consistent with the recent experimental data available in the literature, discussing their strengths and limits. The Contessa and flysch megabeds fit very well with the experimental conditions because they are deposited in narrow and elongated confined basins characterized by axial flows. Indeed, in the proposed model, it is possible to recognize facies deposited by: 1) a basal underflow directed towards the bounding slope (Facies A), 2) an intermediate part of the flow characterized by lateral deflections (facies B1), 3) an upper well-developed reversing flow (facies B2) and 4) an uppermost residual reversing flow recording the final collapse of the fine-grained suspended load forming a poorly-sorted slurry facies C and a very thick mudstone unit D. Facies A, B1 and B2 are usually separated by very thin fine-grained muddy drapes rich in carbonaceous matter, which can be traced throughout the basin. These drapes - very common in contained and confined beds in these settings - can be related to internal density surfaces, along which decoupling processes, separating underflows from reversing overflows, can easily occur. Conversely, as the MT5 is characterized by a source transversal to an elongated narrow basin, the large flow volume versus basin capacity hinders the generation of reversing flows and rebound layers favoring the formation of fully-ponded pulsating overflows able to deposit alternations of laminated and massive units. This facies type can be observed in the basins that are characterized by axial flows only near the basin margins where the pulsating collapse of the reversing flow can dominate. This study shows that the integration of detailed field studies are essential to validate experimental data from an applicative point of view.

Computational study on the performance improvement of axial-flow pump by inlet guide vanes at part loads

In order to investigate the influence of adjustable inlet guide vanes on the hydraulic performance of axial-flow pump and impeller, the axial-flow pump with different inlet guide vane adjustable angles was simulated based on the RNG k-e turbulent model and Reynolds time-averaged equations. The multivariate non-linear regression prediction model was established about the effect of adjustable inlet guide vane on the hydraulic performance of axial-flow pump based on the numerical simulation. The performance curves of axial-flow pump with different inlet guide vane adjustable angles were obtained by calculation, showing that the performance curve shifts towards larger flow volume in case the guide vanes are turned from positive to negative angle. With the increase of inlet guide vane positive angle, the optimum operating of pump is closer to smaller operating condition, but the hydraulic efficiency of pump is lower. The larger the flow is, the larger the decreasing amplitude of pump efficiency is. With the decreases of inlet guide vane negative angle, the higher hydraulic efficiency of pump increases first then decreases. The inlet guide vane angle affects the axial velocity distribution of the blade trailing edge.

Alleviating Water Scarcity in the Central Rift Valley Lakes through an Inter-Basin Water Transfer, Ethiopia

Demand for fresh water, as one of the major natural resources, is increasing rapidly with increasing development and environmental degradation. The continued abstraction of water from Lake Ziway and its main feeder rivers Meki and Katar for irrigation indicates that the water demand may soon exceed the supply. To illustrate disparities in spatial distribution of water resources, the Upper Awash sub-basin, which shares a water-divide with the CRVL sub-basin, has large flow volumes particularly in the rainy season and suffers with seasonal flooding. The rationale behind regaining the water in CRVL relies on this non-uniform spatial distribution of fresh water, calling for a balance between water surplus and deficit regions. For this reason, Inter Basin Water Transfer (IBWT) is suggested as a viable option to augment utilizable water resources of the Upper Awash sub-basin to reduce the significant pressure on the water supply of the rapidly developing urban and irrigation areas in the CRVL sub-basin. A water evaluation and planning (WEAP) model was used to quantify the amount of surplus water in the donor basin, when examining the hydrological dynamics of the basins. Furthermore, optimal flow diversion scenarios were generated by maintaining two baseline scenario constraints. The estimated surplus water in the rainy season is expected to contribute 18 million cubic meters (mcm), 88 mcm and 192 mcm in months June, July and August respectively under average conditions. The optimal amount of diverted water could potentially stabilize the environmental degradation of Lake Ziway and Lake Abijata by compensating for development-driven abstraction and surface water evaporation respectively.

Experimental Investigation of Lateral Subsurface Flow Depending on Land Use and Soil Cultivation

The magnitude and timing of flood events are influenced by surface and subsurface flow generation as well as by present land use distribution. An integrated understanding of the interactions of soil properties, land use and flow generation is still missing. Therefore, field experiments are required to gain further knowledge about land use dependencies of discharge generation and concentration processes. In our research, we built an experimental setup consisting of three sites with similar soil and topographic conditions and different land use types (cropland, grassland, forest). The applied multimethod approach includes meteorological parameters, soil moisture, soil moisture tension, surface runoff, lateral subsurface flow, and stream discharge observations. The results show that low subsurface flow discharges more often occur at the cropland site, while large flow volumes were mainly observed at the grassland site. A correlation of the horizontal distribution of subsurface flow volumes and the accumulation areas of the surface topography has been found (r² = 0.76). The observed average response times for advective events increase from the forest site (6.0 h) to the grassland site (12.4 h) to the cropland site (20.9 h). Response times of convective events were shorter than 1 h at all sites.

Abstract WP386: Age-Dependent Ultrasonographic Changes After Indirect Revascularization Surgery in Patients With Moyamoya Disease

Objective: Pediatric patients with moyamoya disease (MMD) were supposed to have better neovascularization by indirect revascularization than adult patients with MMD, but the evidence was limited. The aim of this study was to assess age-dependent ultrasonographic changes after indirect revascularization in moyamoya patients. Methods: We prospectively enrolled moyamoya patients receiving indirect revascularization and ultrasonographic exams before and after surgery at 1, 3, and 6 months. The sonographic parameters included peak-systolic velocity (PSV), end-diastolic velocity (EDV), flow resistance, and flow volume (FV) in the superficial temporal artery (STA) and external carotid artery (ECA). The values and percentage changes of the sonographic parameter at the aforementioned time points were compared between pediatric and adult patients. Results: There were 47 hemispheres in pediatric and 16 hemispheres in adult patients with MMD receiving indirect revascularization. Before surgery, adult patients had higher EDV, lower resistance, and larger FV in the STA and ECA compared to pediatric patients (all p <0.05). After surgery, pediatric patients had higher PSV in the STA and ECA compared to adults, but the resistances of these 2 arteries remained higher in pediatric patients than that in adults (all p <0.05). The percentage changes of PSV in the STA at 3 and 6 months, FV in the STA at 3 months, as well as PSV and FV in the ECA at 6 months in pediatric patients were all larger than those in adult patients (all p <0.05). Conclusion: Pediatric patients with MMD had larger increase of PSV and FV in the STA and ECA after indirect revascularization than adult patients.

Color Doppler ultrasonography as an alternative tool for postoperative evaluation of collaterals after indirect revascularization surgery in Moyamoya disease.

The cerebral hypoperfusion caused by chronic progressive stenosis or occlusion of intracranial arteries in moyamoya disease can be treated by direct bypass or indirect revascularization procedures. The extent of collaterals from the external carotid artery (ECA) after indirect revascularization surgery is the key point of angiographic follow-up, and the invasiveness of angiography impelled us to investigate the role of ultrasonography in the evaluation of collaterals. We hypothesized that the collaterals shown on angiography might produce corresponding hemodynamic changes in color Doppler ultrasonography. We prospectively recruited moyamoya patients who underwent indirect revascularization surgery and received both preoperative and postoperative angiography and color Doppler ultrasound studies. The collaterals on angiography were graded according to Matsushima method. A total of 21 patients (age, 17 ± 10.2 years) with 24 operated hemispheres were enrolled. Patients who showed better collateral establishment by angiography had higher end-diastolic velocity (EDV), lower resistance index (RI), and larger flow volume in the superficial temporal artery (STA) and ECA (all p < 0.05). In STA, increase of EDV greater than 13.5 cm/sec or reduction of RI greater than 0.19 after operation corresponded to 94% of Matsushima grade A+B. In ECA, post-operative EDV greater than 22 cm/sec or increase of EDV greater than 6.4 cm/sec also corresponded to 94% of Matsushima grade A+B. Our findings revealed potential roles of color Doppler ultrasonography in identifying patients with poor collaterals after indirect revascularization procedures.

Dry granular flow interaction with dual-barrier systems

Multiple barriers are commonly installed along predicted geophysical flow paths to intercept large flow volumes. The main criterion for multiple-barrier design is volume retained. The velocity of the incoming (far-field) undisturbed flow is also sometimes used, although this neglects the influence of other obstacles on the flow characteristics. This study investigates the influence of upstream flow–barrier interaction on downstream runup and impact mechanisms of a dual rigid barrier system. Four physical flume tests were performed using dry sand to investigate flow interaction with dual barriers. Moreover, three-dimensional finite-element simulations were conducted to back-analyse the flume tests and to investigate the effects of upstream barrier height and barrier spacing on downstream impact characteristics. Two key interaction mechanisms that alter downstream flow are identified: (a) flow momentum redirection (i.e. runup) at the upstream barrier, reducing pre-impact momentum at the downstream; and (b) downstream flow-thinning. Runup mechanisms at the upstream barrier and flow-thinning between the two successive barriers have profound effects on dynamic impact pressures at the downstream barrier. When the upstream barrier height is taller than twice the maximum flow thickness, flow energy can be dissipated effectively by momentum redirection. The downstream barrier height and design impact pressure can be reduced up to 17% and 35% for dry sand flows, respectively.

Flood forecasting in large rivers with data-driven models

Results from the application of adaptive neuro-fuzzy inference system (ANFIS) to forecast water levels at 3 stations along the mainstream of the Lower Mekong River are reported in this paper. The study investigated the effects of including water levels from upstream stations and tributaries, and rainfall as inputs to ANFIS models developed for the 3 stations. When upstream water levels in the mainstream were used as input, improvements to forecasts were realized only when the water levels from 1 or at most 2 upstream stations were included. This is because when there are significant contributions of flow from the tributaries, the correlation between the water levels in the upstream stations and stations of interest decreases, limiting the effectiveness of including water levels from upstream stations as inputs. In addition, only improvements at short lead times were achieved. Including the water level from the tributaries did not significantly improve forecast results. This is attributed mainly to the fact that the flow contributions represented by the tributaries may not be significant enough, given that there could be large volume of flow discharging directly from the catchments which are ungauged, into the mainstream. The largest improvement for 1-day forecasts was obtained for Kratie station where lateral flow contribution was 17 %, the highest for the 3 stations considered. The inclusion of rainfall as input resulted in significant improvements to long-term forecasts. For Thakhek, where rainfall is most significant, the persistence index and coefficient of efficiency for 5-lead-day forecasts improved from 0.17 to 0.44 and 0.89 to 0.93, respectively, whereas the root mean square error decreased from 0.83 to 0.69 m.

Hydropower converters with head differences below 2·5 m

Hydropower with very low head (VLH) differences constitutes a largely unused potential source of renewable energy. A literature review of hydropower converters for VLH differences covering the engineering literature from the 1830s onwards was conducted to assess the potential of historic, current and emerging technologies. The results showed that a large number of different interesting technologies were used/developed, and that several novel and promising concepts are currently under development. Technologies emerged for different market segments: water wheels for low flow rates, turbines for large flow volumes. To take account of increased ecological demands and the desire for cost reduction, further improvements of existing technologies and new converter technologies have been developed. Other concepts described in the literature were apparently never applied although they promise development potential. The information gathered allowed for a comparison of available technologies with respect to area of application, performance, ecological impact and cost level.

Numerical simulation on the risk of roof water inrush in Wuyang Coal Mine

Water-inrush in mine is one of the mine disasters caused by mining. In order to assess the risk of roof water-inrush in Wuyang Coal Mine based on the geological material of the coal mine, we built numerical models for the roof fracture and seepage development rule by using RFPA2D and COMSOL respectively, to analyze the changes in fracture zone, stress, water pressure and seepage vector with the advancement of working face, and compared the results with the field investigated data. The numerical simulation results indicate that: (1) with the advancement of the working faces, the stress relief range and fracture zone in the overlying strata increased rapidly up to about 90m, and then tended to remain constant, reaching a final height of about 95m which agrees with the field investigation; (2) the seepage flow constantly increased with a larger flow volume both in the front and rear area, where the stress concentration are the most serious.

Brainstem congestion due to carotid-cavernous fistula via a shunt from the external carotid artery

Venous congestion of the brainstem is an extremely rare complication of carotid-cavernous fistula (CCF). Here, we report a case in which MR imaging revealed characteristic changes associated with a simultaneous increase in pressure in the ophthalmic vein and anterior pontomesencephalic vein. Our patient was a 76-year-old woman who had been diagnosed with spinocerebellar ataxia type 31, had exophthalmos, conjunctival congestion in her left eye, worsening dysarthria, and gait instability. Ten days later, she was admitted to our hospital. A neurologic examination conducted upon admission revealed mydriasis, loss of light reflex, impaired superolateral movement of the left eye, and worsening ataxia with gait difficulty and slurred speech. Laboratory examinations revealed only high levels of serum anti-cardiolipin IgG antibody and the presence of cerebrospinal fluid myelin basic protein, but no other suggestive data of an inflammatory event. T2-weighted MRI revealed a dilated left superior ophthalmic vein and hyperintensity of the pons, mainly on the left side (Fig. 1a), which was depicted as low signal area with a linear high signal lesion in diffusion-weighted images (Fig. 1c), and T1-weighted imaging revealed an isointense mass with ring-shaped contrast enhancement after injection of gadolinium (Fig. 1b). Cerebral angiography confirmed the presence of a very weak, direct, highflow CCF in the left external carotid artery (Fig. 1d, e). The MR venography and venous phase of the angiography did not show any occlusion of veins. Methionine positron emission tomography revealed no tracer uptake in the lesion, which excluded the possibility of a brain tumor. Her symptoms were rapidly getting well before we tried an endovascular treatment. At 4 months, the MRI images showed a high signal spot at the left cerebellar peduncle and slight high signal on the left side of the pons (Fig. 1a). Most cases of idiopathic and traumatic CCF have been reported to be caused by dural arteriovenous fistulas (DAVF) [1]. The providing angiography images showed a shunt from the external carotid artery to the cavernous sinus. According to the Barrow classification, we diagnosed this case as an indirect fistula [2]. The pathomechanisms of venous congestion of the brainstem in CCF remain unknown, but variations in the drainage pattern of the superior petrosal sinus (SPS) and engorged veins in the surrounding brainstem were speculated to be important factors in most of the cases. A large flow volume shunted via the CCF [3, 4], occlusion of the superior or inferior petrosal sinus [5, 6], thrombosis of the dural sinuses or veins of the posterior fossa [4], and variations in venous drainage [7] have been speculated to be primary triggers for venous congestion. The most likely pathomechanism in this patient is that the CCF initially drained via the ophthalmic vein and recruited the prepontine venous plexus for drainage following partial thrombosis of the cavernous sinus. For the cause of the partial thrombosis, we speculate the possible mediation of antiphospholipid-related antibodies because antiphospholipid antibodies are known to be associated with cerebral venous thrombi, and recent studies have suggested that venous congestion and retrograde flow may cause a dysfunctional venous circulation [8]. Y. Ito N. Sanjo (&) K. Ishikawa O. Tao T. Yokota H. Mizusawa Department of Neurology and Neurological Science, Graduate School of Medical and Dental Science, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8519, Japan e-mail: n-sanjo.nuro@tmd.ac.jp

Applying GIS to assess the vulnerability of the Päijänne water-conveyance tunnel in Finland

Using GIS, relevant hydrogeological, geological and technical data on the Paijanne Tunnel in Finland were assembled with regional environmental datasets for spatial analysis of vulnerability and environmental risk. This 120-km rock tunnel conveys potable water to the Helsinki metropolitan area. It is connected to local groundwater circulation through fractures and, consequently, it is at risk from contaminant transport. The observed heterogeneity in the occurrence of superficial deposits, in fracturing in the rock mass and in hydraulic activity are used to recommend alternatives for (1) focusing the assessment and eventual protective measures; and (2) for delineating the recommended zone of caution for protection of tunnel water. Central criteria in identifying vulnerable locations are the spatial distribution of interlinked highly localized groundwater inflows measured inside the tunnel and the iteratively interpreted fracture zones. Among the relevant considerations for assessing risk are the large volume of flow in the tunnel, the irregular distribution of potentially hazardous human activities, and the interplay of natural and human-influenced factors. The study demonstrates a visual and expressive approach using GIS to support sound land-use planning and water resource protection, based on the geology and taking into account of the dynamics of the underground construction.

Mapping agricultural fields with GPR and EMI to identify offsite movement of agrochemicals

Offsite movement of waterborne agrochemicals is increasingly targeted as a non-point source of water quality degradation. Our research has indicated that subsurface water movement is variable and site-specific, and that a small soil volume frequently conducts a large volume of flow. This concentrated flow is usually caused by soil morphology, and it often results in water moving rapidly offsite from certain areas of fields; little or no lateral subsurface flow may occur in other areas. Identifying these subsurface regions is difficult using conventional soil survey and vadose zone sampling techniques. In this study, traditional surveying is combined with electromagnetic induction (EMI) and ground-penetrating radar (GPR) mapping to identify areas with high potential for subsurface offsite movement of agrochemicals, optimizing these identification techniques, and expanding the mapping procedures to make them useful at the field-scale for agricultural production practices. Conclusions from this research are: (1) EMI mapping provides rapid identification of areas of soil with a high electrical conductivity and presumably high potential for offsite movement of subsurface water, (2) GPR mapping of areas identified by EMI mapping provides a means to identify features that are known to conduct concentrated lateral flow of water, and (3) combining the capabilities of EMI and GPR instrumentation makes possible the surveys of large areas that would otherwise be impossible or unfeasible to characterize.

The flood of the Nenjiang river and the Songhua river in 1998 and the comprehensive management of the river basins

In the summer of 1998, an exceptionally serious flood, with the characteristics of high water level, large volume of flow, long duration and serious losses caused by the disaster, occurred in the Nenjiang River basin and the Songhua River basin. Greater flood peak occurred three times in the trunk stream of the Nenjiang River for the floods occurred in its tributaries one after another. At Jiangqiao Hydrometric Station, the water level was 141.90 m and the rate of flow was 12 000 m3/s. The flood is ranged to a catastrophic one, which occurs once in 50 years. Ranged to a catastrophic flood at Qiqihar Hydrometric Station that occurs once in 400 years, its water level, 0.89 m higher than the former alltime highest, was 149.30 m and the corresponding rate of flow was 14 800 m3/s. The water level that exceeded the all-time highest lasted for 7 days. At Harbin Hydrometric Station, the water level, 0.59 m higher than the former all-time highest, was 120.89 m and the corresponding rate of flow was 17 400 m3/s. The water level that exceeded the all-time highest lasted for 9 to 10 days. The flood here is ranged to a catastrophic one, which occurs once in 150 years. The flood of the Nenjiang River damaged 456 × 104 ha of crops and 115 × 104 rooms and the direct loss of economy exceeded 40 billion yuan(RMB). The main reasons of the flood are great rainfall, long flood season, unreasonable land use, regional ecological environment degradation and lack of water control projects. It is obvious that the following measures are greatly needed: the comprehensive management of the river basins; the formulation of development planning of the river basins, especially the water control projects; the development of agriculture based on ecological security.

Methoden zur Verminderung der Ablagerungsbildung in Wärmeübertragern

AbstractMethods for Reducing Deposits in Heat Exchangers. The formation of deposits has long (too long) been considered to be unavoidable and to lie outside the responsibility of the designer. Owing to the enormous operating and investment costs caused by deposit formation and to the development of new processes which are precluded by deposit formation, a number of methods have been developed for reducing or completely preventing the fouling of heat exchangers. The lowest investments are required for chemical fluid processing, which can be retro‐fitted to an existing plant. However, for long term operation with large flow volumes or on use of toxic additives this advantage can shift towards mechanical cleaning processes. Consideration of the reduction of fouling already during the design of a heat exchanger means that it becomes feasible to build much smaller (and hence also lighter) heat exchangers.

Controlling Pulsed Incompressible Flow

Unit operations continue to be evolved for the production of fuel from waste. One such device, the active pulsed‐flow air classifier, called for the design of a valve to pulse the airflow. This valve had to be capable of pulsing airflow at frequencies ranging from 0.5–5 Hz; approximating a sawtooth waveform; inducing and varying pulse asymmetry; working in incompressible flow; handling large flow volumes; posing minimal obstruction to the airflow when fully open; closing to varying degrees; and consuming a minimum of power. This work discusses the development of testing of three configurations. Design of the valve elements most affected by special operational requirements is discussed. Techniques of analysis are presented. The louvered valve is identified as the best valve; its design equations are developed. The best control system was electropneumatic. It was geographically impossible to combine the two, although they are forecast to make up the best system.

Design Considerations for Manual Irrigation/Aspiration Device

Manual irrigation/aspiration (I/A) devices of Binkhorst, Gills, McIntyre, Simcoe and the author are described and compared regarding design, safety, efficacy and ease-of-use. Incorporating ideal characteristics, namely large flow volume, low cost, high speed, no lagtime for aspiration or reflux, steam sterilizability curved tip, aspirating hand separate from hand-piece hand, high suction capability and reliability; an optimized I/A instrument is presented.

Arteriography: The State of the Art

The papers on the subject of angiography which appear in this issue of Radiology are illustrative of the many approaches to the opacification of the arterial tree of the human body that are now available. The extent of local disease processes and anatomic variations may limit any given approach to a particular artery, with the possible exception of the direct percutaneous needle puncture of the vessel in question. In some instances direct percutaneous puncture of the left carotid artery is necessary for its opacification, regardless of the status of adjacent vessels. The generalization that optimal visualization of an artery is obtained when the contrast material is injected as close as possible to the area of interest still holds. In many situations, however, the desired information can be obtained by an intravenous injection by way of the arm veins or by utilizing the next compartment in the system, the right atrium. The right atrium is an elastic chamber which is vented in three directions and can tolerate a forceful injection of a large amount of contrast material. Right ventricular injection and introduction of the catheter tip into the pulmonary artery are also in common usage. With these approaches smaller volumes of contrast medium are employed than for right atrial injection. The veins most commonly used for percutaneous needle punctures are those of the upper extremity. Catheters may be introduced into various arm veins or into the femoral veins. Turning to arterial approaches, the arteries of the head and neck may be opacified by introduction of a needle into the brachial artery, which, with the axillary and subclavian arteries, serves as an extension catheter, or actual tubing may be percutaneously or surgically introduced into the brachial artery and advanced to an appropriate level. The axillary artery and subclavian artery have been used as puncture sites for the introduction of contrast material either by needle or by tubing. Percutaneous arterial catheters may be introduced into the femoral artery, also, and advanced to or into the mouth of any aortic branch. Direct needle puncture of the carotid, vertebral, and abdominal aortic vessels is still common practice. In the event of severe obstruction in proximal branches or in a branch through which the catheter would pass, direct needle puncture may become necessary. Contrast material can be introduced, on occasion, into the left side of the circulation by passage of a venous catheter through an intracardiac or great vessel communication, as well as by transatrial septal injection using the Ross needle. The use of an injector capable of introducing the material at a pressure of several hundred pounds per square inch is mandatory for catheter injection of any type requiring retrograde flow, such as brachial injection for opacification of vessels in the head and neck and for catheter aortography where a large volume of flow requires rapid delivery.