Transient tests for locating and sizing illegal branches in pipe systems

In pipe systems illegal branches can take away remarkable water resources with negative effects from both the economic and technical points of view. Difficulties in pointing out illegal branches by means of steady-state pressure and discharge measurements are mainly due to the fact that, of course, such systems are not active according to a regular time schedule. In this paper the possibility of using Transient Test-Based Techniques (TTBT) for the location and sizing of branches is shown. Specifically, tests carried out in different branched pipe systems at the Water Engineering Laboratory of the University of Perugia, Italy, show that TTBT allow us to detect branches irrespective of whether they are active or not. To improve the precision of the localization, arrival times of pressure waves are detected by means of wavelet analysis. Finally, a simple relation based on the water hammer theory is proposed to size the branch reliably

Leak behaviour in pressurized PVC pipes.

The correct definition of the leak law, i.e. the relationship between the leak outflow, the total head at the leak and other relevant parameters such as the pipe material, can seriously affect the accuracy of the numerical models used for the management of water distribution systems, either if they are used to forecast the leakage reduction by pressure management or to locate and size the leaks within an inverse analysis. In recent decades the use of the classical Torricelli or orifice equation has been questioned in the sense that some experimental results clearly demonstrated that the assumption of a leak outflow proportional to the square root of the head drop can yield unsatisfactory results. To investigate this behaviour, an experimental activity has been carried out at the Water Engineering Laboratory of the University of Perugia, Italy. Part of the results of the carried out tests are presented in this paper for a leak in a polyvinyl chloride (PVC) pipe. Leak laws based on the assumption of a leak area variation with the pressure are compared and validated by strain measures close to the leak

Experimental investigation of leak hydraulics

In recent decades the hydraulics of leaks, i.e. the definition of the relationships linking the hydraulic quantities in pipes with leaks, has received increasing attention. On the one hand, the definition of the relationship between the leak outflow and the relevant parameters – e.g. the leak area and shape, the pressure inside the pipe and outside the leak, and the pipe material – is crucial for pressure control and inverse analysis techniques. On the other hand, if the effect of the leakage on the governing equations is not taken into account, i.e. the loss of the flow axial momentum is not considered, significant errors can be introduced in the simulation of water distribution systems. In this paper, the governing equations for a pipe with a leak are derived. The basic equations, obtained within different approaches, are presented in a consistent formulation and then compared with the results of some experimental tests. The leak jet angle and other major features of the results are analysed. The estimated values of the parameters can be used in the water distribution network models when pipes with a diffuse leakage are considered

Equivalent hydraulic resistance to simulate pipes subject to diffuse outflows

In water distribution network simulation models, pipes subject to diffuse outflow, either due to connections or to distributed demand or to leaks along their length, are generally converted into pipe elements only subject to lumped demand at their ending nodes. This approximation, which disregards the flow variation along the pipes, generates a loss of axial momentum, which is not correctly taken into account in the present generation of water distribution network models. In this paper a correction to the lumped demand approximation is provided and this equivalence is analyzed within the framework of the Global Gradient Algorithm. This is obtained through a correction of the pipe hydraulic resistance; this approach has proven to be more effective than the use of an asymmetrical lumped demand of the total distributed outflow at the pipe ending nodes. In order to assess the effect of the introduced correction, an application to a simple water distribution system is finally provided

Detection and sizing of extended partial blockages in pipelines by means of a stochastic successive linear estimator

Effective water system management depends upon knowledge of the current state of a water pipeline system network. For example, in many cases, partial blockages in a water pipeline system are a source of inefficiencies, and result in an increase of pumping costs. These anomalies must be detected and corrected as early as possible. In this study, an algorithm is developed for detecting blockages by means of pressure transient measurements and estimating the diameter distribution resulting from their formation. The algorithm is a stochastic successive linear estimator that provides statistically the best unbiased estimate of diameter distribution due to partial blockages and quantifies the uncertainty associated with these estimates. We first present the theoretical formulation of the algorithm and then test it with a numerical case study

Non-Intubated Thoracic Surgery: Standpoints and Perspectives

Non-intubated video-assisted thoracic surgery (NI-VATS) combines the advantages of a non-intubated surgery with the benefits of a minimally invasive approach. First, NI-VATS is performed in the case of fragile patients when general anesthesia and/or orotracheal intubation can be foreseen as inconvenient. However, NI-VATS indications have been increasingly extended to different patient conditions, considering the increasingly assessed safety and feasibility of the procedure. Currently, the NI-VATS approach is used worldwide for different thoracic surgery procedures, including the management of malignant pleural effusion, surgical treatment of empyema, anatomical and non-anatomical lung resection, and other indications. In fact, this approach has shown to be less impactful than VATS under general anesthesia, allowing for shortened hospitalization and faster recovery after surgery. Besides, NI-VATS is associated with fewer pulmonary complications, less respiratory distress, and a mild systemic inflammatory reaction. For these reasons, this approach should be considered not only in patients with poor cardiac or respiratory function (general functional reserve), but also in other eligible conditions. We explored the anesthetic and surgical aspects of such an approach, including the management of analgesia, cough reflex, depth of sedation, and intraoperative technical issues to put this approach in perspective

Anomaly pre-localization in distribution–transmission mains by pump trip: preliminary field tests in the Milan pipe system

In this paper, the reliability of transients due to pump trip as a powerful tool for the pre-localization of anomalies in real pipe systems is tested. The examined pipe system is part of the one supplying the city of Milan, Italy and is managed by Metropolitana Milanese SpA (MM). The characteristics of such a system can be considered as intermediate between those of classical transmission mains and distribution systems because of its several branches. A Lagrangian model simulating pressure wave propagation is used to evaluate the pipe pressure wave speed – associated with a genetic algorithm – and to locate possible anomalies – associated with wavelet analysis. The results of the diagnosis of the pipe system are corroborated by repairs executed by MM in the area where possible anomalies have been pre-localized

Post Mortem Ultrasound and Computed Tomography Findings of an Extraluminal Urinary Bladder Leiomyoma in a Dog

Background: Neoplasia of the urinary bladder is common in dogs, accounting approximately 0.5 to 1.0 percent of all neoplasms. Most of the neoplasia of the urinary bladder is epithelial in origin and only 10% of urinary bladder neoplasms in dogs are from mesenchymal origin, of which the most frequent types are leiomyoma / leiomyosarcoma, and hemangioma / hemangiosarcoma. Virtual autopsy refers to the postmortem use of radiology, ultrasound and cross-sectional imaging prior to conventional necropsy. This paper reports the detection of a rare extra-luminal urinary bladder mass diagnosed as leiomyoma with a virtual autopsy techniques.Case: A 16-year-old male Schnauzer had previous history of seizure and no complains related to the urinary system. The animal was treated symptomatically to the neurological signs and responded to medical treatment. Nine weeks later from the first visit to the hospital the dog was found dead at home. Then postmortem ultrasound and computed tomography of the abdomen were performed. Postmortem ultrasound revealed a homogenously hypoechoic, rounded and slightly irregularly marginated mass located externally but adjacent to the left cranial wall of the urinary bladder and appears to extend from its serosal margins. Postmortem computed tomography was performed after postmortem ultrasound. A pedunculated homogenous soft tissue attenuating mass was located at the left lateral aspect of the urinary bladder and extended cranially. It had a stalk that connected to the left lateral wall of the urinary bladder. A partial necropsy of the abdomen was done just to examine the mass. A round extraluminal, pedunculated mass was observed at the left lateral aspect of the urinary bladder wall. It was pale pink on the outside and white inside, with a soft to firm consistency. The lumen and mucosal surface of the urinary bladder was smooth and regular. The histology of the mass revealed a densely cellular neoplastic proliferation, expansive, composed of spindle-shaped cells with moderate to large eosinophilic cytoplasm, sometimes wavy and with indistinct edges. The nuclei were large, oval to flattened, with dense chromatin and inconspicuous nucleoli. Anisocytosis and anisokariosis were discrete and no mitotic figures were observed. The arrangement consisted of dense, irregular and multidirectional bundles and the stroma was scarce. The mass was histologically confirmed as leiomyoma.Discussion: In this case, we performed postmortem ultrasound and computed tomography as part of a virtual necropsy study and in both modalities the urinary bladder mass was able to be identified, followed by a partial necropsy to further investigate the nature of the mass and to collect a sample to obtain the histological diagnosis. A few of the disadvantages of the postmortem ultrasound and computed tomography specially in this case were the lack of color Doppler investigation on ultrasound and the lack of evaluation of the patter of contrast enhancement on computed tomography. These techniques could have added important information related to the vascularity characteristics of the mass in a live patient. This is the first case report in veterinary medicine that describes an extra-luminal pedunculated urinary bladder leiomyoma in a canine patient, and it is emphasized the approach by postmortem ultrasound, postmortem computed tomography and conventional necropsy findings to reach the definitive diagnosis