Real-time Zone Research Articles

Microwave Ablation of Renal Cell Carcinoma.

Management options for small renal masses include active surveillance, partial nephrectomy, radical nephrectomy, and thermal ablation. For tumors typically ≤3 cm in size, thermal ablation is a good option for those desiring an alternative to surgery or active surveillance, especially in patients who are considered high surgical risk. We favor microwave ablation because of the more rapid heating, higher temperatures that overcome the heat sink effect of vessels, reproducible cell kill, and a highly visible ablation zone formed by water vapor that corresponds well to the zone of necrosis. For central tumors, we favor cryoablation because of the slower formation of the ablation zone and less likelihood of damage to the collecting system. With microwaves, it is important to monitor the ablation zone in real time (ultrasound is the best modality for this purpose), avoid direct punctures of the collecting system, and to place probes tangential to the collecting system to avoid burning open a persistent tract between the urothelium and extrarenal spaces or causing strictures. The surgical steps described in this video cover our use of high-frequency jet ventilation with general anesthesia to minimize organ motion, initial imaging and targeting, probe insertion, hydrodissection (a technique that enables displacement of adjacent structures), the ablation itself, and finally our dressing. Postoperative cares typically consist of observation with a same-day discharge or an overnight stay. Follow-up includes a magnetic resonance imaging abdomen with and without contrast, chest X-ray, and laboratories (basic metabolic panel, complete blood count, and C-reactive protein) 6 months postablation. Overall, percutaneous microwave ablation is an effective and safe treatment option for renal cell carcinoma in both T1a and T1b tumors in selected patients with multiple studies showing excellent oncologic outcomes when compared with partial and radical nephrectomy.

Fast calculation of 3D radiofrequency ablation zone based on a closed-form solution of heat conduction equation fitted by ex vivo measurements

Fast calculation or simulation of the ablation zone induced by radiofrequency ablation (RFA) has a critical role in hepatic RFA planning and therapy. However, it remains challenging to approximate the ablation zone in real time, especially when more than one probe is involved in one ablation session. This paper presents a novel computational technique to calculate the 3D ablation zone of one probe RFA and two-probe switching RFA. The main idea is to get an approximate solution of the temperature distribution from a simplified Pennes bioheat equation, and further fit the solution to the coagulation measurements on ex vivo porcine liver. With a closed-form solution of temperature distribution, the calculation of the ablation zone is as simple as the commonly used ellipsoidal model, but it allows a more realistic prediction of combined ablation zones with different inter-probe spacing. The new approximation technique could potentially replace the original ellipsoidal model in the intervention planning step.

New computational framework for modeling the gravity flow behavior of sublevel caving material

Abstract A better understanding of the gravity flow mechanism of caved material is required to increase ore recovery in caving mining. This study presents a novel computational framework PRF3D (3D particle random flow) capable of simulating the flow behavior of caved ore and rock in sublevel caving mining. The PRF3D framework combines the advantages of the discrete element method and stochastic medium theory and uses the billboard technique of OpenGL to render and visualize particles. The new framework can automatically record the ore recovery indicators, display the shape of the draw zone in real time and capture the fines percolation. An isolated physical draw experiment is conducted to validate the accuracy and efficiency of the PRF3D from both qualitative and quantitative perspectives. After validation, various numerical tests are conducted to investigate the influence of the sublevel height, drawpoint spacing, drawpoint size and particle size of overlaying rock on the multidraw behavior of caved ore and rock in sublevel caving mining. The performance of PRF3D is also demonstrated by benchmarking with the reported simulations.

Control and Optimization of Melting Zone Parameters by Means of a Two-Dimensional Model in the Blast Furnace Automated Process Control System

A two-dimensional mathematical model of BF is developed that describes gas dynamic, heat and mass transfer processes over the height and cross section of a furnace from the charging level to the iron taphole. A two-dimensional mathematical model is implemented as part of five existing MMK blast-furnace production automatic control systems for the melting zone in real time. The systems used are already installed in the furnaces as means of automation, microprocessor and computer engineering. Continuous automatic control and quantitative evaluation of the parameters of the melting zone (MZ) shape, location, and thickness are provided. This makes it possible to compare these MZ parameters with smelting input and output parameters, reveal their effect on the melting parameters and to estimate them quantitatively, and to conduct continuous automatic monitoring of changes in MZ parameters in time. It is shown that a change in the shape of the MZ (increasing the angle at the periphery and axis of the furnace), its ascent over the height of the furnace (from the line of the combustion zone), and an increase in its thickness worsen furnace performance. Values of the MZ parameters are established that provide the best smelting indices. Continuous automatic monitoring of changes in MZ parameters over time and comparison of results with trends in the change of smelting parameters make it possible to identify the causes of disruption in BF operation and take timely measures to overcome them.

Percutaneous Image-Guided Cryoablation in Vascular Anomalies.

Understanding and management of vascular anomalies has always been intriguing. These disorders exhibit an expected pattern of clinical presentation and progression, and characteristic imaging findings. Significant progress in understanding and treating patients with vascular anomalies has been made in the past quarter century. Newer multidisciplinary domains for treating these disorders with medical drugs and less invasive image-guided or surgical procedures are constantly evolving. Vascular anomalies can exhibit aggressive tumor-like behavior resulting in recurrence or persistent symptoms after treatment. Thermal ablation has been widely used in tumor treatment. This has generated interest on using thermal ablation for treating vascular anomalies. Percutaneous image-guided cryoablation is increasingly used for this purpose as compared with other ablation technologies. Availability of small caliber cryoprobes and the ability to monitor the freeze zone in real time have made this an attractive option to interventional radiologists. These experiences are relatively new and limited. It is helpful to understand the emerging role of this technology in the treatment of vascular anomalies.

US-US Overlay Fusion Imaging in the Evaluation of Treatment Response After RFA

Recent advancements in technology permit two-dimensional (2D) multiplanar reconstruction images of CT or MRI to display in the same plane as US images in real time. It was reported that fusion imaging–guided RFA was useful in the treatment of hepatic malignancies that were inconspicuous on B-mode US. Moreover, the application of fusion imaging allows display of the tumor before and during/after ablation on the same US images side by side, and the imaging overlays can show the tumor image before ablation within an ablated hyperechoic zone in real time. Therefore, the image overlay of US–US fusion imaging can visualize the ablative margin three dimensionally according to the US probe action. We have developed US–US overlay fusion imaging in RFA for hepatocellular carcinoma. US–US fusion imaging has 3 clinical applications in RFA therapy. The first is the real-time monitoring of RFA lesion formation. Clinicians can employ B-mode US to observe the bubble-related hyperechoic region and preliminarily evaluate the ablation zones comparing the pre-ablation image of the tumor using US–US fusion imaging. The second application is related to decision making about additional ablation. We could confirm any lesion with a poor ablative margin during the session, and then extend the necrotic area by additional ablation. The third is visualization of the safety margin on US. Although the endpoint of conventional RFA cannot be based on objective evidence with US, US–US fusion imaging offers an evidence-based quality improvement in RFA therapy. In conclusion, US–US fusion imaging could show tumor images before ablation and the ablative area on US in real time. The image overlay of US–US fusion could visualize the ablative margin of RFA on US. Therefore, US–US fusion imaging can contribute to RFA therapy with a safety margin, that is, the so-called precise RFA.

Yield Response to Variable Rate Irrigation in Corn

To investigate the impact of variable rate irrigation on corn yield, twenty plots of corn were laid out under a center pivot variable rate irrigation (VRI) system in an experimental field near Stoneville, Mississippi. The VRI system is equipped with five VRI zone control units, a global positioning system (GPS) receiver, and computer software. Each zone control unit controls the duty cycle of the sprinklers in the zone to realize variable rate water application across the pivot lateral. The GPS receiver determines the pivot position for identification of the control zone in real time. Supplemental irrigation was scheduled based on evapotranspiration (ET) estimates. A randomized complete block design was used in this study, with five irrigation rate treatments (0, 50%, 75%, 100%, and 125% of the rate determined using the Arkansas Irrigation Scheduler) and four replications. During the growing seasons in 2012 and 2013, VRI prescriptions were created based on the experimental design, and wirelessly uploaded to the system to apply varying amounts of water to each plot. The corn was machine harvested for yield. Results indicated that effect of irrigation rate on yield was not significant in 2012 and was significant in 2013. The treatment of 125% irrigation rate had the highest yield for both years. No significant yield difference between treatments in the 2012 season could be due to the sufficient rainfall in that summer. The ET estimates used in the irrigation scheduling might be lower than actual water demand of the corn crops for a higher yield.

실시간 데이터를 이용한 지역기반 위험분석 시스템에 관한 연구

에너지 산업시설물은 다양한 종류의 가스나 유해물질을 다루고 있어 화재, 폭발, 독성물질 노출로 인한 대규모 중대사고로 전이되어 산업시설 종사자뿐만 아니라 외부 민간인에게도 치명적인 피해를 입힐 수 있다. 이러한 사고를 방지하기 위해 정량적 위험성평가를 활용하여 인체나 건물에 미칠 수 있는 영향에 대한 정량화를 시도하고 있지만 예외적인 상황에 즉각적인 처리가 어렵고 시나리오를 위한 전문가적 지식이 많이 필요하였다. 본 논문은 에너지 대규모 산업시설에서 실제 환경의 데이터를 실시간으로 이용함으로써 동적인 시나리오를 생성하여 예외적인 상황과 전문가적 지식을 최소화하고 개인 인지적 환경에 적합하게 위험을 표현하는 것이 목적이다. 이를 위해 본 연구는 실시간 정보를 기반으로 현 시점의 지역 내 위험도를 실시간으로 연산할 수 있는 데이터베이스와 증분적 모델을 적용한 지역기반 위험 분석 시스템을 설계하고 구현하였다. Energy industry facilities can cause fatal damage for internal industry employee as well as external general people because handling various kinds of gas and harmful substance might be spread to large scale severe accident by fire, explosion, and toxic gas leakage. In order to prevent these accidents, quantification by damage effect on structure and human is tried by using quantitative risk assessment, but it is difficult to process instantly exceptional cases and requires knowledge of expert. This paper aims to minimize exceptional cases and knowledge of expert, and present risk with human perceptible. So, we designed and developed zone-base risk analysis system that can compute risk of zone in real time at that point using database and incremental model.

Measuring and monitoring occupancy with an RFID based system for demand-driven HVAC operations

Abstract Building energy management and the necessity to reduce overall energy consumption is becoming an increasingly important topic. Especially in dynamic environments, where the setting and occupancy keep changing, knowing occupancy information, including the number and identities of the occupants and where they are located, can be beneficial in energy management as well as other application areas including safety, security and emergency response. In particular, occupancy information has a direct impact on various aspects of heating, ventilation, and air conditioning (HVAC) systems, such as heat loads, system running time, required heating, cooling and distribution of conditioned air, and preferred temperature set points. Energy-saving strategies can be carried out in response to real-time occupancy changes. In this paper, an RFID based occupancy detection system is proposed to support demand-driven HVAC operations by detecting and tracking multiple stationary and mobile occupants in multiple spaces simultaneously. The proposed system estimates the thermal zone where each occupant is located, and reports the number of occupants for each thermal zone in real time. The field tests yielded an average zone level detection accuracy of 88% for stationary occupants and 62% for mobile occupants. For scattering analysis, averages distances to corresponding centroids were 1.45 m and 3.24 m for stationary and mobile occupants, respectively. In order to explore the benefits of demand-driven HVAC operations, current HVAC work procedures are examined, major energy consumers in HVAC systems are identified and quantified, and energy-saving strategies are presented. This study aims to support reducing the consumption of the HVAC systems by integration of the occupancy detection system and the demand-driven HVAC operation strategies.

Acoustic emission method for research and control of friction pairs : Tribology International, Vol. 24, No. 1, pp. 11–16 (Feb. 1991)

Abstract One of the new physical methods that provides much information about the processes going on in a friction contact zone in real time is acoustic emission (AE). Basic experimental results of AE in friction are presented and analysed. Using AE signals we can get an indication about the state of the friction processes, about the quality of solid and liquid layers on the contacting surfaces in real time, sometimes about intensity of wear, changing of wear and friction regimes and so on. The influence of sliding velocity, load, roughness and some physical and mechanical properties of the body on the parameters of AE are also given. Some attention to the practical implementation of these techniques for control of capability for work of friction pairs in real conditions are given. Modern methods and devices enable condition monitoring of sliding and rolling bearings.

Acoustic emission method for research and control of friction pairs

One of the new physical methods that provides much information about the processes going on in a friction contact zone in real time is acoustic emission (AE). Basic experimental results of AE in friction are presented and analysed. Using AE signals we can get an indication about the state of the friction processes, about the quality of solid and liquid layers on the contacting surfaces in real time, sometimes about intensity of wear, changing of wear and friction regimes and so on. The influence of sliding velocity, load, roughness and some physical and mechanical properties of the body on the parameters of AE are also given. Some attention to the practical implementation of these techniques for control of capability for work of friction pairs in real conditions are given. Modern methods and devices enable condition monitoring of sliding and rolling bearings.