Operational Charts Research Articles

Optimization of Dualistic Reservoir System Two-Dimensional Rule Curve with Three Allocation Rules

A two-dimensional operation chart is commonly used to manage the operation of a dual-reservoir system, where the water storage in each reservoir is accurately considered in the water-supply decision. The dual reservoir chart should be combined with one allocation rule to better represent water supply distribution between reservoirs. In this study, the 2D rule curve was coupled with three allocation rules: variable allocation ratios, fixed allocation ratios, and compensation regulation, to identify the efficiency of using these rules with the 2D rule curve in operating the dual reservoirs. Mosul-Dukan dual reservoirs in Iraq were implemented as a study area using monthly data extended from 2001 to 2020. The Shuffled Complex Evolution Algorithm was used to optimize the water allocation ratios. The results revealed that the variable allocation ratios were superior to the other two rules in terms of water deficit, in which the total water shortage of the variable allocation ratios rule was 56590 Mm3. The total shortage was less than that obtained by the fixed allocation ratio and compensation regulation rules by 0.9% and 56%, respectively. Finally, the variable allocation ratio was more suitable for application with a 2D reservoir rule curve than the two remaining rules (fixed allocation ratio and compensation regulation rules). The variable allocation ratios sustainably manage reservoirs in the regions that suffer from water scarcity and represent the most vulnerable to the impact of climate change. Doi: 10.28991/CEJ-2024-010-02-04 Full Text: PDF

Fully Endoscopic Nontubular Retractor Approach for Intraaxial Tumors.

Fully endoscopic or endoscope-controlled approaches are essentially keyhole approaches in which rigid endoscopes are the sole visualization tools used during the whole procedure. At the early attempts of endoscope-assisted cranial surgery, it was noted that rigid endoscopes enabled overcoming the problem of suboptimal visualization when small exposures are used. The technical specifications and design of the currently available rigid endoscopes are associated with a group of unique features that define the endoscopic view and lay the basis for its superiority over the microscopic view during brain surgery. Fully endoscopic resection of intraparenchymal brain tumors is a minimally invasive approach that is not routinely practiced by neurosurgeons, with a few major series published so far. Unfamiliarity with the technique, steep learning curve, and concerns about inadequate exposure and decreased visibility may explain this fact. The majority of the purely endoscopic resections for intraparenchymal brain lesions are performed nowadays through tubular retractor systems. In very limited instances, however, the fully endoscopic technique is performed without tubular retractors. In this chapter, we elaborate on the surgical technique and nuances of the fully endoscopic nontubular retractor approach for intraaxial tumors. From a prospective database of endoscopic procedures maintained by the senior author, clinical data, imaging studies, and operative charts and videos of cases undergoing fully endoscopic excision for intraaxial brain tumors were retrieved and analyzed. The pertinent literature was also reviewed. The surgical technique of the fully endoscopic nontubular retractor approach for intraaxial tumors was formulated. The endoscopic technique has many advantages over the conventional procedures. In our hands, the technique has proven to be feasible, efficient, and minimally invasive with excellent results.

Fully Endoscopic Resection of Frontal Osteomas.

Osteomas are the most common primary bone tumors of the calvaria, with an incidence of less than 0.5%. In skull vault osteomas, the exostotic form that grows from the outer table is more common than the enostotic ones which arise from the inner table and grow intracranially. Osteomas of the forehead are very noticeable and disfiguring; patients usually seek medical advice for cosmetic reasons. Forehead osteomas were traditionally excised via either a direct incision over the lesion using the naturally occurring creases or a conventional bicoronal flap. More recently, endoscopic approaches for excision of forehead osteomas were introduced. The results were very encouraging and the technique was adopted by many groups worldwide yet with many technical variations. In this chapter we elaborate on the surgical technique and nuances of the fully endoscopic resection of frontal osteomas. From a prospective database of endoscopic procedures maintained by the senior author, clinical data, imaging studies, operative charts, and videos of cases of forehead osteomas were retrieved and analyzed. The pertinent literature was also reviewed. The surgical technique of the fully endoscopic resection of frontal osteomas was formulated. The endoscopic technique has many advantages over the conventional procedures. In our hands, the technique has proven to be less time-consuming, efficient, and minimally invasive with excellent cosmetic results.

Fully Endoscopic Supraorbital Approach for Anterior Cranial Base Meningiomas.

Anterior cranial base meningiomas include those meningiomas originating from the tuberculum sellae, the planum sphenoidale, or the olfactory groove, with surgical excision being the main treatment modality for these tumors. Conventional microscopic and endoscope-assisted versions of the supraorbital keyhole approach via an eyebrow incision emerged into minimally invasive options that are frequently utilized nowadays for treating these tumors. At the early attempts of endoscope-assisted cranial surgery, it was noted that rigid endoscopes enabled overcoming the problem of suboptimal visualization when small exposures are used. The technical specifications and design of the currently available rigid endoscopes are associated with a group of unique features that define the endoscopic view and lay the basis for its superiority over the microscopic view during brain surgery. Notwithstanding, the fully endoscopic or endoscope-controlled version of the supraorbital keyhole approach is not routinely practiced by neurosurgeons, with few series published so far. In this chapter we elaborate on the surgical technique and nuances of the fully endoscopic supraorbital approach for anterior cranial base meningiomas. From a prospective database of endoscopic procedures maintained by the senior author, clinical data, imaging studies, operative charts, and videos of cases undergoing fully endoscopic excision of anterior cranial base meningiomas via supraorbital approach were retrieved and analyzed. The pertinent literature was also reviewed. The surgical technique of the fully endoscopic supraorbital approach for anterior cranial base meningiomas was formulated. The fully endoscopic supraorbital approach for anterior cranial base meningiomas has many advantages over the conventional procedures. In our hands, the technique has proven to be feasible, efficient, and minimally invasive with excellent results.

Fully Endoscopic Retrosigmoid Approach for Cerebellopontine Angle Tumors.

Fully endoscopic or endoscope-controlled approaches are essentially keyhole approaches in which rigid endoscopes are the sole visualization tools used during the whole procedure. At the early attempts of endoscope-assisted cranial surgery, it was noted that rigid endoscopes enabled overcoming the problem of suboptimal visualization when small exposures are used. The technical specifications and design of the currently available rigid endoscopes are associated with a group of unique features that define the endoscopic view and lay the basis for its superiority over the microscopic view during brain surgery. Fully endoscopic retrosigmoid approach for cerebellopontine angle tumors is a minimally invasive approach that is not routinely practiced by neurosurgeons, with few series published so far. Unfamiliarity with the technique, steep learning curve, and concerns about inadequate exposure, neurovascular injury, and decreased visibility may explain this fact. In this chapter we elaborate on the surgical technique and nuances of the fully endoscopic retrosigmoid approach and present an overview of the published series. From a prospective database of endoscopic procedures maintained by the senior author, clinical data, imaging studies, operative charts, and videos of cases undergoing fully endoscopic retrosigmoid approach for cerebellopontine angle tumors were retrieved and analyzed. The pertinent literature was also reviewed. The surgical technique of the fully endoscopic retrosigmoid approach was formulated. The endoscopic technique has many advantages over the conventional procedures. In our hands, the technique has proven to be feasible, efficient, and minimally invasive with excellent results.

Long-term operation rules of a hydro–wind–photovoltaic hybrid system considering forecast information

The large-scale integration of wind and solar energy into cascade hydropower stations increases the complexity of hydraulic/electrical relationships and requires a modification of conventional scheduling mode for better energy system performance. This study focuses on the long-term operation rules for hydro–wind–photovoltaics (PV) hybrid energy systems (HESs). Based on the conventional operation chart, a cascade energy operation chart that couples wind, PV output, and runoff forecasts is proposed to obtain the total output of HES, which can promote the utilization of the joint regulation of cascade hydropower stations. A total output allocation method based on the cascade energy operation chart is established to coordinate the operation of each power station. Then an operation chart optimization model with objectives of maximizing power generation and output reliability is proposed to improve HES performance. The case study reveals that compared with the conventional reservoir operation chart, 1) the optimized cascade energy operation chart increased power generation of HES by 9.2 %; 2) the reservoir impounding timing was delayed, the drawdown timing was brought forward, and the drawdown depth was increased; 3) the reliability of HES power output was improved, and the output corresponding to the 95 % guaranteed rate requirement was increased by 18 %.

Assessment of geomembrane strain from pond liner bubbles

Bubbles (a.k.a. whales) that develop from gas entrapped beneath a geomembrane in pond liner applications lead to localized increases in geomembrane strain that warrant evaluation. Results from three-dimensional, geometrically-nonlinear, finite-element analysis are presented to show how geomembrane stiffness, fluid depth, volume of entrapped gas, and interface friction affect the deformed shape of, and maximum strain in the geomembrane. It is shown that the deformed geomembrane follows a bell-shaped curve and that geomembrane strain increases as the fluid depth increases until the bubble is submerged. The extent to which the maximum strain increases with decreasing geomembrane stiffness and increasing volume of entrapped gas are quantified. Design and operation charts are presented to provide a practical means of assessing strain in existing geomembrane bubbles or identify maximum fluid depths to limit geomembrane strain to a target value.

Experimental study on the influence of electrical conductivity of hygroscopic compounds on the performance of a hygroscopic cycle

Dry climate conditions and the risk of desertification have increased significantly due to the effects of climate change. This fact, combined with the growing energy demand, leads to the need of research focused on improving the performance and efficiency of power plants. In the Hygroscopic Cycle Technology, recently implemented at industrial scale, steam condensation is performed in an absorber using solutions of hygroscopic compounds in water. Hygroscopic effects increase the condensing temperature for a given pressure, allowing the implementation of dry coolers at high ambient temperatures and eliminating cooling water consumption. In this work, due to their relevance in the cycle performance and control, the influence of the concentration of hygroscopic salts in the cycle has been studied, providing insight into proper operational ranges and key parameters. An experimental study of the influence of make-up water quality, with the concentration of impurities measured by water electrical conductivity and cycle mass flow ratio values has been performed in a pilot plant. The results, used to validate a mass and species conservation model, have allowed to obtain operational charts of the cycle and may help to reduce the amount of instrumentation required for cycle control. It was found that the decrease in electrical conductivities with boiler blowdowns in the cycle stabilized at a boiler blowdown ratio of 5%. Blowdown ratios above 10% did not result in substantially lower boiler Cycles Of Concentration in comparison with the increase of thermal energy losses and pumping power (0.42 kJ/kg for each additional 1% of blowdown). It was also found that the ratio between the cooling reflux and turbine steam conductivity had to be higher than 1.1 for condensation by absorption to occur, and that a minimum blowdown ratio of 0.04% was required to avoid using a droplet separator to control live steam quality. Hence, a compromise in the boiler blowdown ratio must be found for each particular application. Finally, hygroscopic effects in condensing pressure and temperature have been experimentally verified at pilot plant scale, leading to potentially higher cycle power output values and higher temperatures in the cooling stream of industrial power cycles, which may make it easier to reject heat from the cycle.

Autologous Tooth Transplantation in Craniofacial Malformations.

To evaluate the applicability of transplanted teeth in young patients with craniofacial anomalies. Observational study. Comprehensive Centre for Cleft Palate and Craniofacial Malformations. Patients with craniofacial anomalies who underwent tooth transplantation. Only children with complete clinical and radiological documentation and a follow-up period of at least 1.5 years were included. Tooth transplantation. Retrospective evaluation of clinical records, pre- and postoperative radiographs, and operative charts. Clinical characteristics of patients, preoperative parameters and postoperative outcome parameters were collected. A total of 17 patients with 23 tooth transplantations were included. The median follow-up period was 6.7 years. The pooled survival and success rates were 91%. Notably, one out of two teeth that were transplanted into the bone grafted alveolar cleft site had to be extracted, which might indicating a higher risk for this procedure. In total, two transplanted teeth had to be extracted during the follow-up period, one due to external resorption and the other one due to perio-endo lesion. One patient needed endodontic treatment due to pulp necrosis. We consider tooth transplantation to be a reliable and suitable procedure in the dental rehabilitation of young patients with craniofacial anomalies and fitting concomitant circumstances. We encourage craniofacial teams to reconsider this option more frequently in appropriate cases.

A Model of Froth Flotation with Drainage: Simulations and Comparison with Experiments

The operation of a froth flotation column can be described by a nonlinear convection–diffusion partial differential equation that incorporates the solids–flux and drift–flux theories as well as a model of foam drainage. The resulting model predicts the bubble and (gangue) particle volume fractions as functions of height and time. The steady-state (time-independent) version of the model defines so-called operating charts that map conditions on the gas and pulp feed rates that allow for operation with a stationary froth layer. Operating charts for a suitably adapted version of the model are compared with experimental results obtained with a laboratory flotation column. Experiments were conducted with a two-phase liquid–bubble flow. The results indicate good agreement between the predicted and measured conditions for steady states. Numerical simulations for transient operation, in part for the addition of solid particles, are presented.

Kinodynamic Generation of Wafer Scanners Trajectories Used in Semiconductor Manufacturing

The operation time of an ideal reliable wafer scanner model is defined at the die level where the actual exposure process takes place as the time unit per die, or at the wafer substrate level as the time unit per wafer substrate. Therefore, the machine throughput is given as the reciprocal of the operation time. The involved motion profiles of a machine, namely the step-and-scan trajectories, function as the heartbeats that drive its multidisciplinary elements, which suggests that a multidisciplinary design optimization should be involved when such profiles are selected or designed. This is also true when considering the traverse motion profiles among rows and columns within the wafer substrate. The step-and-scan trajectories affect the machine throughput, performance, and die yield. The effects of tracking such profiles appear as structural vibration, tracking errors, and thermal loading at various machine elements such as the actuators, the reticle, the wafer, and the projection elements specifically when the exposure high-energy duration and frequency are not taken into consideration while designing the reference motion. From the dynamics perspective, having a reference motion with nonzero and bounded higher-order derivatives is recommended since it enhances the tracking performance of the machine, however, its ability to increase the operation time is usually overlooked. In an attempt to understand such effects, we present a case study that outlines the aforementioned aspects using three step-and-scan profiles of mainly <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$3^{rd}$ </tex-math></inline-formula> -order. Taking the dynamics of the driven stage into consideration through input shaping, both the step-and-scan and traverse motion profiles are analyzed. We provide analytical expressions that can be used to generate both types of motion profiles on the fly without additional optimization. A simulation example of a simplified wafer scanner machine shows the usefulness of the proposed framework. Note to Practitioners—Choosing the most suitable operating conditions of a lithography machine is challenging. These conditions affect machine productivity, profit margin, and maintenance. In this paper, we reveal the relation between the selection of operating conditions based on several decision variables- and the kinodynamic step-and-scan trajectory generation based on specific machine parameters and clients’ requirements. Being chart-based, the selection process of an operating point can be less practical at some points. However, using appropriate curve fitting tools, the information provided in the optimal operating charts can be put into suboptimal closed-form expressions that facilitate the selection process. Therefore, the designed trajectories parameters can be easily saved in lookup tables for ease of evaluation and future use. This helps in accommodating changes in the operation plans and flexible manufacturing systems. Also, starting with a given set of machine parameters, it is possible to calculate the optimal machine operating point when the input shaping technique is used, as illustrated in this paper.

A degenerating convection–diffusion system modelling froth flotation with drainage

Abstract Froth flotation is a common unit operation used in mineral processing. It serves to separate valuable mineral particles from worthless gangue particles in finely ground ores. The valuable mineral particles are hydrophobic and attach to bubbles of air injected into the pulp. This creates bubble-particle aggregates that rise to the top of the flotation column where they accumulate to a froth or foam layer that is removed through a launder for further processing. At the same time, the hydrophilic gangue particles settle and are removed continuously. The drainage of liquid due to capillarity is essential for the formation of a stable froth layer. This effect is included into a previously formulated hyperbolic system of partial differential equations that models the volume fractions of floating aggregates and settling hydrophilic solids [R. Bürger, S. Diehl and M.C. Martí, IMA. J. Appl. Math. 84 (2019) 930–973]. The construction of desired steady-state solutions with a froth layer is detailed and feasibility conditions on the feed volume fractions and the volumetric flows of feed, underflow and wash water are visualized in so-called operating charts. A monotone numerical scheme is derived and employed to simulate the dynamic behaviour of a flotation column. It is also proven that, under a suitable Courant-Friedrichs-Lewy condition, the approximate volume fractions are bounded between zero and one when the initial data are.

Actual Problems of Operation of Turbine and Pumping Equipment of Pumped Storage Power Plants

The article discusses matters concerned with the performance efficiency of pumped storage power plants (PSPP) and its governing factors. The specific features pertinent to the operation of PSPP turbine and pumping equipment are analyzed along with the approaches used at Russian power facilities to diagnose their state in line with the applicable regulatory and technical framework. Pressing matters concerned with diagnosing the state of PSPP equipment are identified with taking into account the experience gained from their operation and designing in Russia and around the world. The identified matters generate the need to carry out studies aimed at finalizing the approaches to diagnosing the technical state of turbine and pumping equipment, and perfecting the relevant regulatory and technical framework. Features and malfunctions pertinent to the operation of pumping and turbine equipment along with the related features and malfunctions of generator (motor) equipment that are encountered at PSPPs in Russia and around the world are pointed out; the most frequent of which are identified, and their causes are analyzed. In our opinion, these features should be selected taking into account in calculating the technical condition index of the PSPP turbine and pumping equipment. To achieve more efficient operation of the PSPP turbine and pumping equipment, the composition of the plant’s operating generating and pumping equipment should be selected with taking into account the effect the operation chart of the connected equipment and its technical state have on the total generation/consumption of electricity; in addition, measures for diagnostics and maintenance of PSPP equipment should be taken in a more regulated manner.

Drug-Related Problems in Pulmonary Hypertension with Valvular Heart Disease.

The occurrence of drug-related problems (DRPs) and their causes specifically among pulmonary hypertension (PH) with valvular heart disease (VHD) has not been evaluated and is unknown. Therefore, this study aimed to determine the percentage of occurrence, types, and causes of DRPs among PH with VHD patients. An observational retrospective study was conducted at Cardiology Centre, Hospital Serdang, from 1st January to 30th April 2021. Data were collected from medication charts, medical progress notes, laboratory and operative charts through electronic Health Information System (eHIS). The types and causes of DRPs were identified and classified based on Pharmaceutical Care Network of Europe's (PCNE) classification system V9.02. The data were analyzed using descriptive statistics. All patients (100%) experienced at least one DRP. Total number of DRPs identified was 120 encounters which were associated with 503 causes. The majority of problems were related to treatment effectiveness (59.1%) and treatment safety (33.4%). The causes of DRPs are mainly related to inappropriate monitoring including therapeutic drug monitoring (18.6%), inappropriate combination of drugs, or drugs and dietary/herbal supplement (10.3%), drug dose was too high (8.9%), drug dose was too low (8.2%) and inappropriate timing of administration or dosing intervals (7.7%). The percentage of DRP occurrence was high in the studied population. Treatment effectiveness and treatment safety issues were the main DRPs identified with various preventable causes. The findings may be useful to guide the planning of measures to prevent and solve future DRPs in the population.

A generalized reservoir module for SWAT applications in watersheds regulated by reservoirs

Accurate estimates of reservoir outflow are important for simulating runoff of watersheds regulated by large reservoirs using hydrological models. The target release reservoir module widely used in the Soil and Water Assessment Tool (SWAT) shows poor performance in simulating the outflow and water level of large multipurpose reservoirs. In this study, a generalized reservoir operation chart-based reservoir module is developed as an alternative to the original reservoir module in SWAT (SWAT-Or). The proposed reservoir module includes a dynamic decision-based outflow framework integrated into the operation chart. The modified version of SWAT with the new reservoir module (SWAT-M) is not only suite for small reservoir with flood control function but also more applicable to large multipurpose reservoir. The predictions obtained from the original and new reservoir modules are compared with measured data from the three largest reservoirs in the Dongjiang River basin, South China. The performance of SWAT-M and SWAT-OR for daily and monthly runoff simulations of four hydrological stations in the basin are compared. The results shows that the proposed module produces results closer to the field measurements and has fewer errors than the original module, which predicts inappropriate low reservoir outflow during dry periods. In addition, the runoff simulation by SWAT-M shows a significant improvement, in particular for stations directly influenced by large reservoirs. The monthly (daily) scale R2 of SWAT-M is 0.02 to 0.21 (0.14 to 0.44) higher, and the NSE is 0.11 to 0.30 (0.12 to 7.16) higher than that of SWAT-Or. The proposed reservoir operation chart-based module significantly improves the applicability of SWAT to simulate runoff in watersheds regulated by large reservoirs.

Optimal Energy Storage Operation Chart and Output Distribution of Cascade Reservoirs Based on Operating Rules Derivation

An energy storage operation chart (ESOC) is one of the most popular methods for conventional cascade reservoir operation. However, the problem of distributing the total output obtained from the ESOC has not yet been reasonably solved. The discriminant coefficient method is a traditional method for guiding the output distribution by determining the order of reservoir supply or storage; however, it cannot quantify the water used in operation. Thus, this study develops a new output distribution model using a polynomial fitting method and an artificial neural network to express the functional relationship derived from the deterministic optimization results of long-term runoff series to maximize power generation. Cascade reservoirs of the lower reaches of the Jinsha River in China were selected for the case study. Compared to the discriminant coefficient method, the proposed method can rationally distribute the total output, thus avoiding the problem of concentrated deserting water in downstream reservoirs that occurs in the discriminant coefficient method. In general, this study proposes an effective alternative method to guide cascade reservoir operation.

Optimisation of passive solar systems seasonal operation in conditions of central Europe

The paper deals with optimisation of passive solar systems installed on family and office buildings in central Europe locations. In these territories, in contrast to more southern countries, it is not typical to utilize passive solar systems on public or private buildings. Although these systems can significantly influence thermal comfort inside the buildings, many controversions and myths reduce wider utilisation. It could be expected, that new European legislative tending to common energy savings will cause also wider usage of these systems. In contrast of classic countries utilizing passive solar systems, the benefits can be expected either in hot season or in cold season. If we focus on systems that can supplement existing buildings – roller blinds and slats, significant energy and economy benefits can be easily reached. These systems can either decrease or avoid overheating during hot summer days or to limit thermal loses in cold winter days and nights. This paper compares various roller blind and slat systems installed on office building and family house. Exact measurements explains the influence on thermal gains, thermal loses and thermal comfort in particular storeys during constituent seasons. The main results of these experiments and calculations are principles of operational charts for particular locations in the buildings leading to provable energy savings and economy profits. The measurements also serve as verification of computer simulations.

Neglected Monteggia Fractures in Children—A Retrospective Study

(1) Background: A Monteggia fracture is an infrequent injury in children. It can be missed during an initial consultation in 20–50% of patients. Chronic radial head dislocation may lead to several complications. Thus, surgical reconstruction of chronic Monteggia injuries is justified. The aim of this study is to analyze the single tertiary center experience in the treatment of neglected Monteggia fractures. (2) Methods: A retrospective study of patients treated for missed Monteggia fractures was conducted. Hospital records, operative charts, follow-up records and a set of X-rays were analyzed for each patient. Radiographic results were graded as good, moderate or poor. The functional status of elbows was estimated using the Mayo Elbow Performance Index. (3) Results: A total of 13 patients (8 boys and 5 girls) aged 4–12 years (mean 7.15) were treated during the study period. An angulation osteotomy of the ulna was performed in ten patients and a radial shortening osteotomy in three patients. A Bell–Tawse annular ligament reconstruction was performed in five patients, and a direct repair was performed in two patients. Eight patients had radiocapitellar trans-fixation. There were nine good radiographic results, three moderate and one poor. The functional result was excellent in nine patients, good in three and poor in one. (4) Conclusions: Our work has many limitations (only 13 patients and different types of operations), and conclusions should be drawn very carefully from such a small and diverse group. The surgical reconstruction of neglected Monteggia fractures in children should be attempted in all patients. Angulation and elongation osteotomies of the ulna are suitable for most patients. If there is a marked overgrowth of the radius, gradual ulnar lengthening and radial head reduction using the Ilizarov method may be a better option. Annular ligament reconstruction is not mandatory.

Operation and Interaction of Software Used in Digital Distribution Channels in Direct Marketing of Hotels

With the development of technology, the ways of doing business are changing, and digital transformations are taking place in the activities of businesses. At this point, digital transformation is reflected in the service businesses in two ways. The first of these is the digital transformation in the operational activities of business management, while the second is in the form of technological innovations offered to guests. To this end, this research focuses on the digital transformation in the operational activities of hotel businesses and aims to determine the operation and interaction of the software offered in digital distribution channels for direct marketing of hotels. In this direction, 57 software companies that provide the relevant software services to hotels in Turkey were accessed, and content analyzes were made on the websites of the relevant companies. In light of the data obtained, the operation chart for the interaction of the software that plays an active role in the direct marketing of the hotels was created and explained by presenting sample quotes from the websites of these businesses. It is expected that the research can contribute to the literature for digital marketing courses in the tourism and hotel management departments of universities, as well as reveal the operation of the interaction of the software in question.

Retrolabyrinthine transsigmoid approach to complex parabrainstem tumors in the posterior fossa.

The surgical management of large and complex tumors of the posterior fossa poses a formidable challenge in neurosurgery. The standard retrosigmoid craniotomy approach has been performed at most neurosurgical centers; however, the retrosigmoid approach may not provide enough working space without significant retraction of the cerebellum. The transsigmoid approach provides wider and shallower surgical fields; however, there have been few clinical and no cadaveric studies on its usefulness. In the present study, the authors describe the transsigmoid approach in clinical cases and cadaveric specimens. For the clinical study, the authors retrospectively reviewed the medical records and operative charts of patients who had been surgically treated for parabrainstem tumors using the transsigmoid approach between 1997 and 2019. They analyzed patient demographic and clinical data, as well as surgical and clinical outcomes. In the cadaveric study, they compared the surgical views obtained in different approaches (retrosigmoid, presigmoid, retrolabyrinthine, and transsigmoid) and measured the sigmoid sinus width at the level of the endolymphatic sac and the distance between the anterior edge of the sigmoid sinus and the endolymphatic sac on 35 sides in 19 cadaveric specimens. A total of 21 patients (6 males and 15 females) with a mean age of 42.2 (range 15-67) years were included in the clinical study. Eleven patients had meningioma, 7 had vestibular schwannoma, 2 had hemangioblastoma, and 1 had epidermoid cyst. Gross-total, near-total, and subtotal removal were achieved in 7 (33.3%), 3 (14.3%), and 11 (52.4%) patients, respectively. In the cadaveric study, 19 cadaveric specimens were used. The sigmoid sinus was cut in the middle, and the incision was extended from the retrosigmoid to the presigmoid dura. The dura was then retracted upward and downward like opening a door. The results indicated that this technique can widen the operative field anteriorly by approximately 2 cm as compared to the retrosigmoid approach and provides a better view anterior to the brainstem. The transsigmoid approach is useful for complex parabrainstem tumors in the posterior fossa because it provides a wider and shallower operative view with less retraction of the cerebellum. This enables safer tumor removal with less damage to important structures in the posterior fossa, resulting in better operative and clinical outcomes.