Robotlar ve Akıllı Sistemler Anabilim Dalı

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https://hdl.handle.net/20.500.12846/998

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Kinematics, kinetics, and forces of the knee joint during walking
(Elsevier, 2024) Karabulut, Derya; Arslan, Yunus Ziya
Motion analysis is a valuable tool to monitor the kinematics and kinetics of body parts quantitatively and the decision-making process in clinical implementations. In gait analysis systems, temporospatial parameters, joint angles, joint moments, and ground reaction forces can be recorded. However, some other biomechanical parameters such as muscle forces, joint reaction forces, and muscle-tendon unit length change cannot be noninvasively recorded in gait analysis systems. Accordingly, musculoskeletal modeling and simulation tools are very widely used to obtain such biomechanical parameters. In this chapter, we presented the details about kinematics and kinetics of the knee joint during a healthy gait. In this context, joint angles, joint moments, muscle forces, and joint reaction forces were provided. Furthermore, some special cases seen in various musculoskeletal disorders that affect the ability of gait are also investigated.
Patellar tendon advancement for the treatment of crouch gait in patients with cerebral palsy
(2023) Karabulut, Derya; Arslan, Yunus Ziya; Salami, Firooz; Wolf, Sebastian Immanuel; Goetze, Marco
Crouch gait is a frequent gait pathology in children with cerebral palsy (CP). Patellar tendon advancement (PTA) is a typical surgery among single-event multilevel surgery (SEMLS) for the treatment of crouch gait and performed to enhance the knee joint kinematics and kinetics Patella position had a considerable effect on the torque-producing capacity of the quadriceps and hence, patellar height is a typical metric to assess the influence of PTA on knee function. Patellar height can be assessed by using several radiographic imaging methods. How ever, in the literature, there is no consensus on objective quantification of the patellar height In our study, we aimed to i) objectively quantify the patella position using X-ray data and musculoskeletal modeling and ii) monitor the effect of PTA in combination with SEMLS on the knee kinematics of patients with CP and crouch gait.
Evaluation of mandibular condyle position in Class III patients after bimaxillary orthognathic surgery: A cone-beam computed tomography study
(2024) Küçükçakır, Osman; Ersan, Nilüfer; Arslan, Yunus Ziya; Cansız, Erol
This retrospective study evaluated the mandibular condyle position before and after bimaxillary orthognathic surgery performed with the mandibular condyle positioned manually in patients with mandibular prognathism using cone-beam computed tomography. Methods: Overall, 88 mandibular condyles from 44 adult patients (20 female and 24 male) diagnosed with mandibular prognathism due to skeletal Class III malocclusion who underwent bilateral sagittal split ramus osteotomy (BSSRO) and Le Fort I performed using the manual condyle positioning method were included. Conebeam computed tomography images obtained 1–2 weeks before (T0) and approximately 6 months after (T1) surgery were analyzed in three planes using 3D Slicer software. Statistical significance was set at P < 0.05 level. Results: Significant inward rotation of the left mandibular condyle and significant outward rotation of the right mandibular condyle were observed in the axial and coronal planes (P < 0.05). The positions of the right and left condyles in the sagittal plane and the distance between the most medial points of the condyles in the coronal plane did not differ significantly (P > 0.05). Conclusions: While the change in the sagittal plane can be maintained as before surgery with manual positioning during the BSSRO procedure, significant inward and outward rotation was observed in the axial and coronal planes, respectively, even in the absence of concomitant temporomandibular joint disorder before or after the operation. Further long-term studies are needed to correlate these findings with possible clinical consequences.
Estimating ground reaction forces from gait kinematics in cerebral palsy : A convolutional neural network approach
(Springer, 2024) Arslan, Yunus Ziya; Özateş, Mustafa Erkam; Salami, Firooz; Wolf, Sebastian Immanuel
Purpose While gait analysis is essential for assessing neuromotor disorders like cerebral palsy (CP), capturing accurate ground reaction force (GRF) measurements during natural walking presents challenges, particularly due to variations in gait patterns. Previous studies have explored GRF prediction using machine learning, but specifc focus on patients with CP is lacking. This research aims to address this gap by predicting GRF using joint angles derived from marker data during gait in patients with CP, thereby suggesting a protocol for gait analysis without the need for force plates. Methods The study employed an extensive dataset comprising both typically developed (TD) subjects (n=132) and patients with CP (n=622), captured using motion capture systems and force plates. Kinematic data included lower limb angles in three planes of motion, while GRF data encompassed three axes. A one-dimensional convolutional neural network model was designed to extract features from kinematic time series, followed by densely connected layers for GRF prediction. Evaluation metrics included normalized root mean squared error (nRMSE) and Pearson correlation coefcient (PCC). Results GRFs of patients with CP were predicted with nRMSE values consistently below 20.13% and PCC scores surpassing 0.84. In the TD group, all GRFs were predicted with higher accuracy, showing nRMSE values lower than 12.65% and PCC scores exceeding 0.94. Conclusion The predictions considerably captured the patterns observed in the experimentally obtained GRFs. Despite limitations, including the absence of upper extremity kinematics data and the need for continuous model evolution, the study demonstrates the potential of machine learning in predicting GRFs in patients with CP, albeit with current prediction errors constraining immediate clinical applicability.
İskelet kaslarındaki kuvvet üretim mekanizmasının Huxley tipi kas modelleriyle incelenmesi
(2021) Arslan, Yunus Ziya
Hareketin gerçekleştirilmesinde birincil rol oynayan ve lokomotor sistem bileşenlerinden olan iskelet kasları, kasılma esnasında çeşitli biyokimyasal ve mekanik süreçler sonucunda kuvvet üretirler. Kas kuvvetlerinin çeşitli deneysel veya klinik amaçlar için bilgisayar ortamında benzetiminin (simülasyonunun) yapılabilmesi amacıyla matematiksel kas modelleri kullanılmaktadır. Kas modellerinin, gerçek kas kuvvetlerini yüksek doğrulukla üretebilmeleri modellemede esas alınan varsayımlarla yakından ilişkilidir. Yapısal modeller olarak da bilinen Huxley tipi kas modelleri, kasılma esnasındaki biyokimyasal ve mekanik etkileşimleri esas alarak kuvvetin yanı sıra çeşitli kas karakteristiklerinin de hesaplanmasında kullanılan matematiksel modellerdir. Çapraz köprü teorisine dayanan ve kas yapısındaki filamentlerin etkileşimi üzerine kurulu bu modeller, halen deneysel çalışmaların da etkisiyle, modifiye edilmeye ve geliştirilmeye devam edilmektedir. Kas modellerinin yapısını, kullanılan varsayımları ve bu modellerin kabiliyetlerini anlamak, gerçeğe yakın kas kuvvetlerinin ve kasın dinamik karakteristiklerinin yeniden üretimi açısından önem arz etmektedir. Bu derleme makalede, Huxley tipi matematiksel kas modellerinin yapı ve özellikleri ile ürettikleri kuvvet cevapları, deneysel olarak elde edilen kas karakteristiklerini kestirmedeki performansları açısından incelenmiştir. Bu amaç doğrultusunda, çalışmada bir Huxley modeli kullanılarak farklı kasılma durumları için kas kuvvetleri elde edilmiş ve model performansları değerlendirilmiştir. Ayrıca Huxley tipi modellerde gerçekleştirilen değişimler sunulmuş, modellerin avantaj ve dezavantajlarının yanı sıra hangi tür çalışmalar için elverişli oldukları da ortaya konmuştur.
Kritik madenlerin kullanıldığı ürünler ülke ekonomisine katkı sunar
(2024) Özkan, Şafak Gökhan
Geleceğin katma değerli ekonomisinde belirleyici unsurlar arasında sadece lityum, grafit, kobalt ve nikel değil bor, nadir toprak elementleri, bakır, altın, gümüş, manganez, titanyum, demir, silisyum ve alüminyum içeren mineraller de giderek daha kritik bir rol oynamaktadır. Bu tip madenler, enerji dönüşümü, sürdürülebilirlik, yüksek teknoloji üretimi ve stratejik ekonomik avantajlar açısından büyük öneme sahip olmakla birlikte lityum, kobalt, nikel ve grafit, elektrikli araçlar (EV'ler) ve yenilenebilir enerji depolama sistemlerinin bataryalarında kullanılmaktadır. Elektrikli araç bataryaları ve enerji depolama çözümleri, enerji verimliliğini artırarak ve karbon emisyonlarını azaltarak önemli ekonomik değer sağlamaktadır. Nadir toprak elementleri, bor, bakır ve silisyum içeren mineraller ise rüzgâr türbinleri ve güneş panelleri gibi yenilenebilir enerji teknolojilerinde kullanılmakta ve bu teknolojiler, zaman içinde fosil yakıtların yerini alarak sürdürülebilir ekonomik büyümeye katkıda bulunmaktadır.
Evaluation of treatment protocols in surgically assisted rapid maxillary expansion by finite element analysis
(2024) Arslan, Yunus Ziya; Cihaner , Duygu; Karabulut, Derya; Dogan Onur, Ozen; Cansiz, Erol
Background and Objectives: Transverse maxillary deficiency is an important maxillary anomaly that is very common in society and remains current in orthodontics. The maxillary expansion has been used in treatment for a long time. While maxillary expansion can be performed with rapid maxillary expansion in young adults, it is performed with surgically assisted rapid maxillary expansion (SARME) in individuals who have reached skeletal maturity. No consensus has been reached on the most successful surgical technique or the ideal appliance for treating transverse maxillary deficiency. Accordingly, we aimed to evaluate various surgical techniques and orthodontic appliances for treating transverse maxillary deficiency using the finite element method (FEM) to identify the treatment protocol that minimizes stress on the maxillary bone and teeth. Materials and Methods: On the virtual models obtained from the cone beam computed tomography of a patient, two different incisions (the pterygomaxillary junction is separated and not separated) were made and combined using three different orthodontic appliances (tooth, bone, and hybrid assisted). Then, stresses over the maxillary bone and maxillary teeth were calculated by FEM. Results: Our results showed that when the pterygomaxillary plates were separated, fewer stresses were observed on the bone and teeth. Although hybrid-supported appliances created less stress on the teeth than tooth-supported appliances and no difference was found between bone-supported appliances, it was found that hybrid-supported appliances created less stress on the bone than the other appliances. Conclusions: The separation of the pterygomaxillary junction in the SARME operation and the use of a bone-supported or hybrid-supported appliance would place less stress on the bone and teeth.
The effect of papaverine on tendon healing and adhesion in rats following Achilles tendon repair
(2024) Arslan, Yunus Ziya; Can, Erdem; Dincel, Yaşar Mahsut; Karabulut, Derya; Karabağ, Sevil
The Achilles tendon, recognized as the strongest tendon in the human body, plays a pivotal role in transferring the forces generated by the gastrocnemius and soleus muscles to the calcaneus. This complex mechanism is essential for fundamental activities such as walking, jumping, and running.[1,2] Notably, the incidence of acute tendon injuries tends to rise within the age range of 30 to 40 years, predominantly affecting male individuals. These injuries are frequently linked to recreational sports, such as ball games and racket sports, that involve rapid acceleration and jumping.
Serebral palsili çocukların yürüme karakteristiğinin biyomekanik değerlendirmesi
(2020) Arslan, Yunus Ziya
Serebral palsi (SP), kas iskelet sisteminde pek çok deformiteye neden olan ve çeşitli yürüme patolojileri ile kendini gösteren bir hastalıktır. Bükük diz yürüyüşü en çok karşılaşılan yürüme problemlerinden biridir. SP’li hastaların kinetik ve kinematik parametrelerinin sağlıklı kişilere göre farklılık gösterdiği bilinmektedir. Bu çalışmada, bükük diz yürüyüşüne sahip çocukların eklem kinematiği ve kinetiği ile alt ekstremite kas kuvvetleri açısından sağlıklı bireylere göre olan farklılıklarının belirlenmesi amaçlanmıştır. Bunun için OpenSim yazılımı kullanarak SP’li hastaların ve sağlıklı bireylerin yürüme hareketinin analizi yapılmıştır. Ters kinematik analiz ile kalça, diz ve ayak bileği fleksiyon / ekstansiyon açıları elde edilmiştir. Eklem momentlerinin hesaplanması için ters dinamik yöntemi kullanılmıştır. Statik optimizasyon yöntemi ile medial hamstring, biseps femoris, rektus femoris, gastroknemius ve tibialis anterior kasları için kas kuvvetleri hesaplanmıştır. SP’li hastalardan kaydedilen elektromiyografi (EMG) verisi ile de kestirilen kas aktivasyonlarının zamanlamalarının deneysel veriyle örtüşüp örtüşmediği kontrol edilmiştir. SP’li çocuklarda kalça eklemi fleksiyon / ekstansiyon açısında sağlıklı bireylere göre farklılık gözlenmemektedir. Ancak SP’li çocuklarda diz ve ayak bileği fleksiyon/ektansiyon açılarının sağlıklı bireylerden anlamlı şekilde farklı olduğu belirlenmiştir. Kalça, diz ve ayak bileğindeki fleksiyon/ekstansiyon momentleri incelendiğinde maksimum kalça ekstansör momenti ve ikinci diz ekstansör momenti dışındaki diğer bütün parametreler için SP’li hastalar ve sağlıklı bireyler arasında anlamlı farklılıklar tespit edilmiştir. SP’li çocuklarda biseps femoris ve semimembranosus kas kuvvetleri sağlıklı kişilere göre daha yüksek bulunurken, gastroknemius, rektus femoris ve tibialis anterior kas kuvvetleri daha düşük bulunmuştur. Kestirilen kas kuvvetleri EMG verisi ile karşılaştırıldığında kasların aktivasyon zamanlarının deneysel olarak elde edilen aktivasyon zamanları ile uyumlu olduğu görülmüştür.
Direct validation of model-predicted muscle forces in the cat hindlimb during locomotion
(Journal of Biomechanical engineering-transactions of the asme, 2020) Arslan, Yunus Ziya; Karabulut, Derya; Doğru, Suzan Cansel; Herzog, Walter; Pandy, Marcus G.; Lin, Yi-Chung
Various methods are available for simulating the movement patterns of musculoskeletal systems and determining individual muscle forces, but the results obtained from these methods have not been rigorously validated against experiment. The aim of this study was to compare model predictions of muscle force derived for a cat hindlimb during locomotion against direct measurements of muscle force obtained in vivo. The cat hindlimb was represented as a 5-segment, 13-degrees-of-freedom (DOF), articulated linkage actuated by 25 Hill-type muscle-tendon units (MTUs). Individual muscle forces were determined by combining gait data with two widely used computational methods—static optimization and computed muscle control (CMC)—available in opensim, an open-source musculoskeletal modeling and simulation environment. The forces developed by the soleus, medial gastrocnemius (MG), and tibialis anterior muscles during free locomotion were measured using buckle transducers attached to the tendons. Muscle electromyographic activity and MTU length changes were also measured and compared against the corresponding data predicted by the model. Model-predicted muscle forces, activation levels, and MTU length changes were consistent with the corresponding quantities obtained from experiment. The calculated values of muscle force obtained from static optimization agreed more closely with experiment than those derived from CMC.
Biomechanical comparison of implantation approaches for the treatment of mandibular total edentulism
(Proceedings of the institution of mechanical engineers part h-journal of engineering in medicine, 2020) Arslan, Yunus Ziya; Karabulut, Derya; Kahya, Songül; Cansız, Erol
Applying four anterior implants placed vertically or tilted in the mandible is considered to provide clinically reasonable results in the treatment of mandibular posterior edentulism. It is also reported that a combination of four anterior and two short posterior implants can be an alternative approach for the rehabilitation of severe atrophy cases. In this study, we aimed to evaluate the biomechanical responses of three different implant placement configurations, which represent the clinical options for the treatment of mandibular edentulism. Three-dimensional models of the mandible, prosthetic bar, dental implant, abutment, and screw were created. Finite element models of the three implant configurations (Protocol 1: Four anterior implants, Protocol 2: Four anterior and two short posterior implants, Protocol 3: Two anterior and two tilted posterior implants: All-on-4™ concept) were generated for 10 patients and analyzed under different loading conditions including chewing, biting, and impact forces. Protocol 2 led to the lowest stress concentrations over the mandible among the three protocols (p < 0.016). Protocol 2 resulted in significantly lower stresses than Protocol 3 and Protocol 1 over prosthetic bars under chewing forces (p < 0.016). None of the implant placement protocols consistently exhibited the lowest stress distribution over abutments. The lowest stresses over dental implants under the chewing, biting, and impact forces were obtained in Protocol 1, Protocol 2, and Protocol 3, respectively (p < 0.016). Protocol 3 was the best option to obtain the lowest stress values over the screws under all types of loading conditions (p < 0.016). In conclusion, Protocol 2 was biomechanically more ideal than Protocol 1 and Protocol 3 to manage the posterior edentulism.
The effect of PEEK-Rod fixation systems on finite element lumbar spine model
(Avrupa Bilim Ve Teknoloji Dergisi, 2022) Arslan, Yunus Ziya; Akıncı, Saliha Zeyneb; Yaman, Onur; Sürmen, Hasan Kemal; Karabulut, Derya
Orthopedic fixation devices have been employed in the treatment of spinal diseases. Special fixation devices have been developed to decrease the effect of spinal injuries and deformities and have been used to decrease the neurologic back pain of the patients. In this study, the finite element spine model of an adolescent idiopathic scoliotic patient was constructed. The titanium spinal implant system and the system of polyetheretherketone (PEEK) were compared regarding their stress distributions. The finite element lumbar spine model from L2 to L5 vertebra was obtained from computed tomography scan data. The three-dimensional spine model consisted of four lumbar vertebrae, three intervertebral discs, six facet joints, and the corresponding ligaments. Loading and boundary conditions were applied to the L2-L5 lumbar model. According to the subjected loads and bending moments on the model, stress distributions were evaluated especially on the intervertebral discs, and the screw-rod implant systems both for the titanium and the PEEK-based fixation systems. The disc structures were also analyzed for the effects of adjacent segment disease, which has been reported as a post-operative effect of fusion surgeries. Ansys software was used for the simulation processes of the models without the implant system and the models with different fixation systems. Comparative investigation between different fixation systems showed that the stress distribution values were decreased with the PEEK-based fixation system. Moreover, lower total deformation and equivalent stress values were recorded with the PEEK-based fixation system, especially on L3-L4 and L4-L5 intervertebral discs. Furthermore, both spinal implant systems allowed to decrease the overall loading stress on the whole spine models. And it was concluded that the PEEK-based spinal implant system was considerably reduced the load on the discs and ligaments, and also appeared as a better option in stress reduction and load sharing when compared to the titanium spinal implant system.
Fundamentals of 3D printing and its applications in biomedical engineering
(Springer Natur, 2020) Arslan, Yunus Ziya; Sürmen, Hasan Kemal; Örteş, Faruk
Three-dimensional (3D) printing is a practical manufacturing method that allows us to transform objects designed in the digital environment into physical objects using layered manufacturing methods. The terms of rapid prototyping and additive manufacturing are also used to express the manufacturing process using 3D printers. Unlike the subtractive manufacturing (machining) approach in which 3D objects are constructed by successively cutting material away from a solid block of material, additive manufacturing processes produce parts by adding material one layer at a time. In 3D printing technology, parts with complex geometries can be manufactured using less material compared to conventional manufacturing techniques. There is no need for molding in 3D printing, and the production of a part with different geometry can be quickly adapted. Objects designed in a digital environment can be directed to the production process immediately. Three-dimensional printing, which is very suitable for the production of objects with free-form surfaces, has been widely used in the medical sector, especially in the production of patient-specific biomedical devices [1]. Three-dimensional printing applications are spreading rapidly in many areas of the medical sector. Nowadays, orthopedic implants, prostheses, orthoses, dental products, anatomical models, customized tablets for personalized medicine, and many surgical instruments can be produced using 3D printers [2–5]. Three-dimensional printing allows significant flexibility for the fabrication of biomedical devices, offering geometric freedom without limitations experienced in traditional manufacturing methods. By using the 3D printing method, we are able to print complex shaped functional parts with detailed internal features and adjust the material density to produce lighter biomedical devices with fewer parts. Since the biomedical devices and implants must be compatible with the patient’s anatomy, the production of such devices by traditional manufacturing methods is a challenging task. In addition, because these devices are supposed to be designed for patient-specific purposes, the design of each item should be independently carried out for each patient [6]. Three-dimensional printing technology does not require additional production stages such as production line installation and mold design, thereby having the advantage of manufacturing the parts immediately, which makes the 3Dprintingmethod very suitable for the production of biomedical devices. Three dimensional printing has been one of the widely preferred approaches in the biomedical sector because of its high geometrical accuracy and resolution. In addition, the ability to print complex body implants by taking into account the magnetic resonance image (MRI) [7] and computed tomography (CT) [8] data further increased the functionality of this technology. Three-dimensional bioprinting is another application area of the 3D printing technology in which the complex 3D living tissues and artificial organs are constructed [9]. It is possible to produce 3D functional and living tissues using 3D bioprinting [10]. These printers generally use materials such as hydrogel, silicon, and protein solutions. The major aim in this field is to produce functional and transplantable human organs in the near future [11]. Some disadvantages of the 3D printing method are (i) it is not economically feasible for mass production, (ii) size of the part to be manufactured is limited to the dimensions of the 3Dprinter, and (iii) production speed is relatively low. Furthermore, the variety of materials used in 3D printing is also limited. On the other hand, new strategies are being developed that allow different types of materials to be used in the 3D printing technology [12–15]. Thanks to these novel technologies, many types of metal [16], plastic [17], composite [18], and organic materials [19] can be used in 3D printing. In biomedical applications, post-processing is of particular importance. For example, stair-stepped surface, which is a result of layer-by-layer manufacturing, may lead to undesirable surface conditions for implants required biocompatibility [20]. In such cases, surface finish operations should be done carefully and precisely. Moreover, clean and sterile manufacturing environments are required in the manufacture of medical products such as implants. In this context, precautions against contamination should be carefully taken for printing platform and other 3D printer equipment [21]. In this chapter, the general working principle of 3D printers, commonly used 3D printing technologies, and types of materials used in 3D printers were addressed. In addition, scientific studies focusing on 3D printing technology in the biomedical field have been discussed.
Design of patient-specific maxillofacial implants and guides
(Springer, 2021) Arslan, Yunus Ziya; Üzel, Mehmet; Doğru, Suzan Cansel; Yağız, Abdullah; Cansız, Erol; Kocaelli, Hümeyra
With the development of three-dimensional (3D) design and manufacturing technologies, it is possible to easily manufacture various computer-aided patient-specific instruments. In the maxillofacial region, treatment of facial defects, asymmetries, and dental disorders can be done efficiently by using custom-made implants. In addition, reconstruction of the jaws even including temporomandibular joints can be performed by today’s 3D technologies. One of the most popular subjects is the use of computer-aided design and manufacturing techniques in orthognathic surgery. Postoperative outcomes of maxillofacial surgeries can be improved by integrating the patient-specific implants (PSIs) into the treatment protocol. With this novel approach, the contouring that is required to ensure the geometrical compatibility between the patient's anatomical form and the implant is eliminated. Screw positions can be planned during the preoperative simulation so as not to damage any anatomical structure. These preoperative preparations shorten the operating room time. Also, customized osteotomy and drill guides can be used to fixate the implants in the planned position, which minimizes damage possibility over the maxillofacial region and makes surgeries more accurate. The fabrication stages of such implants include (1) obtaining a three-dimensional solid body model of anatomical structures from the patient’s two-dimensional scanning images, (2) simulation of the operation on the anatomical computer model, (3) design of the PSI according to the patient’s model, (4) manufacturing of implants by using proper additive production methods. In this chapter, we described state-of-the-art studies about the development of patient-specific maxillofacial implants and guides, highlighted current insights, and focused on reported clinical outcomes. Besides, we presented the design stages of a PSI and guide for a bimaxillary orthognathic surgery.
Artificial intelligence versus natural intelligence in mineral processing
(Physicochemical Problems of Mineral Processing, 2023) Özkan, Şafak Gökhan
This article aims to introduce the terms NI-Natural Intelligence, AI-Artificial Intelligence, MLMachine Learning, DL-Deep Learning, ES-Expert Systems and etc. used by modern digital world to mining and mineral processing and to show the main differences between them. As well known, each scientific and technological step in mineral industry creates huge amount of raw data and there is a serious necessity to firstly classify them. Afterwards experts should find alternative solutions in order to get optimal results by using those parameters and relations between them using special simulation software platforms. Development of these simulation models for such complex operations is not only time consuming and lacks real time applicability but also requires integration of multiple software platforms, intensive process knowledge and extensive model validation. An example case study is also demonstrated and the results are discussed within the article covering the main inferences, comments and decision during NI use for the experimental parameters used in a flotation related postgraduate study and compares with possible AI use.
Effect of chloride salt Ions onto coal flotation based on contact angle and bubble-particle attachment time
(2022) Özkan, Şafak Gökhan; Güngören, Can; Baktarhan, Yasin; Özdemir, Orhan; Şahpaz, Orhan; Kurşun, İlgin
This study was aimed to reveal the effect of K+, Na+, Ca2+, and Mg2+ ions on the bubble-particle interactions of high-rank coal with contact angle and bubble-particle attachment time studies. The results for the contact angle experiments indicated that the contact angle of the coal, which was 62° in the absence of ions, increased slightly in the presence of mono- and divalent ions and reached a maximum (67°) in the presence of 1?10-1 mol/dm3 Mg2+, and the effect of K+ ions on the contact angle was minimal. Furthermore, the results for the bubble-particle attachment time experiments showed that the bubble-particle attachment time of coal, which was measured as 4.5 ms in the absence of ions, decreased as a function of ion concentration from 1?10-2 mol/dm3 to 1 mol/dm3. While the bubble-particle attachment times of coal particles in the presence of K+/Na+ and Ca2+/Mg2+ at low concentrations were around 2-3 ms and 1-2 ms, respectively, the increase in the concentration slightly changed the attachment time which decreased to less than 1 ms except for K+ ions. Overall, it can be concluded from this study that the effect of these dissolved ions in water was more prominent on the bubble-particle attachment time of the coal particles rather than the contact angle which showed no significant change. Also, the specific ion effect was determined as “Mg2+ > Ca2+ > Na+ > K+” in terms of the bubble-particle interactions in the presence of these ions.
Ultrasound supported flocculation of borate tailings with differently charged flocculants
(Journal of Boron, 2021) Özkan, Şafak Gökhan; Demir, İsmail; Güngören, Can; Baktarhan, Yasin; Yücel, Melike; Çinku, İlgin; Kurşun, İlgin
Mining activities are followed by mineral processing and wet beneficiation methods which generate a significant amount of tailings. Slime fractions are discharged to the tailing ponds with associated process water and this causes storage and disposal difficulties and creates severe environmental problems. Therefore, dewatering these tailings is necessary for both economic and environmental aspects. In this study, the flocculation behaviors of the boron tailings from Agildere and Hisarcik (Turkey) were studied in the presence of anionic, cationic, and non-ionic flocculants. The results showed that the free settling condition was optimum for the Agildere sample. On the contrary, the settling rate of the Hisarcik sample increased considerably by the use of flocculants with a significant decrease in the turbidity of the suspension. Flocculation experiments indicated that the effect of the flocculant type on the flocculation of the Hisarcik sample can be generally ordered as anionic>cationic>non-ionic>no-flocculant. Furthermore, ultrasound was used as a supporting application. The results indicated that although the ultrasound application decreased the settling rate of both samples, lower sediment bed heights were obtained for the Hisarcik sample with ultrasound because of the formation of a more compact sediment bed in the presence of ultrasound.
Effect of conventional and microwave thermal treatments on floatability of low- and high-rank lignites
(Energy Sources Part A-Recovery Utilization and Environmental Effects, 2020) Özkan, Şafak Gökhan; Baktarhan, Yasin; Demir, İsmail; Güngören, Can
Thermal treatment is one of the well-known methods used before froth flotation to remove the polar groups from coal surfaces to make them more hydrophobic. In this study, the effect of conventional and microwave thermal treatments on the wettability of low and high-rank lignite was investigated using flotation experiments, zeta potential, and bubble-particle attachment time measurements, as well as hydrophilicity index analyses. The results showed that both of the thermal treatments increased hydrophobicity, and therefore floatability of the coal samples. The optimum results were achieved with conventional and microwave thermal treatment for the low and high-rank coals, respectively.
Effect of operating parameters on the breakage process of calcite in a stirred media mill
(Mining, Metallurgy & Exploration, 2019) Özkan, Şafak Gökhan; Katıcıoğlu-Bayel, Diler; Toraman, Öner Yusuf
One of the most energy-intensive processes for producing submicron range calcite is stirred media mill. In the present work, numerous operating parameters such as solid mass fraction, grinding media size, media filling ratio, and grinding time have been investigated using a vertical type stirred media mill. The results are evaluated on the basis of mean particle size, specific surface area, and specific energy consumption. After conducting this study, optimum experimental conditions found to be as 70% media filling ratio, 25% solid mass fraction, 1 mm grinding media size, and 120 min grinding time. Besides, energy savings up to 22% were achieved with the choice of proper media size.
Soda/Trona
(İstanbul Maden İhracatçıları Birliği, 2023) Özkan, Şafak Gökhan
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