রাস্তায় গুলি করে কেন খুন, ধন্দই
রাস্তায় গুলি করে কেন খুন, ধন্দই
December 5, 2016, 1:38pm
জেলা
প্রতিদিনের মতোই ঠিক সময়ে বাড়ি থেকে বেরিয়েছিলেন। স্কুটারে চড়ে এগোচ্ছিলেন পোস্ট অফিসের দিকে। মাঝ পথে রাস্তা আগলে দাঁড়াল মোটরবাইকে চড়ে আসা দুই আরোহী। লাথি মেরে স্কুটার ফেলে দিয়ে মাথা লক্ষ করে পরপর দু’টি গুলি। তার পরে দ্রুত বেগে চম্পট দিল ওই আরোহীরা।২০১২ সালের ১৮ এপ্রিল পুলিশ যতক্ষণে পড়িরা মোড়ে ঘটনাস্থলে এসে পৌঁছয়, ততক্ষণে মৃত্যু হয়েছে বারাবনির কেলেজোড়া ডাকঘরের পোস্টমাস্টার সুশীল যাদবের। ঘটনার তদন্ত শুরু হয়। তবে কেন খুন, সে নিয়ে ধন্দ কাটেনি। ঘটনায় জড়িত সন্দেহে দু’জনকে ধরাও হয়। আসানসোল আদালতের চতুর্থ অতিরিক্ত দায়রা বিচারকের এজলাসে মামলাটি বিচারাধীন। ধৃত দুই অভিযুক্ত হরি পাসোয়ান ও অভয় গোস্বামীকে বিচারবিভাগীয় হেফাজতে রেখেই চলছে শুনানি। এই মামলার সরকার পক্ষের আইনজীবী তপন মুখোপাধ্যায় জানান, শুনানি শেষ হয়ে এসেছে।
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Engine vibration can significantly impact the performance and longevity of mechanical systems, particularly for rotating equipment. Understanding the sources and management of engine vibrations is crucial for enhancing operational efficiency and minimizing wear on components. This article delves into the essential aspects of rotor balancing, a fundamental process used to mitigate engine vibrations originating from rotor malfunction.
Engine components such as rotors must maintain symmetry to ensure balanced rotation. When a rotor is perfectly balanced, its mass is evenly distributed around its axis of rotation, resulting in no net centrifugal force acting on any part. However, when imbalance occurs??”often due to issues such as manufacturing defects or misalignment??”unbalanced centrifugal forces generate vibrations as the rotor spins. These vibrations can lead to accelerated wear on bearings, structural deterioration, and even failure if left unaddressed.
Rotors can be classified into two categories: rigid and flexible. Rigid rotors distort minimally under centrifugal forces, and their balancing can often be simplified. In contrast, flexible rotors experience significant deformation, complicating the balancing process due to additional dynamics at play. An imbalance in rigid rotors can be managed effectively through the installation of compensating weights that restore symmetry. This involves identifying the size and positioning needed to counteract the unbalanced forces effectively.
There are two primary types of imbalance: static and dynamic. Static imbalance occurs when a rotor is at rest, where one heavy point causes it to tilt downwards. Dynamic imbalance arises when the rotor is in motion; it involves unequal forces acting in different planes along the rotor??™s length, generating a torque that contributes to vibration. Addressing dynamic imbalance typically requires more sophisticated balancing techniques than static unbalance, as compensating weights must be placed strategically to counteract both the unevenly distributed forces and the resulting torque.
The process of balancing involves measuring engine vibration through various sensors, such as accelerometers and force transducers, which detect either vibration amplitude or force exerted due to imbalances. Data from these measurements inform adjustments to rotor weights, helping to establish an optimal balance. For effective dynamic balancing, a method known as "three starts" is often employed. This method entails measuring vibration with initial weights, introducing test weights, and recording how these affect the vibration before calculating the necessary compensating weights and their placements.
Resonance is another critical factor in engine vibration management. Each mechanical system, determined by its mass and elasticity, has a natural frequency. If the operating frequency of the rotor approaches this natural frequency, the resulting increase in amplitude can cause destructive vibration levels. Therefore, careful design and precise balancing become vital to ensure that operational frequencies are kept safely away from resonance frequencies.
Not all vibrations can be mitigated solely through balancing efforts. Other sources of vibration, such as misalignment of shafts, manufacturing errors, and aerodynamic forces, may contribute to overall vibration levels. It is essential to diagnose and address these factors, as the balancing alone will not rectify other mechanical issues. Thus, a comprehensive approach that combines repair, alignment, and balancing measures is key to resolving vibration problems.
When balancing rotors, it is imperative to adhere to established standards to determine permissible vibration and imbalance levels. Standards such as ISO 1940-1:2007 and ISO 10816-3:2002 provide guidelines for allowable unbalance and vibration limits across various machine classes. Compliance with these standards ensures reliable mechanical performance and minimizes the risk of damage attributed to engine vibration.
In practice, effectively minimizing engine vibration entails not only balancing but also a thorough understanding of the broader mechanical system dynamics involved. Engineers must consider stiffness factors of the equipment support structures, select appropriate balancing techniques, and utilize advanced sensors for accurate vibration assessment. Specialized machines designed for balancing can facilitate this process, utilizing both soft and hard-bearing configurations depending on the nature and requirements of the rotor in question.
In conclusion, effective management of engine vibration is essential for the operational efficiency and longevity of mechanical systems, especially those involving rotors. By understanding the nuances of rotor balancing, the sources of imbalance, and the techniques to mitigate vibration, businesses can significantly enhance their equipment reliability and performance. This multifaceted approach to balancing not only improves immediate operational outcomes but also contributes to the overall maintenance strategy of machine systems, ensuring that engine vibration remains within acceptable parameters for optimal functioning.
Article taken from https://vibromera.eu/