While street vendors have provided goods and services to millions at an affordable rate on their doorsteps since time immemorial, erosion of the rural livelihood base, growing informalisation and ...unabated urbanisation have suddenly increased their numbers in Indian cities in the 1990s. Despite the fact that these workers contribute significantly to the urban economy, they have faced and often continue to experience humiliation, continual harassment, confiscations and sudden evictions. It became imperative to advocate for their rights through the formulation of appropriate policies, the enactment of relevant laws, and the provision of adequate social protection benefits. The National Association of Street Vendors of India (NASVI) played a pivotal and catalytic role in transforming street vendors from non-entities into a formidable force to reckon with. Based on existing published works on the street vendors’ movement in India, a series of key informant interviews and national consultation with stakeholders, the paper aims to document the journey of NASVI in terms of milestones, struggles and successes using the theoretical framework of power resources and capabilities. It also makes an attempt to bring out important lessons for social actors interested in organising informal workers.
Parametric resonance in concrete beam-columns Sharma, Mamta R.; Singh, Arbind K.; Benipal, Gurmail S.
Latin American journal of solids and structures,
11/2014, Letnik:
11, Številka:
6
Journal Article
Recenzirano
Odprti dostop
A dynamic instability, called parametric resonance, is exhibited by undampedelastic beam-columns when under the action of pulsating axial force. The scope of the existing theory of parametric ...resonance is restricted to physically linear beam-columns undergoing finite lateral displacements. In this Paper, the dynamic behaviour of physically nonlinear elastic cracked concrete beam-columns under pulsating axial force and constant lateral force is investigated. The constitutive equations derived earlier by Authors in the form of force-displacement relations are employed here to formulate equations of motion of the SDOF cantilever with mass lumped at its free end. The expected phenomenon of parametric resonance is exhibited in the form of regular subharmonic resonance at about the frequency ratio of two. Resonance peaks broaden with increase in pulsating force. Like damping, physical nonlinearity is also predicted to stabilize the dynamic response at resonance frequencies. In some particular statically unstable conditions, the loss of dynamic stability is shown to occur by divergence. Unexpectedly, similar phenomenon of parametric resonance is exhibited by these physically nonlinear beam-columns undergoing even small lateral displacements. The contribution made to the theory of parametric resonance and the potential relevance of the proposed theory to design of concrete beam-columns is discussed.
An axial follower force acting on the free end of a beam-column is known to remain tangential to its elastica at that point. Elastic beam-columns exhibit infinitely high buckling resistance to static ...compressive follower load. Loss of their dynamic stability is known to occur at critical follower loads, by flutter characterized by vanishing lateral displacement and infinitely high natural frequency. Classical theory deals with physically linear nonconservative beam-columns. Physical nonlinearity exhibited by concrete beam-columns under service loads is caused by the closing and reopening of the extant transverse cracks. In this Paper, analytical expressions for the lateral displacement and lateral stiffness of such concrete beam-columns are derived. Using these expressions, the stability of physically nonlinear elastic flanged concrete beam-columns under the action of a follower compressive axial force and a lateral force is investigated. The significance of the analytical approach and the theoretical predictions is discussed.
Understanding the progressive failure of laminated composite plays an important role in the structural integrity analysis of a structure. Continuum damage mechanics-based approach is one of the ...powerful tools to analyze the failure of laminated composite structures. The present paper investigates the damage evolution and progression in laminated composites with a hole under flexural loading. The presence of high-stress concentrations along with the free edge stresses at the vicinity of the hole in laminated composite leads to complex failure mechanisms. The influence of the change in thickness and lamina configuration on the strength characteristics is presented.
An elastic damage model for concrete has been proposed considering damage-induced bimodularity. A scalar damage parameter has been chosen to quantify the damage. Expressions for the material ...compliance tensor components have been derived from the assumed strain and complementary energy functions stated in terms of the principal stresses and strains. Incremental constitutive equations have been derived incorporating the elastic behavior due to stress increments as well as stiffness degradation. Within the current damage surface, the stiffness of the material with constant damage varies with applied stress variations. During loading beyond the current damage surface, the material experiences stiffness degradation due to increase in extent of damage suffered by it. Using the proposed elastic damage model, the material response has been predicted for different load histories.
Street food vending is fundamental to daily life in many low and middle income countries where much of the urban population rely on food provided by street vendors. While street vendors are known to ...be important providers of food; limited research has investigated vendor’s hygiene practices and their socioeconomic circumstances in India. The aims of this study were to investigate the hygienic practices of food vendors and the context of their socioeconomic and living circumstances. Structured interviews were conducted with 31 street food vendors in Patna, India. The interviews explored issues around vending, hygiene practices, planning, and financial stability. Findings from this study indicate that food vendors are aware of good basic hygiene practices despite having low levels of literacy, low incomes, and limited job security.
•Issues of food safety and hygiene practices in food vendors are unexplored in India.•Food vendors work long hours, experience financial and job insecurity.•Vendors report very low levels of literacy.•Good basic hygiene practices were observed in vendors.
The present study was conducted to record the prevalence of gastrointestinal parasites of pigs by faecal sample examination. Faecal samples were collected in three different seasons viz; monsoon, ...post monsoon and pre monsoon, from in and around Meerut district of Western Uttar Pradesh. A total of 642 faecal samples were collected for a period of one year (2020–21). The overall prevalence rate recorded for gastrointestinal parasites in pigs was 64.4%.The findings of the present work showed that seasons have a significant role on the prevalence of gastrointestinal parasites infection in pigs, with highest prevalence in monsoon (78.34%) followed by pre-monsoon (60.19%) and lowest in post- monsoon seasons (54.67%). Thus, the present study will be helpful in designing the effective control strategy of parasitic infections for optimum production in porcine industry as well as preventive measures against zoonotic diseases spread by pigs.
PDF
